U.S. patent application number 10/079466 was filed with the patent office on 2002-09-19 for process and device for detecting the presence of an object, preferably a leaf sheet-shaped or sheet-shaped object for printing.
Invention is credited to Hunold, Heiko, Metzler, Patrick, Petersen, Ralph.
Application Number | 20020130461 10/079466 |
Document ID | / |
Family ID | 7677862 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020130461 |
Kind Code |
A1 |
Petersen, Ralph ; et
al. |
September 19, 2002 |
Process and device for detecting the presence of an object,
preferably a leaf sheet-shaped or sheet-shaped object for
printing
Abstract
Detecting the presence of an object, preferably a leaf
sheet-shaped or sheet-shaped object on a transport path, especially
for preparation and/or control of a processing of the object,
preferably for printing the object in a printing machine,
especially a digital printer, where the object is transported on
the transport path past a sensor device, preferably a photoelectric
barrier, for detection and registration of the front edge of the
object in the transport direction. After detecting the front edge
of the object and/or its entrance into the measurement area, it is
checked at least once to determine whether the object continues to
be present in the measurement area of the sensor device.
Inventors: |
Petersen, Ralph; (Kiel,
DE) ; Hunold, Heiko; (Wattenbek, DE) ;
Metzler, Patrick; (St. Wendel, DE) |
Correspondence
Address: |
Lawrence P. Kessler
Patent Department
NexPress Solutions LLC
1447 St. Paul Street
Rochester
NY
14653-7103
US
|
Family ID: |
7677862 |
Appl. No.: |
10/079466 |
Filed: |
February 21, 2002 |
Current U.S.
Class: |
271/258.01 ;
271/265.01 |
Current CPC
Class: |
B65H 7/08 20130101; B65H
2511/22 20130101; B65H 2511/514 20130101; B65H 2513/42 20130101;
B65H 2553/41 20130101; B65H 2701/1311 20130101; B65H 2701/1311
20130101; B65H 2511/514 20130101; B65H 2511/22 20130101; B65H
2511/11 20130101; B65H 2513/42 20130101; B65H 2511/11 20130101;
B65H 2220/01 20130101; B65H 2220/01 20130101; B65H 2220/01
20130101; B65H 2220/01 20130101; B65H 2220/03 20130101; B65H
2220/03 20130101; B65H 2511/51 20130101; B65H 2511/51 20130101 |
Class at
Publication: |
271/258.01 ;
271/265.01 |
International
Class: |
B65H 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2001 |
DE |
101 12 946.7 |
Claims
What is claimed is:
1. Process for detecting the presence of an object, preferably a
leaf sheet-shaped or sheet-shaped object on a transport path,
especially for preparation and/or control of a processing of the
object, preferably for printing the object in a printing machine,
especially a digital printer, where the object is transported on
the transport path past a sensor device, preferably a photoelectric
barrier, for detection and registration of the front edge of the
object in the transport direction, characterized in that after
detecting the front edge of the object, it is checked at least once
to determine whether the object continues to be present in the
measurement area of the sensor device.
2. Process according to claim 1, characterized in that the check is
done multiple times in a clock-pulsed manner.
3. Process according to claim 2, characterized in that a certain
time interval pulsing is specified.
4. Process according to claim 2, characterized in that a transport
distance covered by the object is measured and that a certain path
section clock-pulsing is specified for the sensor device.
5. Process according to claim 2, characterized in that the position
of the measurement area of the sensor device is defined and
specified on the transport path with regard to a reference
point.
6. Process according to claim 2, characterized in that for the
check of the presence of the object, a minimum length of an object
in the transport direction is taken into consideration, in such a
way that only upon the presence of the object even after the
minimum length has been covered in the measurement area past the
sensor device, a detected object is recognized as such.
7. Process according to claim 6, characterized in that when using
formatted objects, the length of the smallest format provided for
possible use is considered as a minimum length.
8. Process according to claim 2, characterized in that the clock
pulsing, when using a time interval clock pulsing taking into
account the transport speed, is used for a measurement of the
length of the object.
9. Device for detecting the presence of an object, preferably a
leaf sheet-shaped or sheet-shaped object on a transport path,
especially for preparation and/or control of a processing of the
object, preferably for printing the object in a printing machine,
especially a digital printer, where the transport path passes by a
sensor device, preferably a photoelectric barrier, for detection
and registration of the front edge of the object in the transport
direction, characterized in that the sensor device (4) is set up to
check at least once to determine whether the object (3) continues
to be present in the measurement area (5) after first detecting the
object (3).
10. Device according to claim 9, characterized in that the sensor
device (4) is clock-pulsed for multiple checking.
11. Device according to claim 10, characterized in that a certain
time interval clock-pulsing is specified for the sensor device
(4).
12. Device according to claim 10, characterized by a measurement
device (10) for measuring a transport path that is covered by the
object (3) is in connection with the sensor device (4) to specify a
certain path section clock-pulsing for the sensor device (4).
