Abstract:
A disclosed gaming machine provides a thermal management system comprised of fans, vents and a particular configuration of thermal sources (e.g. CPU, power supply, monitor) and gaming machine components (e.g. printer, coin hopper, etc.). For a given component packaging scheme within the gaming machine cabinet, the thermal management system uses natural convention and a system of fans to cool the gaming machine cabinet by pulling air over the thermal sources and directing the air towards the top of the gaming machine. The pulling action of the fans helps to maintain laminar flow within the gaming machine cabinet which reduces heat transfer with the gaming machine cabinet. Additionally, the fans are configured to prevent dust accumulation on sensitive components such as the CPU and other electronics and to minimize the noise level outside of the gaming machine.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to game playing methods for gaming machines such as slot machines and video poker machines. More particularly, the present invention relates to thermal management systems for gaming machines. 
     There are a wide variety of devices that can comprise a gaming machine such as a slot machine or video poker machine. Some examples of these devices are lights, slot reels, ticket printers, card readers, speakers, bill validators, coin acceptors, display panels, key pads, bonus wheels, and button pads. These devices provide many of the features which allow a gaming machine to present a game. Some of these devices are built into the gaming machine. Often, a number of devices are grouped together in a separate box that is placed on top of the gaming machine. Devices of this type are commonly called a top box. 
     Typically, utilizing a master gaming controller, the gaming machine controls various combinations of devices that allow a player to play a game on the gaming machine and also encourage game play on the gaming machine. For example, a game played on a gaming machine usually requires a player to input money or indicia of credit into the gaming machine, indicate a wager amount, and initiate a game play. These steps require the gaming machine to control input devices including bill validators and coin acceptors to accept money into the gaming machine and recognize user inputs from devices including key pads and button pads to determine the wager amount and initiate game play. 
     As technology in the gaming industry progresses, the traditional mechanically driven reel slot machines are being replaced with electronic counterparts having CRT, LCD video displays or the like. These video/electronic gaming advancements enable the operation of more complex games, which would not otherwise be possible on mechanical-driven gaming machines. For example, in addition to reel slot machines, it is now common to observe stand-alone or multiple platform video electronic games including Keno, Blackjack, Poker, Pai Gow, or slots in even the smallest gaming establishments. 
     Typically, video/electronic gaming machines utilize numerous internal electrical components including, for example, a power supply, a monitor, a communication board, a sound system, a printer and a CPU. During extensive use, and due to the fact that many of these game devices are always “on” even when not being played, many of the internal electrical components require thermal management to prevent premature component failure. For example, CPUs typically generate a significant amount of heat but only operate properly within a specified temperature range. Thus, most CPUs require a thermal management system of some type to prevent the CPU from overheating and failing. 
     Within the gaming industry, the space occupied by a gaming machine is a critical commodity. While the functionality of gaming machines has increased via the introduction of new technology, the space and volume allotted to gaming machines has not increased. Thus, within the relatively constant volume offered by the gaming machine cabinet, newer electronic gaming devices such as printers, monitors and card readers must be packaged with older gaming devices such as coin hoppers, coin acceptors, and lock boxes which are still needed by the gaming machine. 
     With the limited space within the gaming machine cabinet and the addition of electronic components requiring thermal management, packaging to provide both functionality and thermal management is becoming an important issue within the gaming industry. Traditionally, thermal management within gaming machine cabinets has been provided by taking advantage of natural convection. With vents near the top and the bottom of the gaming machine cabinets, internally generated hot air is convected naturally towards the top of the gaming machine where it may be expelled out the top vent. Cool air is naturally drawn into to the gaming machine through the bottom vent. When necessary, this process may be aided by fans within the gaming machine. With mostly mechanical components that tend to be fairly heat tolerant, this simple process is adequate to provide thermal management for a gaming machine. 
     In modern gaming machines, natural convection is still utilized as part of the gaming machine thermal management system. However, with many heat sensitive electrical components, thermal management requires careful packaging and flow path analysis to ensure that local hot spots do not develop within the gaming machine cabinet that may cause an electrical component failure. For example, an electronic board is typically mounted to the back cabinet of the gaming machine. When a local hot spot develops in the back of the cabinet near the electronic board as the result of poor air circulation, the portion of the electronic board near the hot spot may fail. To improve circulation within the gaming machine cabinet and prevent local hot spots, fans are often placed within the gaming machine cabinet. Once a packaging scheme has been developed for the components within gaming machine cabinet, the fans must be carefully located to achieve the desired circulation patterns within the gaming machine cabinet. Often, the placement of fans and the development of a packaging scheme is an iterative process. Further, space limitations typically require the fans to be small and noise limitations require the fans to be quiet. 
     Another problem associated with gaming machine thermal management is that internal particulates and contaminates can often be passed from one internal component to another internal component due to the common circulation of the air. For example, within the gaming machine cabinet, there is often an accumulation of coin dust and other particulates generated from the action of coins with the coin hopper. This dust often consists of metallic particles such as nickel and copper from the coins, and carbon steel from the hopper. As a result, this conductive dust complicates the cooling of internal components. More particularly, fans may circulate the coin dust from within the gaming machine and then distribute and deposit it onto the components being cooled, as well as other internal components which do not require cooling. Such deposition of these conductive particulates may compromise the operation of sensitive components within the gaming machine, and may even cause shorting of circuitry. Thus, dust management is also considered in the thermal management system developmental process. 
     In view of the above, it would be desirable to provide thermal management systems for modern electronic gaming machines which overcome the limitations associated with electronic component heat and dust sensitivity in a gaming machine cabinet with significant space and volume restrictions. 
     SUMMARY OF THE INVENTION 
     This invention addresses the needs indicated above by providing a gaming machine with a thermal management system comprised of fans, vents and a particular configuration of thermal sources (e.g. CPU, power supply, monitor) and gaming machine components (e.g. printer, coin hopper, etc.). For a given component packaging scheme with the gaming machine cabinet, the thermal management system uses natural convection and a system of fans to cool the gaming machine cabinet by pulling air over the thermal sources and directing the air towards the top of the gaming machine. The pulling action of the fans helps to maintain laminar flow within the gaming machine cabinet which reduces heat build up within the gaming machine cabinet. Additionally, the fans are orientated to prevent dust accumulation on sensitive components such as the CPU and other electronics and to minimize the noise level outside of the gaming machine. 
     One aspect of the present invention provides a thermal management system for a gaming machine. The thermal management system can be generally characterized as including 1) a gaming machine cabinet with a front, a back opposite the front, a first side connecting the back and the front, a second side connecting the back and the front, a top and a bottom (there may be a sub-enclosure within the main cabinet), 2) one or more vents in the gaming machine cabinet where the one or more vents allow air from outside the gaming machine to enter the main cabinet enclosure and cool the gaming machine, 3) a monitor mounted within the gaming machine and viewable to a player facing the front of the gaming machine and allows a player to play a game on the gaming machine, 4) a power supply box connected to a motherboard mounted on the back of the gaming machine cabinet, 5) a CPU box connected to or containing the motherboard and a CPU and mounted to the cabinet via a CPU enclosure, 6) a first fan mounted to the power supply where the first fan pulls air through the power supply and thereby cools the power supply, 7) a second fan mounted to the CPU enclosure where the second fan pulls air through the CPU box and thereby cools the CPU box, and 8) a third fan mounted on the top of the gaming machine wherein the third fan pulls hot air rising from the monitor, the CPU and the power supply from the gaming machine cabinet and vents the hot air outside the gaming machine cabinet and thereby cools the gaming machine cabinet. The gaming machine may be a slant top gaming machine or upright gaming machine which provides one or more games such as a video slot game, a video poker game, video pai gow, video keno and video black jack. The fans may each pull a volume of air per unit of time within a specified range, may emit noise within a specified range and may have a diameter within a specified range. In a specific embodiment, the thermal management system may include a monitor shelf, which at least partially supports the monitor. When present, the monitor shelf defines a top side of the sub-assembly. The monitor shelf may contain one or more holes. 
     In preferred embodiments, the CPU box which is mounted on the CPU enclosure includes an inlet CPU box vent where the inlet CPU box vent is on a first side of the CPU box and an outlet CPU box vent where the outlet CPU box vent is on a second side of the CPU box opposite the first side of the CPU box. Typically, air is pulled into the CPU box inlet and across the CPU box to the outlet CPU box vent by the second fan. The air pulled through the CPU box cools a CPU mounted within the CPU box and prevents dust from within the main cabinet enclosure from entering the CPU box. 
     In preferred embodiments, air is typically drawn from outside the gaming machine cabinet through one or more of the main cabinet vents. The main cabinet vents may utilize louvered vent covers. One of the main cabinet vents may be near the inlet CPU box vent or near a power supply box inlet vent. The power supply box may additionally contain an outlet power supply vent on a second side opposite the side with the power supply box inlet vent. The first fan, which is mounted on the second side of the power supply box, pulls air into the power supply through the inlet power supply vent, through the power supply box and out the outlet power supply vent. 
     Another aspect of the invention provides a gaming machine where the gaming machine may be characterized as including 1) a gaming machine cabinet, 2) a monitor mounted within the gaming machine cabinet, 3) a CPU mounted near a first side of the gaming machine cabinet, 4) a power supply for the gaming machine mounted near the first side of the gaming machine cabinet, 5) a coin hopper mounted in the gaming machine cabinet, 6) a first fan mounted near the CPU and orientated to pull air over the CPU and push air toward the hopper and 7) a second fan mounted near the power supply and orientated to pull air over the power supply and toward the coin hopper. The power supply, the coin hopper and the CPU may be located below the monitor such that the orientations of the first and second fans with respect to one or more walls of the gaming machine cabinet cause air to flow upward within the gaming machine cabinet and cool the monitor. 
     In specific embodiments, one or more vents may be located on a first side of the gaming machine cabinet near the CPU and near the power supply. The gaming machine may include a power supply box having vents that encloses the power supply where the second fan is mounted on the power supply box. Also, the gaming machine may include a CPU enclosure having vents and supports a CPU box, which encloses the CPU where the first fan is mounted on the CPU enclosure. 
     Another aspect of the invention provides method of cooling a gaming machine having a monitor, a CPU and a power supply mounted in a gaming machine cabinet. The method may be characterized as including the following sequence: 1) drawing air into the gaming machine cabinet, 2) pulling air over the CPU, power supply and monitor; and 3) venting air out the top of the gaming machine cabinet. In this method, the air is drawn into the gaming machine through one or more vents on a side of the gaming machine cabinet that is near to one or both of the CPU and power supply. The air is drawn over the power supply and CPU and then upward by the monitor and then exits through the top of the gaming machine cabinet. The gaming machine may include a coin hopper that generates coin dust such that the air drawn into the cabinet directs coin dust away from the CPU. 
     These and other features of the present invention will be presented in more detail in the following detailed description of the invention and the associated figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective drawing of a gaming machine having a top box and other devices. 
     FIGS. 2A and 2B are a side view and a perspective drawing of an upright gaming machine with air flow patterns within the gaming machine. 
     FIGS. 3A and 3B are a bottom view and a perspective drawing of slant top gaming machine with air flow patterns within the gaming machine. 
     FIGS. 4A and 4B are a side view and a perspective drawing of power supply box with air flow patterns. 
     FIGS. 5A and 5B are a top view and a perspective drawing of a CPU box with air flow patterns. 
     FIG. 6 is a flow chart depicting a method for cooling a gaming machine. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning first to FIG. 1, a video gaming machine  2  of the present invention is shown. Machine  2  includes a main cabinet  4 , which generally surrounds the machine interior (not shown) and is viewable by users. The main cabinet includes a main door  8  on the front of the machine, which opens to provide access to the interior of the machine. Typically, the main door  8  and/or any other portals which provide access to the interior of the machine utilize a locking mechanism of some sort as a security feature to limit access to the interior of the gaming machine. Attached to the main door are player-input switches or buttons  32 , a coin acceptor  28 , and a bill validator  30 , a coin tray  38 , and a belly glass  40 . Viewable through the main door is a video display monitor  34  and an information panel  36 . The display monitor  34  will typically be a cathode ray tube, high resolution flat-panel LCD, or other conventional electronically controlled video monitor. The information panel  36  may be a back-lit, silk screened glass panel with lettering to indicate general game information including, for example, the number of coins played. The bill validator  30 , player-input switches  32 , video display monitor  34 , and information panel are devices used to play a game on the game machine  2 . The devices are controlled by circuitry (not shown) housed inside the main cabinet  4  of the machine  2 . Many possible games, including traditional slot games, video slot games, video poker, and keno, may be provided with gaming machines of this invention. 
     The gaming machine  2  includes a top box  6 , which sits on top of the main cabinet  4 . The top box  6  houses a number of devices, which may be used to add features to a game being played on the gaming machine  2 , including speakers  10 ,  12 ,  14 , a ticket printer  18  which prints bar-coded tickets  20 , a key pad  22  for entering player tracking information, a fluorescent display  16  for displaying player tracking information and a card reader  24  for entering a magnetic striped card containing player tracking information. Further, the top box  6  may house different or additional devices than shown in the FIG.  1 . For example, the top box may contain a bonus wheels or a back-lit silk screened panel which may be used to add bonus features to the game being played on the gaming machine. During a game, these devices are controlled and powered, in part, by circuitry (not shown) housed within the main cabinet  4  of the machine  2 . 
     The gaming machine is shown with two vents,  42  and  44 . A first vent  42  is located near the bottom of the gaming machine while a second vent  44  is located on the top of the top box  6 . This vent configuration allows cool air into the gaming machine through the bottom vent  42 . As air entering the gaming machine from the bottom vent  42  is heated by components within the gaming machine, it is naturally convected toward the top of the gaming machine where it may exit through the top vent  44 . Typically, the top box  6  will contain a hole or vent which allows hot air from the main cabinet  4  to enter into the top box and exit through the vent  44 . When the top box  6  is removed from the gaming machine, hot air from the gaming machine cabinet may exit from a vent (not shown) on top of the gaming machine. The vent locations may change depending the packaging of components within the gaming machine  2 . The relationship between vent locations and packaging is described with reference to FIGS. 2A,  2 B,  3 A and  3 B. 
     Understand that gaming machine  2  is but one example from a wide range of gaming machine designs on which the present invention may be implemented. For example, not all suitable gaming machines have top boxes or player tracking features. Further, some gaming machines have two or more game displays—mechanical and/or video. And, some gaming machines are designed for bar tables and have displays that face upwards. Those of skill in the art will understand that the present invention, as described below, can be deployed on most any gaming machine now available or hereafter developed. 
     Returning to the example of FIG. 1, when a user wishes to play the gaming machine  2 , he or she inserts cash through the coin acceptor  28  or bill validator  30 . At the start of the game, the player may enter playing tracking information using the card reader  24 , the keypad  22 , and the florescent display  16 . Further, other game preferences of the player playing the game may be read from a card inserted into the card reader. During the game, the player views game information using the video display monitor  34 . 
     During the course of a game, a player may be required to make a number of decisions, which affect the outcome of the game. For example, a player may vary his or her wager on a particular game, select a prize for a particular game, or make game decisions which affect the outcome of a particular game. The player may make these choices using the player-input switches  32 , the video display monitor  34  or using some other device which enables a player to input information into the gaming machine. During certain game events, the gaming machine  2  may display visual and auditory effects that can be perceived by the player. These effects add to the excitement of a game, which makes a player more likely to continue playing. Auditory effects include various sounds that are projected by the speakers  10 ,  12 ,  14 . Visual effects include flashing lights, strobing lights or other patterns displayed from lights on the gaming machine  2  or from lights behind the belly glass  40 . After the player has completed a game, the player may receive game tokens from the coin tray  38  or the ticket  20  from the printer  18 , which may be used for further games or to redeem a prize. Further, the player may receive a ticket  20  for food, merchandise, or games from the printer  18 . 
     FIGS. 2A and 2B are a side view and a perspective drawing of an upright gaming machine with air flow patterns within the gaming machine. In FIG. 2A, the gaming machine cabinet  211  is shown with the cabinet door  246  open. The cabinet door  246  comprises the front of the gaming machine cabinet  211 . The gaming machine cabinet  211  also includes a back opposite the front door  246  and two sides opposite one another connecting the front and the back of the gaming machine  200 . With the cabinet door  246  open, some of the gaming components within the upright gaming machine  200  are exposed. For the purposes of clarity of illustrating the air flow within the gaming machine, all of the gaming machine components that may be mounted within the gaming machine are not shown. For example, a monitor is located in the monitor enclosure  212 . As another example, a coin hopper may be located within the main cabinet enclosure  248  above the drop box slot  236 . 
     The bottom of the upright gaming machine  200  rests on the top of a drop stand  232 . The drop stand contains a drop stand door  244  and a drop box  230 . Typically, a portion of the “house” take, which is a percentage of money or indicia of credit deposited into the gaming machine, is stored in the drop box  230 . The coins or indicia of credit enter the drop box from the main cabinet enclosure  248  via the drop box slot  236 . 
