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FIELD OF THE INVENTION
[0001]The present invention relates to the visualization systems using high
intensity arc lamps and more particularly a ventilation and cooling device for the
arc lamp and electronic circuitry of a light source unit of the visualization
systems.
BACKGROUND OF THE INVENTION
[0002]Cool and white light is used in various applications such as in signs,
displays, general area lighting and also with specialized applications like Medical,
Scientific etc. In the medical and specifically surgical applications, a light source
unit is used to provide cool and white light for various medical applications such
as visualization of the body structures, curing of composite materials etc. The
light source unit is used to provide the illumination light for the structures inside
the body cavity through a light guide. A fiber optic cable is usually used as the
light guide along with these units. A typical cable consists of a receptor end
illuminated by a light source, the opposite end being adapted to receive a light
emitter. Light travels from the light source through the fiber optic cable and is
emitted by the light emitter. Such devices typically utilize a high intensity Xenon,
halogen or other lamps as a light source.
[0003]The light source unit usually consists of several modules such as a lamp, a
lamp holder in which the lamp is fitted, a heat sink, a fan, a power source and an
outer housing in which all these modules are installed. One such fiber optic
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illumination system described in the US Pat. No. 5653519 provides a cooling
system for these high intensity arc lamps. Some equipment such as the medical
visualization system, LCD projector, DLP projector and like need an electrical
power source as well electronic circuitry along with the light source.
Conventionally to provide a proper cooling arrangement for the Light Source and
Electronic components two separate enclosures are provided.
[0004] To provide cool and white light, high intensity light bulbs are commonly
used. These high intensity light bulbs also known as arc lamps create a large
amount of heat while providing the light beam. As the medical visualization
system are becoming very compact and portable various modules are integrated
in a single enclosure. Modules such as the light source, electronic circuitry for
image processing and an electrical system as a power source could be fitted in a
single enclosure. Due to this kind of integration various heat-dissipating modules
are arranged in close proximity with each other. As the heat generated within
the enclosure is increased and the area to circulate the cooling medium is
restricted, there is a need to have an appropriate ventilation and cooling
arrangement for a compact visualization system whereby it provides a good &
efficient cooling of the light source as well as the electronic components for
better performance and life.
[0005]The light sources generate a significant amount of heat. As the
temperature of the device rises, the receptor end of the fiber optic cable will
frequently be damaged or destroyed. Using a heat sink and the air blown by a
fan on the heated light source dissipates heat produced by the high intensity
light sources. Conventionally different types heat sinks are being used to
dissipate the heat produced by the light sources. The heat sinks used for these
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applications are heavy and elaborate so that the weight of the Light source unit
is considerably increased which hampers the portability of the unit. Also due to
elaborate design of the heat sink onsite replacement of the bulb to provide an
uninterrupted application of the light source unit, is severly hindered.
[0006]Medical applications of the Light sources as described earlier require high
amount of reliability and safety. The operating temperature of the lamp itself is
high, the lamp tends to expand against its heat sink which raises a danger of
breakage of fragile components. Also due to comparatively short life expectancy
of the high intensity light bulbs and a possibility of blowing out of these sources
during the operations, back up of the supplies is essential. Therefore, a large
inventory of equipment according to prior art is essential, more so, because
replacement of lamps in the prior rat light units requires return of the equipment
to a factory or distributor setting where a new lamp can be installed and
adjusted for proper alignment. To maximize the life and quality of light high
intensity, appropriate cooling of the light sources is necessary even after the bulb
has been switched off.
[0007]Therefore there is a need to have a ventilation and cooling arrangement
to effectively cool the heated light source including the electrical components
fitted in a single compact unit, to allow onsite replacement of the bulb with
proper alignment and to protect the receptor end of the fiber optic cable.
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OBJECTS OF THE INVENTION
[0008]It is therefore an object of the invention to propose a ventilation and
cooling device in an imaging system, which provides an improved cooling effect
to the light source and the electronic circuitry of the system.
[0009]Another object of the invention is to propose a ventilation and cooling
device in an imaging system, which reduces the frequency of damage and
obsolescence of the receptor end of the fibre optic cable of the system.
[0010]A still another object of the invention is to propose a ventilation and
cooling device in an imaging system, which employ light and compact heat sink
which allows portability of the device including in-situ replacement of the light
source when replaceable.
[0011]A further object of the invention is to propose a ventilation and cooling
device in an imaging system, which is simple and cost-effective.