13. Device according to claim 12, characterized in that the sensor
device (4) and the measurement device (10) are connected to each
other to measure the transport distance via a computational unit
and/or a signal output unit (6).
14. Device according to claim 9, characterized in that the position
of the measurement area (5) of the sensor device (4) on the
transport path is defined and specified with regard to a reference
point (9).
15. Device according to claim 9, characterized in that to transport
the object (3) along the transport path, a transparent conveyor
belt (1) is provided, on which the object (3) can be placed.
Description
FIELD OF THE INVENTION
[0001] The invention involves a process and device for detecting
the presence of an object, preferably a leaf sheet-shaped or
sheet-shaped object on a transport path, especially for preparation
and/or control of a processing of the object, preferably for
printing the object in a printing machine, especially a digital
printer, where the object is transported on the transport path past
a sensor device, preferably a photoelectric barrier, for detection
and registration of the front edge of the object in the transport
direction.
BACKGROUND OF THE INVENTION
[0002] In the operation of a digital printer, in particular, during
the operation of an electrophotographic printer, the imaging
operation for printing must be prepared for each sheet to be
printed, because a permanent printing block or mold is not used
(non-impact printing). That is, the printed image must be recreated
for each sheet to be printed, even if the printed image does not
change from sheet to sheet. This imaging requires time so that the
arrival of a new sheet must be announced at the proper time, so
that time is available for the imaging and is planned for by the
printer. The announcement of a next sheet is done by a sensor
device which detects the presence and/or the arrival of an object
on the transport path in its measurement area. This object can be
the arriving sheet itself, which is detected by the sensor device
as soon as its front edge enters the measurement area of the sensor
device, but the object can also be a mark or the like, for example,
which runs along with the conveyor belt and its presence is
likewise detected by the sensor device as soon as the front edge
enters the measurement area. In this process, primarily a one-way
photoelectric barrier or a two-way photoelectric barrier, or a
reflection photoelectric barrier, come into consideration as the
sensor device.
[0003] One problem, however, can be that the sensor device should
detect the entrance into its measurement area in as precise a
manner as possible so that the measurement area of the sensor
device, for example, through a narrow slit, is set to be as small
as possible in order to, in this way, select the measurement
inaccuracy that results from the extension of the measurement area
itself, to be as small as possible. A precise sensor device of this
type is namely also subject to slight interference effects by
phenomena in the measurement area, which mediate the appearance of
an existing object. For example, slightly extended, local damages,
such as scratches or soiling, can also readily trigger the sensor
device and in this way lead to erroneous triggerings or erroneous
switchings of the imaging device of an electrophotographic
printer.
SUMMARY OF THE INVENTION
[0004] The purpose of the invention is thus to improve a process
and/or a sensor device to the effect that in spite of high
precision, the danger of erroneous detection is reduced. This
purpose is achieved in regard to the process in that after
detecting the front edge of the object and/or its entrance into the
measurement area, it is checked at least once to determine whether
the object continues to be present in the measurement area of the
sensor device. By this measure according to the invention, it can
be reliably ensured that a more expansive object has actually
entered into the measurement area of the sensor device and not a
local position of interference that only gives the impression of an
object.
[0005] According to another embodiment of the process according to
the invention, the check is done multiply at defined intervals that
can be relatively small, in that the sensor device operates by
clock pulses. In this way, the entrance and exit of the object can
be detected precisely and it can be recognized that in this entire
detected area, only an extended object is present. In the process,
the clock pulsing according to the invention can be time-referenced
or path-referenced, whereby a timed frequent clock pulsing is
allocated to corresponding path distances via another path
measurement and can be converted into these path distances.
However, different results and advantages result for the different
clock pulsings. A timed clock pulsing can be implemented directly
for the sensor device and is sufficient if the sensor device itself
should make the decision about the presence of an object. If the
clock pulsing is performed in a manner referenced to the path
distance, the clock pulsing is only as uniform in time as the
movement of the transport device used. However, this has the
advantage for the direct preparation control, e.g. of an
electrophotographic printer, that transport speed fluctuations no
longer falsify the measurement result.
[0006] If the sensor device is clock-pulsed in a manner referenced
to the path-distance or a time clock is otherwise set in relation
to a path distance measurement, then a statement about the
distance, for example, between the position of the sensor device
and the print gap of the imaging device, can be made. This is
especially true if, as provided according to a further embodiment,
the position of the measurement area of the sensor device is
defined and specified on the transport path with regard to a
reference point. Also, as likewise preferably provided, the length
of the object can be measured.
[0007] For the check of the presence of an object in the
measurement area of the sensor device and to eliminate
interference, a minimum length of an object to be expected is
preferably provided, which is checked. For formatted objects, the
shortest format length that should ever be used is taken into
account for this purpose, whereby the prescribed minimum length is
selected to be this short or for the purposes of safety, shorter.
Each object that is shorter than the minimum length is considered
to be a source of interference.
[0008] A device according to the invention is characterized in an
independent solution of the inventive purpose, in that the sensor
device is set up to check at least once whether the object is still
present in its measurement area after the detection of the object.
