Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2001-02-09
2004-06-15
Bruce, David V. (Department: 2882)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559440, C356S238100
Reexamination Certificate
active
06750466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to web inspection systems and more specifically to smart camera systems for detecting flaws and defects of web material.
2. Background
A “web” is a flat material produced continuously in large quantities and at very high rates. Typical web materiel includes fabrics, sheet metal, paper, and non-woven plastic, etc. Inspection of the web material surface is required during production to find flaws and defects. Failure to detect these flaws and defects may result in thousands of feet of unusable web material. Thus, there exists varying methods of web inspection from manual inspection and sampling to image acquisition, processing and analysis.
FIG. 1
illustrates a traditional system
10
for web inspection utilizing line scan cameras
22
positioned above a web
12
. Typically, two types of sensor technology, charge coupled device (CCD) or CMOS, are utilized. While CMOS technology allows the signal processing electronics to be on the same chip as the sensor, CCD sensor technology offers advantages superior imaging quality as compared to CMOS sensors, and stand alone components. Continuing with
FIG. 1
, high bandwidth camera-specific data cables
34
are required to transfer data from the line scan cameras
22
to a vision processor
32
. A typical high bandwidth data stream transfer is forty (40) million pixels per seconds, i.e., 500 Mbits per second for pixels of eight (8) bits.
The megapixel data stream is transferred over the camera-specific cables
34
to frame grabber modules
24
in the vision processor
32
. Frame grabber modules
24
utilize standard integrated circuit (IC) boards to digitize an analog video stream image from a line scan camera
22
. The digitized images, represented by arrays of numbers, are streamed to pipeline vision processors
26
for real time preprocessing. The pipeline vision processors
26
utilize dedicated image processing boards for data and image analysis that may be different for various webs. For example, a pipeline vision processor
26
may be configured to extract specific information from an image. The processed images from each of the pipeline vision processors
26
are sent to an image analyzer processor
28
that further analyzes and processes an image of the full width of the web
12
. The web inspection system
10
of the prior art may further include an image buffer board
30
for data storage. The vision processor
32
of the prior art requires a large chassis to house the IC boards of the frame grabber modules
24
, the pipeline vision processors
26
the image analyzer processor, and the image buffer
30
.
The processed image from the vision processor
26
is sent to a host computer
14
for display on the graphical user interface (GUI) of the host computer
14
. Also connected to the host computer
14
, is a defect marker
18
and an encoder
16
. The encoder
16
sends information to the host computer
14
including the speed of the web
12
. The web
12
typically moves over a rotary device driven by a shaft and roller that produce pulses per unit distance. The host computer
14
utilizes this information to determine the size and position of a defect. The host computer
14
may also include a database input/output board to control a defect marking system
18
, and other peripheral device connections
20
.
The web inspection systems
10
of the prior art present several disadvantages. As described above, prior art web inspection systems
10
require a high number of components that are supplied by many different manufacturers, thus presenting compatibility problems. Integration of the components is difficult and expensive, and the resulting system is often difficult to configure and use. The prior art web inspection systems
10
typically have large footprints and require racks or large custom boxes of boards for parallel processing. These extra racks of equipment and the operator console, or host computer
14
, must be out on the floor and relatively close to the web equipment
12
due to the constraints on the length of connecting cables which must transmit a large bandwidth of data. For example, custom shielded cables are required to connect components to protect the video signal from picking up background noise. The requirement of proprietary cables and the large bandwidth transmission of the high speed raw image data from the cameras limits and/or preempts the use of standard factory ethernet cables to link all components and factory computers.
A further disadvantage of the prior art web inspection systems
10
as shown in
FIG. 1
is the low mean time between failure due to the number of components. In addition, a web inspection system
10
, as shown in
FIG. 1
, is an unbalanced architecture, meaning that one component in the system often limits the performance of the system. For example, high speed data sent over cables
34
may jam processing in the vision processing box
32
. Also, high defect rates may cause overload occurrences in the image analyzer processor
28
. Expansion of an unbalance architecture to add more capability is usually very expensive, and the system
10
is often already maximized, e.g. the rack holding the equipment cannot accept more boards. Another drawback of the non-robust web inspection system
10
of the prior art is that the system
10
is not easily scalable. Therefore, if a customer requires the detection of defects that are half the size that the current system
10
is capable of detecting, more cameras may be added, but the system
10
cannot be configured to accept more pipeline vision processors
26
and/or a second image analyzer
28
.
Thus there exists a need for a balanced and robust web inspection system that is easily integrated with an existing manufacturing Ethernet, and is capable of detecting a high rate of web flaws and defects.
SUMMARY OF THE INVENTION
It is an advantage of the present invention to provide smart cameras for processing images at the front end of the system to limit the bandwidth required to transmit image data.
It is a further advantage of the present invention to provide a robust web inspection system that is capable of expansion.
It is another advantage of the present invention to provide a web inspection system that may be connected to an existing factory ethernet.
It is yet another advantage of the present invention to provide a web inspection system that can be readily expanded as required.
It is yet another advantage to provide a low contrast web inspection system that is capable of detecting flaws and defects in web material that are close to the noise level.
Still another advantage of the present invention is to provide a web inspection system that requires a limited number of components thus increasing the mean time between failure of the web inspection system.
The present invention also provides a balanced architecture for processing data that results in predictable response and more robust behavior.
In an exemplary embodiment of the present invention, a web inspection system includes at least one smart camera for generating digitized images of portions of a web material having a flaw or defect. Each smart camera is connected via an ethernet hub to a host computer. The host computer and a web encoder monitor the web speed and send control signals to the each smart camera. Each smart camera is connected to a marking system for marking the web proximate to each flaw or defect with corresponding codes or other markings. In an exemplary embodiment each smart camera includes a head board for capturing an image of a portion of a web, and digitizing the image, a processor for analyzing the image, an input/output board for controlling the input and output of the image data signals, and a power supply board for supplying the smart camera components with required voltages.
In an exemplary embodiment of the present invention, the smart camera is capable of detecting very small flaws and defects of the web, i.e. the contrast between a flaw and good web material is clos
Becker Robin D.
Guha Sujoy D.
Kiraly Chris M.
Bruce David V.
Gordon & Rees LLP
Song Hoon
Wintriss Engineering Corporation
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