     A top box  204  is resting on the top of the gaming machine  200 . Typically, as described with reference to FIG. 1, a number of gaming devices may be mounted within the top box  204  including a player tracking device, lights, a sound system, a card reader and a printer. To illustrate the air flow patterns within the top box, only the top box cabinet and vents are shown. 
     The monitor enclosure  212  and the cabinet enclosure  248  are the two main enclosures within the gaming machine cabinet  211 . The top of the main cabinet enclosure  248  is a monitor shelf  218  which supports a monitor when it is in the gaming machine  200 . The bottom and the sides of the main cabinet enclosure  248  are portions of the gaming machine cabinet  211 . The front of the main cabinet enclosure  248  is a portion of the cabinet door  246 . A number of gaming components including a bill validator  222 , a lock box  226 , a power supply  238 , a CPU enclosure  240 , a printer (not shown), a CPU box (not shown), and a coin hopper (not shown) may be located within the main cabinet enclosure  248 . The location or packing of each device within the gaming cabinet  211  is important because the gaps and spaces between the devices determine the air circulation patterns within the gaming machine cabinet  211  and main cabinet enclosure  248 . 
     The major thermal sources within the gaming machine cabinet  211  are the CPU, the power supply  238 , and the monitor. The CPU is mounted within a CPU box where the CPU box is designed to fit within the CPU enclosure  240 . The CPU and CPU box are described with reference to FIGS. 5A and 5B. The CPU box and power supply  238  are typically connected to an electronic board mounted on the back of the gaming machine cabinet. Typically, there is a maximum operational temperature for the CPU, the power supply  238  and the monitor. When the maximum operational temperature is exceeded for any of the devices, the device may fail or cease to operate properly. For example, the CPU may begin to malfunction and fail when the temperature within the CPU box exceeds 100° F. 
     To prevent device malfunctions from over-heating, a thermal management system is employed. The thermal management system utilizes the fans, the vents, the packaging/layout of the devices within the gaming machine cabinet and the thermal properties of the devices to prevent any of the devices from overheating. For example, the power supply  238  is contained within a power supply box. A power supply fan  228  is mounted to the power supply box. The power supply box contains an inlet vent and an outlet vent (Details of the power supply box are described with reference to FIGS.  4 A and  4 B). The inlet vent may be placed near a vent  242  on the side of the gaming machine cabinet  211 . The location of the vent relative to the power supply inlet is selected to provide sufficient cooling for the gaming machine components within the cabinet. The distance of the power supply inlet vent to the edge of the nearest vent  242  is usually between about 2 and 4 inches. When the fan is operating, it pulls cool air from outside the gaming machine  200  through the vent  242  and into the power supply through the power supply box inlet and across the power supply. Then, air is drawn through the outlet of the power supply and blown upwards towards the monitor. The air flow patterns across the power supply and towards the top of the gaming machine are indicated by the arrows  234  and  224 . 
     When a CPU box is mounted within the CPU enclosure  240 , a CPU enclosure fan  220  mounted to the CPU enclosure, pulls cool air from a vent on the side of the gaming machine cabinet through a vent  250  or hole in the CPU enclosure  240  and into an inlet in the CPU box. The distance of the CPU inlet vent to the edge of the nearest vent is usually between about  2  and  4  inches. Then, air is drawn across the CPU box, through an outlet on the CPU box, through a hole in the CPU enclosure  240  and pushed outward by the fan. In one embodiment, a fan may be mounted on the outside of the CPU box above the CPU outlet vent. When the air hits the side of the bill validator enclosure, the air is directed towards the top of the gaming machine. The air flow pattern through the CPU box and CPU enclosure is indicated by the arrow  252 . The vent on the side of the gaming machine may be located such that the power supply fan  228  and the CPU enclosure fan  220  draw air in from the same vent  242  or the power supply inlet and the CPU box inlet may each be located near separate vents. 