In particular, the device according to the invention for multiple
checking for the presence of an object can be operated in a clock
pulsed manner, namely clock pulsed in a time-referenced or
path-distance-referenced manner. For a time-path relation,
preferably the sensor device and a measurement device are connected
together for measurement of a transport distance via a
computational unit and/or a signal output unit. The position of the
measurement area of the sensor device on the transport path of the
objects is preferably defined and specified with regard to a
reference point. For the transport of objects along the transport
path, preferably a transparent conveyor belt is chosen, on which
the objects can be placed and that itself does not interfere with
an optically operating sensor device, unless it were to be soiled
or scratched, for example, or otherwise damaged.
[0009] The invention, and its objects and advantages, will become
more apparent in the detailed description of the preferred
embodiment presented below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Embodiment examples of a device according to the invention,
from which other characteristics of the invention can also be
gathered, but to which the invention is not limited in its scope,
are shown schematically in the following drawings:
[0011] FIG. 1 which schematically shows a section of a paper
transport path of a printer with a first embodiment form of a
device according to the invention, depicted in the manner of a
block diagram, in a side view, and
[0012] FIG. 2 which schematically shows a second embodiment form
according to FIG. 1, with an additional path measurement
device.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 shows schematically in a side view and partially in
the manner of a block diagram, a section of a transport path for
the paper sheet to be printed by an electrophotographically
operating printer having a sensor device for detecting a paper
sheet on the transport path.
[0014] A transparent conveyor belt 1 is indicated, which runs along
the transport path in the transport direction 2. On the conveyor
belt 1, a paper sheet 3 is shown. Above the conveyor belt 1, a
sensor device is located to detect a paper sheet 3 on the conveyor
belt 1. The sensor device includes a photoelectric barrier 4 in
particular, which registers the entrance and/or the presence of a
paper sheet 3 in its measurement area and/or measurement point 5.
The photoelectric barrier 4 is connected via a computational unit
and output unit 6 with a time output device 7.
[0015] As soon as traveling the front edge of the paper sheet 3
traveling reaches the measurement point 5 of the photoelectric
barrier 4 and enters into it, this is registered by the
photoelectric barrier 4. This occurs because the photoelectric
barrier 4, as a two-way photoelectric barrier whose light passes
through the transparent conveyor belt 1 unobstructed, is suddenly
interrupted, or because it registers, as a reflection light
barrier, light reflected by the paper sheet 3. The presence of the
paper sheet 3 in the area of the measurement point 5 is checked
many times during its transport in a clock-pulsed manner with a
clock-pulse from the time output device 7. After each repetition
that has yielded the result that the paper sheet can still be
detected at the measurement point 5, a counter of the computational
and output unit 6 is incremented, so that the counting rate
multiplied by the time interval of the clock pulses produces a
measuring time period. This measuring time period corresponds,
taking into account the transport speed of the paper sheet 3 in the
transport direction 2, to a measuring distance 8 that the front
edge of the paper sheet 3 passes through over the measuring time
period, starting with the measuring point 5. This measuring
distance 8 can have a defined minimum length, in order to ensure
that a more expansive paper sheet 3 had actually been detected and
that an interference or damage through a locally limited soiling or
a scratch of the conveyor belt 1 is not present. For example, the
measuring distance 8 can be selected to be somewhat shorter than
the shortest expected paper sheet length of the paper sheet formats
provided for use.
[0016] Because of the paper sheet 3 definitely recognized at the
measuring point 5, the printer (not shown in greater detail) can be
prepared for the arrival of the paper sheet in the print gap. The
printing process, especially the imaging, can then be adjusted
exactly in time to the arrival of the paper sheet. For this
purpose, the position and/or the distance of the measuring point
must be known as precisely as possible. This position is thus
defined relative to a reference point 9. For the time preparation
and adjustment of the printer, however, in addition to the position
and/or distance of the measurement point 5 from the print gap, the
measuring distance 8 must be taken into account. This is because
only after this measuring distance 8 has passed, the paper sheet 3
is definitely recognized and is announced, so that this path
distance up to arrival at the print gap is no longer available, and
must be considered as a delay of the reporting of the paper sheet
3.
[0017] In FIG. 2, a second embodiment example of a device according
to the invention is shown in a diagram corresponding to FIG. 1. The
same structural elements are shown with the same reference
indicators as shown in FIG. 1. In the embodiment example according
to FIG. 2, only the time output device 7 of FIG. 1 has been
replaced by a path measurement device 10, so that the clock pulsing
and/or inquiry repetition through the photoelectric barrier 4 can
occur in a manner having equal path sections. Also here, the
measurement distance 8 is considered to be an already covered
distance during the announcement of the paper sheet 3.
[0018] In both cases of FIG. 1 and 2, the photoelectric barrier 4
can be set so precisely and sharply defined that the measurement
area and/or measuring point 5 is extended only a few micrometers.
Interference by local foreign bodies or damage of the conveyor belt
and resultant erroneous triggerings of the printer are prevented by
the verifications over the measuring distance 8.
[0019] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *