Hardware manual

US 7,915,570 B2
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SMART CAMERA WITH AN INTEGRATED
LIGHTING CONTROLLER
PRIORITY CLAIM
This application claims priority to provisional patent appli
cation No. 60/ 953 ,889 titled “New Architecture for Industrial
Camera Lighting Circuit with High Power Density and Long
Strobe Intervals,” to Cetrulo et al., ?led on Aug. 3, 2007.
FIELD OF THE INVENTION
The present invention relates to the ?eld of machine vision,
and more particularly to a smart camera with an integrated
lighting current controller.
DESCRIPTION OF THE RELATED ART
In many applications, machine vision or image processing
analysis is used to inspect or locate an object. For example, in
manufacturing applications, machine vision analysis may be
used to detect defects in a manufactured object by acquiring
images of the object and using various types of image pro
cessing algorithms to analyze the images. As an example, a
system to manufacture electrical components such as capaci
tors may use machine vision to examine respective sides of
the capacitors in order to detect manufacturing defects,
ensure that the capacitors are labeled, marked, or color coded
properly, etc.
Machine vision applications may use image processing
software operable to perform any of various types of image
analysis or image processing functions or algorithms in
examining an acquired image of an object. Any type of cam
era or other device may be used to acquire the images to be
analyzed in a machine vision application, including digital
cameras, line scan cameras, infrared imaging devices, x-ray
imaging devices, ultra-sonic imaging devices, and any other
type of device which operates to receive, generate, process, or
acquire an image or sensor data.
Typically, the image processing and analysis of image data
is performed by a computing system which may be coupled to
the camera. Increasingly, however, such image processing
capabilities are performed by the camera or sensor by hard
ware and/ or software “on-boar ” the device. The term “smart
camera” is intended to include any of various types of devices
that include a camera or other image sensor and a functional
unit (i.e., a processor/memory and/or programmable hard
ware, such as a ?eld programmable gate array (FPGA))
capable of being con?gured to perform an image processing
function to analyze or process an acquired image. Examples
of smart cameras include: NAVSYS Corporation’s GI-EYE,
which generates digital image data that are automatically
tagged with geo-registration meta-data to indicate the precise
position and attitude of the camera when the image was taken;
Vision Components’ GmbH Smart Machine Vision Cameras,
which integrate a high-resolution Charge Coupled Device
(CCD) sensor with a fast image-processing signal processor,
and provide various interfaces to allow communication with
the outside world; and Visual Inspection Systems’ SMART
cameras with on-board DSP capabilities, including frame
grabbers and robot guidance systems, among others.
Lighting controllers may be used to power lightheads (light
sources) that provide illumination of objects to be imaged.
Lighting controllers can use either voltage or current to con
trol and power light sources. Lighting current controllers can
provide either continuous or strobed current at variable cur
rent levels as required for the application, determined by
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factors such as ambient light conditions and required expo
sure time. Existing lighting current controllers generally use
linear power supply designs which are bulky, heavy, and hot.
Various existing approaches to use light sources with a cam
era in machine vision/ image processing applications are
described below. Examples of lighting controllers include
BANNER PRESENCE and SCM products, ETS
LINDGREN MODULAR LIGHTING CONTROLLER,
ADVANCED ILLUMINATION SIGNATECH S4000/6000
and PULSAR products, SIEMENS PP610 product, and
GARDASOFT PP420 product, among others.
A ?rst approach may use an external lighting current con
troller along with an external power supply. This approach
works well but requires additional and external components,
e. g., an external lighting current controller, and sometimes an
additional power supply. Furthermore, if the lighting current
controller and/ or the power supply use regular linear power,
then the power draw and/or heat dissipation may become an
issue and may need bigger power supplies and/ or heat dissi
pation devices. Some heat dissipation devices, such as fans,
may be undesirable due to added complexity and cost, as well
as additional reliability issues.
Another approach may utilize integrated lights, such as
LED’s or other light sources, built into a smart camera. How
ever, the integrated lights on a smart camera (e.g., integrated
illumination) do not provide the quality and intensity and
variety of con?gurations needed for many machine vision
applications. Systems with integrated lights do not have the
ability to directly control and/ or power external light sources.
As a result, if the user’s illumination requirements can not be
met by the limited selection of integrated lights provided by
the manufacturer, this approach does not solve the user’s
application.
Furthermore, the built-in lighting solutions mainly use a
voltage signal to control and power the built-in LED(s). The
brightness of an LED is usually controlled by the amount of
current through the LED. Using an unregulated or regulated
voltage signal that is, by some mechanism, converted to cur
rent is not accurate, and precludes the possibility of overdriv
ing the LED(s) in a strobing application.
SUMMARY OF THE INVENTION
Various embodiments of a smart camera system with an
integrated lighting current controller are presented below. In
some embodiments, the smart camera may comprise a pro
ces sing unit, imager, memory, and an integrated (i.e., built-in)
lighting current controller. The smart camera may include a
housing containing all the elements of the smart camera. The
smart camera may also use a built-in imager for image acqui
sition, or alternatively it may connect to an external imager/
lens/ camera for analog or digital image acquisition.
The integrated lighting current controller may be operable
to couple to one or more external light sources, which may be
regular of-the-shelf lighting sources such as LED’s or other
lights. The lighting current controller may be able to strobe
the lights substantially aron the time of the exposure, and
possibly right before the exposure, such that the unit under
test has the desired lighting when the exposure is taken.
The lighting current controller uses a switching power
supply that minimizes power dissipation, and because of its
limited power dissipation, it can be integrated into the smart
camera. The lighting current controller can control and power
the light source by generating a current pulse from the switch
ing power supply (while in the active state). The switching
power supply may receive a pulse-width-modulated (PWM)
signal that controls it output, and the PWM signal itself may