SUMMARY OF THE INVENTION
[0012]Accordingly there is provided a method and a system for cooling a high-
intensity light source including an electronic circuitry in compact visualization
systems. The system comprises several modules interposed in a housing such
that the lamp and the other electronic components are enabled to operate at
optimum temperature for effective functioning of the components and for getting
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desired output. The several modules including the active units are maintained in
the internal environment within acceptable temperature limits. In critical
instruments having application in the medical environment, where the quality
and age of the light source is dependent on the ambient temperature it is very
important to effectively control the inside temperature. For efficient functioning
of these lights an effective ventilation and cooling device is provided. Appropriate
arrangement and positioning of the active units (Fan) including the passive units
(baffle) are very critical to achieve an efficient cooling result. Along with this new
configured device, properly designed and configured heat sink, the high intensity
light source and the electronic subassembly create air blocks for facilitating the
heat dissipation by convection.
[0013] Placement of the heat generating components such as a light source and
an electronic subassembly in a single housing is accompanied by a timer circuit
for controlling the active components of the cooling assembly for enhancing and
optimizing the performance and life of the light source and the electronic
subassembly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 is a schematic representation of a medical visualization system with
arrangement of the of the components inside the light source unit
FIG. 2 is an exploded view of a light source unit with illustration of a ventilation
and cooling device.
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FIG. 3 is an illustration of a fan assembly of the light source unit according to the
invention.
FIG. 4 is an exploded view of a heat sink assembly and an illumination control
means of the light source unit of the invention.
FIG. 5 is an illustration of the heat sink assembly with the light source
subassembly and the illumination control means of the light source unit of the
invention
FIG. 6 is an illustration of the airflow vents and supporting member of the
ventilation and cooling device of the invention.
FIG. 7 is a top view of the light source unit without the top cover illustrating the
airflow in the light source unit
FIG. 8 is a schematic representation of a timer circuit for controlling the active
components of the ventilation and cooling device of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] For purposes of explanation, the figures and the description are provided
with respect to an example of a cooling arrangement of a medical visualization
system but it will be understood the invention can have applicability other areas.
In particular, but without limitation, the present invention can have applicability
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to systems and methods used for cooling the high heat generating components
and also where several heat-generating components are fitted in closed
proximity with each other. Specifically some examples of such application would
be in general purpose lightening, projector units, fiber optic lighting system,
medical applications, and compact electronic equipment.
[0015] FIG. 1 is a schematic representation of a medical imaging system 100
wherein the application of an embodiment of the present invention is illustrated.
The imaging system 100 typically includes a light source unit 200, a display and
recording module 120, a video connector 126, a camera unit 150, a camera
connector 180, a fiber optic cable 170 and an endoscope 190. The light source
unit 200 includes a housing 110, a heat sink assembly 500, a light source
subassembly 520, a cooling module 300, a power supply module 240, an
electronic subassembly 800, and an indicator module 214, a fiber optic
receptacle 560, and an illumination control maens 570.
[0016] The light source subassembly 520 includes a light source 524, a reflector
522, and a bulb holder 526. The light source 524 and the reflector 522 are
attached to the bulb holder 526. The heat sink assembly 500 is coupled to the
light source subassembly 520. The heat sink assembly 500 is provided to
dissipate the heat generated by the light source assembly 520. The heat sink
assembly 500 is also attached to the fiber optic receptacle 560. The fiber optic
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receptacle acts as an optic port and provides a slot to align the receptor end of
the fiber optic cable 170 with the beam of light generated by the light source
subassembly 520. The light source unit 200 is powered by the power supply 240.
The power supply 240 has two major supply modules, a low voltage module 242
and a high voltage module 244. The low voltage module 242 is mainly made up
of at least one transformer and the high voltage module 244 is mainly made up
of ballast. The high voltage module 242 provides power supply to the light
source subassembly 520 and the cooling module 300. The low voltage module
provides power supply to the electronic subassembly 800 and the camera unit
150. The electronic subassembly 800 includes a timer circuit 810 and a video
isolation circuit 850. The timer circuit 810 is attached to the indicator module
214. The cooling module 300 is placed within the housing 110 such that a fan
assembly 310 blows cool air on the heat sink assembly 500, the light source
subassembly 520 and an illumination control means 570. The cooling module
300 draws the cooling air such that air is sucked from the areas surrounding the
power supply module 240 and the electronic subassembly 800.
[0017] The imaging system 100 functionally comprises of two essential flows.
The first being the flow of light for illuminating from the light source 524 to the
site to be visualized. The second being the flow of the video signals from the
examination site to the display 120. The following paragraphs explain these flows
and associated system modules.
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[0018]The light originating from the light source 524 is transformed into a
focused beam of light by the reflector 522. The focused beam of light passes
through the illumination control means 570, which is located between the light
source 524 and the fiber optic receptacle 560. The illumination control means
570 controls the intensity of the light beam that passes through the fiber optic
receptacle 560. The light beam is thereafter, transmitted through the fiber optic
cable 170 to the endoscope 190. The light beam passes through the endoscope
190, and illuminates the site to be visualized.
[0019]Once the site is illuminated, the object reflects the light and the reflected
light passes through the objective lens of the endoscope 190 and further
transmitted to the camera unit 150. The camera unit 150 converts the reflected
light to video signal by an image-processing unit attached to the camera unit.
Thereafter, the video signal is passed to the electronic subassembly 800 through
the camera connector 180. The camera connector 180 is attached to the video
isolation circuit 850 by a limo connector 880. The video signals are modulated
and isolated by the video isolation circuit 850. The video isolation circuit 850 also
includes video output ports 890. The output ports 890 provide the video signal to
the display and recording module 120 through the video connector 126. The
display and recording module 120 is used to view and/or record the video images
from the visualized object.
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[0020] Fig 2 is an exploded view of the light source unit 200 with illustration of
the cooling arrangement. The housing 110 is a four-piece assembly and
comprises a front panel 210, a top cover 220, a bottom plate 230, and a middle
panel 600. The front panel 210 is fitted on the bottom plate 230 with a
supporting plate 218. The supporting plate 218 is also attached to the middle
panel 600 at the attachment member 616. The supporting plate 218 is attached
via a fastening member to the bottom 230 including to the middle panel 600.
The top cover 220 is fitted on the middle panel 600 and tightened by the knurl
screws 222. The attachment of the top cover 220 with the middle panel 600 by
knurl screws 222 makes the operation tooless. The housing 110 can be made of
metal, alloy, carbon fiber, heat resistant plastic, glass, composites, ceramic, and
the like. The housing provides protection to the inside components. The housing
110 also helps in dissipating the heat produced by the components inside the
housing 110 and in reducing the EMI / EMC effect on the electronic subassembly
800 and power supply module 240 from electromagnetic interference caused by
other electronic & electrical equipments in the surrounding environment of the
light source unit 200 during the functioning of the unit 200.
[0021]The front panel 210 acts as an attachment arrangement for various
components such as the indicator 214 and the indicator PCB 215, the front panel
on/off switch 216 and the lemo connector 880. The front panel 210 comprises
an opening 212 for fitting the fiber optic receptacle 560. The front panel 210
further comprises a window 213 for accommodating a intensity control knob 580.
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An EMI filter 660 is mounted on rear of the middle panel 600. The EMI filter 660
is electrically connected to the Mains On/off Switch. This EMI filter 660 is used to
suppress common mode noises and differential mode noises. Generally, these
filters 660 eliminate electromagnetic interferences created by the equipment and
the component itself. A safety micro-switch 670 is also installed in a frame
mounted on the middle panel 600. This switch 670 is used to shut off the power
supply to the light source 524 when the top cover 220 is removed.
[0022]The bottom plate 230 is used for fitting various modules of the light
source unit 200. The electronic subassembly 800 and the power supply module
240 are arranged in a stacked configuration on same side of the cooling module
300. The high voltage module 244 comprises mainly a ballast therefore it is
heavy and generates a high amount of heat. Therefore the high voltage module
244 is placed in the bottom of the stacked arrangement. The high voltage
module 244 is covered with a ballast casing 250. Functionally the ballast casing
250 provides an EMI/EMC shield, a protective covering and dissipates the heat
produced by the high voltage module 244. The low voltage module 242 and the
electronic subassembly 800 is placed above the high voltage module 244 such
that they are fitted on top of the ballast casing 250. The PCB chassis 252 covers
the electronic subassembly 800 and it is fitted on the top of the ballast casinq
250. Functionally the PCB chassis 252 provides an EMI/EMC shield, and a
protective covering and dissipates the heat produced by the electronic
subassembly 800. The Ballast casing 250 and the PCB chassis 252 has numerous
openings 254. The openings 254 are created to facilitate the flow of air over the
electronic subassembly 800 and the power supply module 240. Also the openings
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254 reduce the overall weight of the light source unit 200. The openings 254 are
illustrated in the fig 4. The embodiment of the present invention illustrates the
openings 254 in the circular and rectangular configuration, however, numerous
shapes other and their variations may occur to those skilled in the art, such as,
triangular, polygonal, square and the like.
[0023] Fig 3 is an illustration of the cooling module 300. The cooling module
comprises of a fan assembly 310, a dampner 320 and a bracket 330. The fan
assembly 310 has a chassis 312 and a fan body 314 with rotating blades. The
bracket 330 has a one front supporting plate 336, two supporting side plates
338, and two base plates 332. The base plate 332 has slots 334 for fastening
member for fitting the fan bracket on the bottom plate 230. The body 314 is
fixed on the chassis 312. The dampner 320 is made up of shock absorbing
material and is fixed in between the fan assembly 310 and the bracket 320.
Fastening member fits the fan assembly 310 on the bracket 330 with the
dampner 320 in between. The dampner 320 is used to reduce the vibration of
the fan assembly 310. The dampner 320 can be made of shock absorbing
material made of foam, wool, carbon fiber, rubber, paper, plastic, silicone and
the like. The cooling module is one of the essential components of the cooling
arrangement and it provides ventilation of air inside the housing 110.
[0024] Fig 4 in conjunction with the fig 5 illustrates the heat sink assembly 500.
The heat sink assembly 500 is described along with the light source subassembly
520 and the illumination control means 570. Fig 4 is an exploded view of the
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heat sink assembly 500 along with the illumination control means 570. Fig 5
illustrates the heat sink assembly 500 wherein the light source subassembly 520
and the illumination control means 570 are fitted on the heat sink assembly 500.
[0025]A front flange 552, a rear flange 554, and a base plate 556 constitute
body of a single unit heat sink 502. A base plate 554 connects the front flange
552 and the rear flange 554 such that they are placed at a fixed distance from
each other and are parallel to each other. The single unit heat sink 502 is fitted
on the C plate 530 by the fastening members. The C plate 530 is fitted on the
bottom plate 230, thereby stabilizing the complete heat sink assembly 500. The
fastening members are placed in at least four slots 557 having a multi-step
configuration wherein the profile of the slots 557 decreases towards the C plate
530. This configuration provides a leeway for fixing the single unit heat sink 502
according to the desired optical alignment for different types of light sources
intended to be used the heat sink assembly 500. The single unit heat sink 502
can be made of aluminum, copper, alloys, steel and the like.
[0026] In an embodiment of the present invention, as illustrated in Fig. 4 & 5 the
single unit heat sink 502 has three main parts, the front flange 552, the rear
flange 554 and the base plate 556. A base plate 556 connects the front flange
552 and the rear flange 554 such that they are placed at a fixed distance from
each other and are parallel to each other. In various other embodiments of the
present invention the front flange 552 and the rear flange 554 can be arranged
such that there is a flexibility of adjusting the distance including the angle
between the two. This can be achieved by an arrangement for sliding the front
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flange 552 and the rear flange 554 on the base plate 556 with a fixing
arrangement at a desired distance and angle. Adjusting the distance and the
angle between the front and rear flange 552, 554 provides a flexibility to
accommodate different type of light sources and subassemblies.

[0027] The rear flange 554 has an extension member 555 for sliding, holding,
aligning and for removably fitting the light source subassembly 520 on the single
unit heat sink 502. The extension member 555 is configured to be congruent
with the light source holder 526. A hand operated knurl screw (not shown in the
figure) is provided for removably fitting the light source subassembly 520 on the
rear flange 554. As a part of the rear flange 554 and the extension member 555
is open and does not cover the light source holder 526, an a open portion 540 is
formed. The open portion 540 provides a tolerance to accommodate thermal
expansion of the light source holder 526, the rear flange 554 and the extension
member 555.
[0028] The front flange 552 has fins 553 to increase the surface area for
dissipating the heat generated by the light source subassembly 520. The light
generated by the light source 524 is reflected by the reflector 522 towards the
front flange 552 thereby creating a beam of light. Therefore the beam of light
having high amount of heat comes directly in contact with the front flange 552
and transmits the heat to inner side of the front flange 552 and the receptor end
of the fiber optic cable 170 fitted in the fiber optic receptacle 560. The fins 553
situated on the outer side of the front flange 552 readily dissipate the heat. The
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front flange 552 also has a member 566 to fit the illumination control means
570. The front flange provides a stub 564 for accommodating the fiber optic
receptacle 560. The fiber optic receptacle 560 is snuggly fitted on the stub with a
ring member 562 in between. The ring member fits inside the fiber optic
receptacle 560 and has metal balls inserted in the body. The arrangement
creates a snap fit arrangement for the fiber optic receptor end when inserted in
the fiber optic receptacle 560.
[0029] A thermal protection plate 510 covers the single unit heat sink 502 along
with the light source subassembly 520. The thermal protection plate 510 is fitted
on the single unit heat sink 502 by means of at least two hand operated knurl
screws 512. The thermal protection plate 510 has a light protection member 514.
The light protection member 514 essentially blocks the light emitted from the
light source 524 from traveling towards the front panel 210. The thermal
protection plate 510 creates a barrier between the light source 524 and the top
cover 220, blocking the direct transmission of heat to the top cover 220. The
thermal protection plate 510 also helps in dissipating the heat generated by the
light source 524.
[0030]The Illumination control maens 570 is mounted on the front flange 552 by
a mounting block 420 by fixing it in the slot 566. The illumination control means
570 includes a control member 410, a mounting block 420, a motion
transmission means 430, a driving means 580, an elongated limiting member
450, and coupling members 460 and 470. The second coupling member 470
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couples the control member 410 to the mounting block 420. The second coupling
member 470 also connects the motion transmission means 430 to the control
member 410. The motion transmission means 430 is further, coupled to the
mounting block 420 by the coupling first member 460. The first coupling member
460 also connects the driving means 580 to the motion transmission means 430.
In various embodiments of the present invention, the coupling members 460 and
470 are moveably or rotatably coupled to the mounting block 420 and the other
components are attached to the coupling members 460 and 470 using screws,
keyway-pin arrangement, hole-pin arrangements, glue, and the like. Hence, the
movement of the driving means 580 governs the movement of the control
member 410. However, the elongated limiting member 450 is provided to limit
the movement of the driving means 580. As shown in the figure 4, the elongated
limiting member 450 is attached to the mounting block 420. Further, the
elongated limiting member 450 engages with one or more planar members (not
shown in Figure 4) to limit the movement of the driving means 580.
[0031] In an embodiment of the present invention, as illustrated in Fig. 4, the
control member 410 is in form of a circular disc. The disc is centrally attached to
the second coupling member 470 by means of screw. In various embodiments of
the present invention, other means of attaching the control member 410 to th?
second coupling member 470 can be used.
[0032] The second coupling member 470 is in form of a shaft rotatably coupled
to the mounting block 420 by means of bearings, bushings, clips and the like.
The second coupling member 470 is also coupled to the motion transmission
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means 430. In an embodiment of the present invention, the motion transmission
means 430 is a belt drive, as illustrated in Fig. 4. The belt drive includes a set of
toothed gears and a driving belt connecting the gears. One of the toothed gears
is attached to the second coupling member 470. The other toothed gear is
attached to the first coupling member 460. The embodiment of the present
invention illustrates the use of a belt drive for motion transmission, however,
numerous other motion transmission mechanism and their variations may occur
to those skilled in the art, such as, rack and pinion arrangement, a gear drive, a
belt-pulley arrangement, frictional drives, pneumatic transmission system,
hydraulic transmission system magnetic transmission systems and the like.
[0033] The first coupling member 460, as shown in Figure 4, is a shaft rotatably
coupled to the mounting block 420 by means of a bearing, bushing, clips and the
like. As mentioned hereinabove, the motion transmission means 430 is also
attached to the first coupling member 460. Further, the driving means 580 is also
attached to the first coupling member 460. In an embodiment of the present
invention, the driving means 580 is a manually actuated knob. In another
embodiment of the present invention, the driving means 580 is an electric
stepper motor combined with a switch to control the motion. Various other
embodiments of the driving means 580 are known to those skilled in the art, for
example, pneumatic, hydraulic, magnetic, and the like.
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[0034] FIG. 6a and 6b is an illustration of the airflow vents and a supporting
member. The middle panel 600 holds a supporting member 620. The supporting
member 620 has two portions, an open portion 622 and a solid portion 624. The
open portion 622 provides an area for air inflow as well the outflow. The open
portion 622 is geometrically symmetrical arrangement carved out from the solid
portion 624. The solid portion 624 provides strength to the supporting member
620 and platform for a baffle member 630. The baffle member 630 is an array
for vertically arranged liner baffles as shown in the figure 6b. The baffle member
630 is arranged at a particular angle so that the air inflow and outflow is directed
to enhance the efficiency of the cooling arrangement. The airflow configuration
within the light source unit is explained further with help fig 7. The baffle
member 630 is attached to the middle panel 600 with the help of a plate 632.
The baffle member 630 is attached to the middle panel 600 such that the
supporting member 620 is on the outside and the baffle member 630 is on the
inside of the middle panel 600. The baffle member 630 is arranged such that the
airflow is directed on the open portion 622 of the supporting member 620. This
particular arrangement provides maximum open area for ventilation of air in and
out of the light source unit 200. In accordance with the present invention, the
baffle member 630 provides three main functionalities such as, the arrangement
directs the air in proper direction in and out of the light source unit 200, it blocks
the light coming out of the light source unit 200; and it prevents entry of
unwanted subjects inside the light source unit 200. The unwanted subjects could
be like dust particles, paper pieces, and small objects alike.
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[0035] The middle panel 600 provides a first slanted slot 612 for fitting the top
cover 220 by an interlock mechanism. Similarly the bottom 230 is interlocked
with the middle panel 600 at a second slanted slot 614. The middle panel 600
also provides a third slot 618 for fixing the hand operated knurl screw 222. The
middle panel 600 is fitted on the bottom 230 at the attachment member 617 by
a fastening member (not shown).
[0036] Placement of the previously explained components within the light source
unit 200 make a cooling arrangement. In conjunction with Fig. 7, following
paragraphs explain the cooling arrangement and more particularly the airflow
pattern. Fig 7 is a top view of the light source unit 200 without the top cover 220
illustrating the airflow in the light source unit 200.
[0037] The baffle member 630 along with the supporting member 620 allows the
inlet of cool air inside the light source unit 200. A first group of flow indicators
710 provide inlet airflow direction and a second group of flow indicators 750
provide outlet airflow direction. The baffle member directs the incoming cool air
on the electronic subassembly 800 and power supply 240 situated inside PCB
chassis 252 and ballast casing 250 respectively. The front panel 210 and the low
voltage power supply module 242 keep maximum air is contained within the area
surrounded by the PCB chassis 252 and ballast casing 250. A first air block
indicated by 720 denotes this contained air. The heat generated by the electronic
subassembly 800 and the power supply 240 is dissipated to by convention
thereby cooling the components within. In this process the first air block 720 is
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conditioned and moderately heated. Gradually, this first air block 720 is directed
towards cooling module 300. The cooling module 300 sucks the air mainly from
the first air block 720. The cooling module 300 creates a vortex and forcibly
pushes the air in a second air block 730 thereby providing air for cooling the light
source subassembly 520, the illumination control system 570 and the heat sink
502. The thermal protection plate 510, the front flange 552, the rear flange 554
and the base plate 556 create air restriction area and become a boundary wall of
the second air block 730. The air in the second air block 730 is continually
circulated within the block thereby enhancing the heat dissipation from the
surrounding components. The cooling module 300 pressurizes the air contained
in the second air block 730 and the air tries to escape through the baffle member
630 on the air outlet side. The baffle member 630 is arranged such that it
creates positive backpressure by resisting the air outflow from the second air
block 730. Therefore the air remains in second air block 730 for a longer time
and facilitating heat dissipation by convection. This process provides effective
cooling of the heat sink 502, light source subassembly 520 and the illumination
control means 570. Positive backpressure created by the baffle member 630 on
the fan assembly 310 makes operation of the fan silent. The cooling module also
generates a relatively narrow air stream denoted by 740. This stream 740 passes
behind the rear flange 556 and over and below the extension member 555
providing cooling air to the rear flange 554, extension member 555 and the light
source holder 526. The heated air travels through the baffle member 630 on the
outflow side and passes out of the light source unit 200 in a direction shown by
flow indicators 750. A timer circuit 810 is also integrated for controlling the
operation of the fan assembly 310 and light source subassembly 520. The timer
circuit 810 and its functioning is explained in detail in the following paragraphs.
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[0038] FIG. 8 is a schematic representation of the timer circuit for controlling the
active components of the cooling assembly 300. The timer circuit 810 mainly
comprises of a microcontroller 811, a Micro-controller reset circuit 812, a crystal
813, Pair of DIP switches 815, and an EPPROM 814. The timer circuit also
constitutes the indicator 214 along with the electrical isolation circuit 830. The
pair of DIP switches 815 allows settings of the Micro-controller 811 in the range
of 0-250, 250-500, 500-750 & 750-1000 hrs. EPPROM 814 stores the code for
timer circuit 810 and holds all the subroutines used for functioning of the timer
circuit 810. Crystal 813 provides clock frequency to the Micro-controller 811.
Micro-Controller reset circuit 812 helps in write protection of EEPROM,
microcontroller reset & watchdog timer. Transformer 242 provides electrical
energy to the timer circuit 810. The Micro-controller 811 is connected to the
front panel on-off switch 216. The microcontroller 811 is connected to the
indictor 214 through an electrical isolation circuit 830. The indictor 214 has three
LEDs Red, Yellow & Green and the indicator PCB 215. These LED's are interfaced
with Microcontroller 811. The Yellow LED indicates that only 50 hours of the life
of the light source 524 is remaining and that a new light source subassembly 520
is needed for replacement. The Red LED indicates that the life of the light source
524 has ended and needs immediate replacement. The Green LED indicates that
the Light source unit 200 and more specifically the light source subassembly 520
is being cooled and that the cooling assembly 300 should not be switched off
before the Green LED turns off. This cooling of the light source subassembly 520
is essential to improve life of the light source 524. The Green LED also helps the
user to decide when to restart the light source 524 after power cut-off or similar
situations. The following paragraphs explain the working of the timer circuit 810.
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[0039]The number of hours of the life of the light source 524 are set in the
microcontroller 811 using DIP-switches 815. The DIP-switches 815 are connected
to the microcontroller 811 through a port, by programming that port in input
mode. When the front panel on off switch 216 is activated to turn on the light
source 524, it activates the opto-isolator on the PCB, thereby providing a high
signal at port that is selectively programmed as an Input-Output port. This hign
signal activates the counter in the microcontroller 811, which in turn starts
decrementing the set hours value in the microcontroller 811.
[0040] As the count keeps on decreasing, at one time, the count reaches the
window of Low-life (in this case, its 50 hours). When this value is reached, the
microcontroller 811 sends a signal to light up the Yellow LED. As the count gets
further decremented, at one time, the count reaches value of 0 hours. When this
happens, the microcontroller sends a signal to light up the Red LED, indicating
that life of the light source 524 is over. When the new light source subassembly
520 is installed, then life of the light source 524 in the microcontroller 811 has to
be reset, else the microcontroller will continuously keep the current value of
hours as 0, and thus would keep the Red LED flashing.
[0041] The Micro-Controller Reset Circuit (812) connected to the microcontroller
811 runs a RESET subroutine, thereby erasing the values present in all the
variables of microcontroller. New value of hours is set in microcontroller for a
new light source 524. The EEPROM 814 holds all the subroutines that are used to
carry out the necessary actions. The proper subroutine address is calculated and
24
the microcontroller 811 runs that Interrupt-subroutine by jumping to the
appropriate address location.
[0042] Hence, the cooling arrangement has advantages over the above
background arts. Firstly, a cooling arrangement to effectively cool the heated
light source and electrical components fitted in a single compact unit, Secondly,
a cooling arrangement to prevent damage to the fiber optic end, Thirdly to
facilitate cooling of the light source unit after the operation of the heated
components has been switched off and lastly an arrangement to allow onsite
replacement of the light source with proper alignment.
[0043] While the present invention has been illustrated by description of several
embodiments, it is not the intention of the applicant to restrict or limit the scope
of the appended claims to such detail. Numerous other variations, changes, and
substitutions will occur to those skilled in the art without departing from the
scope of the invention.
25
WE CLAIM
1. A ventilation and cooling device (300) in an imaging system (100) for
maintaining an optimum internal temperature within a light source unit
(200), in particular a light source (524) including an electronic circuitry
(800) for enhancing the performance and life of the light source (524)
including the electronic circuitry (800), the imaging system (100)
comprising :
a light source unit (200), a display and recording module (120); a video
connector (126); a camera unit (150), a camera connector (180); a fibre
optic cable (170); and an endoscope (190); the light source unit (200)
comprising a light source subassembly (52) having a light source (524), a
reflector (522), and a bulb holder (526); a heat sink assembly (500)
attached to the light source subassembly (520) for dissipating the
generated heat, a power supply module (240); an electronic subassembly
(800) having a timer circuit (810); an indicator module (214); an
illumination control means (570); and a fibre optic receptable (560)
attached to the heat sink assembly (500), the ventilation and cooling
device comprising :
- a housing (110) for enclosing the light source subassembly
(520), the power supply module (240), the heat sink
module (500), and the electronic subassembly (800);
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- a ballast covering (250) and a PCB - chasis (252) having a
plurality of openings (254) to allow flow of air over the
power supply module (240) and the electronic
subassembly (800);
- a fan assembly (310) for providing ventilation of air inside
the housing (110);
- a thermal protection plate (510) to create an air block;
- a supporting member (620) comprising at least one open
portion (622) and a solid portion (624), the open portion
(622) providing an area for air inflow and outflow, the solid
portion (624) having a baffle member (360) to regulate the
air inflow and outflow; and
- a timer circuit (810) for controlling operation of the fan
assembly (310) including the light source subassembly
(520).
2. The device as claimed in claim 1, wherein the fan assembly (310)
comprising:
- atleast one fan body (314) with ratable blades and a chasis
(312);
- a bracket (330) for fitting the atleast one fan wherein the
bracket (330) is fitted on the housing (110);
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- a dampner (320) for dampening the vibrations of the fan
wherein the dampner (320) is flitted between the fan and
the bracket (330).
3. The device as claimed in claim 1, wherein the single unit heat sink (502)
comprising:
- a front flange (552) and a rear flange (554) connected bv
a base plate (554), wherein the base plate (554) is fitted
on the housing (110);
- means for (562, 564) a receptacle (560) for fitting to a
light transmission element; and
- a knurl screw for removably fitting the light source
subassembly (520) on the rear flange (554).
4. The device as claimed in claim 1 or 3, wherein the light source
subassembly (520) and the fibre optic receptacle (560) for fitting light
transmission element on the single unit heat sink (502) are arranged such
that the required optical alignment is achieved
5. The device as claimed in claim 1,3 or 4, wherein the single unit heat sink,
further comprises a plurality of fins (553) for increasing the surface area
and to act as a heat dissipation unit.
6. The device as claimed in claim 4, wherein the thermal protection plate
(510) covering a single unit heat sink (502) and the light source
subassembly (524).
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7. The device as claimed in claim 1, wherein the air flow vents (254) are
positioned on the housing (110) and are formed of said baffle (630),
baffle (630) directing the flow and blocking the light coming out of the
housing (110), and said support member (620) providing strength to the
array of slits.
8. The device as claimed in claim 7, wherein the support member (620) has
geometrically arranged openings for providing maximum area for air flow.
9. The device as claimed in claim 7, wherein the baffle angle is such that it
creates a positive back pressure on the air passing through the air block.
10.The device as claimed in claim 7, wherein the timer circuit (810) for
controlling the operation of the fan assembly (310) and light source
subassembly (520) comprising:
- a controller (811) for counting the usage information of the
light source subassembly (520);
- a memory (814) for storing the usage information of the
light source subassembly (520); and
- an indicator (214) for providing information regarding
usage, cooling and remaining life of the light source (524).
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11.The device as claimed in claim 1, wherein the housing (110) comprises a
front panel (210) rigidly attached to a bottom plate (230) via a supporting
plate (218), the supporting plate (218) detachably attached via fastening
means to a middle panel (600) through an attachment joining the middle
panel (600).
12.The device as claimed in claim 1, wherein the supporting member (620) is
attached to the middle panel (600).
13.A method of ventilation and cooling a light source and an electronic
circuitry in a ventilation and cooling device as claimed in claim 1 to 12, the
method comprising the steps of:
- arranging the light source and the electronic circuitry on
opposing sides of a cooling module;
- arranging the baffle such that the inlet air is directed on
the electronic circuitry;
- creating a first air block around the electronic circuitry and
the power supply module;
- drawing the air by the fan assembly from the first air block
thereby cooling the electronic circuitry and the power
supply module;
30
- creating a second air block within the heat sink assembly
and forcefully circulating the air in the block for dissipating
the heat by convection;
- creating a positive back pressure by the arrangement of
the baffles at the air outlet zone thereby promoting a silent
operation of the fan assembly; and
- controlling the operation of the ventilation and cooling
device by a timer circuit for effective cooling of the light
source and the electronic circuitry.
14. A ventilation and cooling device in an imaging system for maintaining an
optimum internal temperature within a light source unit, in particular a
light source including an electronic circuitry for enhancing the
performance and life of the light source including the electronic circuitry,
as substantially described herein and illustrated with reference to the
accompanying drawing.

This invention relates to a method and a system for ventilation & cooling
arrangement for a compact visualization system. The cooling arrangement is for
the heat generating components like the high intensity light source and the
electrical assemblies. A timer circuit to control the working of fan to enhance the
performance and the life of the high intensity light source and the electrical
assemblies also accompanies the cooling arrangement.