     The fans are designed to pull air into the gaming machine cabinet  211  to maintain laminar flow which may prevent particulate contamination. When the fans are located on the opposite side of the power supply and the CPU enclosure  240  and push air into the CPU box and the power supply box, the flow patterns tend to become turbulent. Turbulent air flow tends to provide better heat transfer characteristics than laminar flow because the laminar flow leaves a thicker boundary layer of hot air near the surface of a hot component, such as a power supply  238 , while a turbulent boundary layer is thinner and provides more mixing of the hot air near the surface with the air being moved by the fans above the component. A higher mixing rate for the turbulent flow may provide more cooling to a hot component. However, the generally higher mixing rate for the turbulent flow as compared to the laminar flow also tends to allow more contaminants, such as coin dust, to be picked up off the surface of the various components within the gaming machine. When picked up off the surface, the surface contaminants may be deposited on the CPU components or the power supply components causing damage. For example, metallic coin dust may cause shorts within the CPU components. Thus, to minimize particulate contamination, the fans are arranged and sized to maintain laminar flow while still providing the necessary amount of cooling to the components within the gaming machine. 
     Another factor for placing the fans near the interior of the gaming machine and away from the vents on the side of the gaming machine is fan noise. When the fans are placed near the vents, the amount of noise emitted by the fans, which may be perceived by a player playing a game on the gaming machine, is significantly increased. When the fans are too noisy, a player may choose not to play a game on the .gaming machine or may reduce their game play. To reduce fan noise, the location of the fan and the inherent amount of noise of the fan are considered. Other factors considered in fan selection are the size, the cost, and the volume of air moved by the fan per second. For example, the diameter of the power supply fan is usually between about 2 and 3 inches with one embodiment about 2.36 inches and the diameter of the CPU enclosure fan is usually between about 3 and 4 inches with one embodiment about 3.15 inches. Typically, the fans are between about 0.8 and 1.2 inch thick with one embodiment about 1 inch thick. Usually, the fans are mounted in a square enclosure with a length and width about the same diameter of the fan. A few manufacturers of the fans, which may be used in this invention are Delta Electronics, Tapei, Taiwan, Globe Motor, Dayton, Ohio, ebm/PAPST, Farmington, Connecticut or NIDEC/Power General, Canton, Mass. Some operating properties for the power supply fan are an air flow rate of between about 15 and 25 cubic feet a minute (CFM) and a noise level of below 44 decibels (dB) but preferably closer to 30 dB. Some operating properties for the CPU enclosure fan are an air flow rate of between 35 and 45 CFM and a noise level of below 44 dB but preferably closer to 30 dB. These types of fans may be used in other locations of the gaming machine as described below. 
     The power supply fan  228  and the CPU enclosure fan  220  are orientated and placed to move air to through the monitor shelf  218  and by the monitor when it is placed on top of the monitor shelf  218 . The air moving upward past the monitor towards the top of the gaming machine as shown by the arrows  214  tends to cool the monitor. The flow path toward the top of the gaming machine is aided by the natural convection of the hot air. The monitor shelf  218  contains a number of holes  216  which allow air to flow through the monitor shelf. Typically, the shape of the holes are elliptical. The elliptical shape is chosen to minimize the strength lost from cutting holes in the monitor shelf and maximize air flow. 
     After the air rises past the monitor it typically exits the gaming machine cabinet  211  through a vent on the top of the gaming machine. A fan  254  may be located below this vent to push hot air outside of the gaming machine cabinet or the fan may be located at the bottom of the top box  204  to pull air into the top box  204 . The diameter of the fan  254  is usually between about 3 and 4 inches with one embodiment about 3.15 inches. When the top box  204  sits on top of the gaming machine cabinet  211 , the hot air from the gaming machine cabinet may be vented into to the top box as shown by the arrow  208 . Hot air from the top box may exit the top box via one or more vents including  256  and  202 . Hot air exiting from the top box is indicated by the arrow  258 . 
     As mentioned above, the accumulation of metallic dust on sensitive electrical components may cause thermal and electrical problems. The CPU enclosure fan  220  and power supply fan  228  are orientated to prevent coin dust from accumulating on the CPU and the electronic components mounted on the back plane of the gaming machine cabinet  211 . A major source of metallic dust is the coin hopper (not shown) which is typically located above the drop box slot  236 . The air flow patterns  252  and  234  are designed to prevent metallic dust from accumulating on the CPU, the power supply  238  or other sensitive electronic components. 
     FIG. 2B is a side view of the gaming machine in FIG.  2 A. The sides of the top box  260 , cabinet  266 , and drop stand are shown. A vent  270  is located on the side  266  of the gaming machine cabinet. The vent allows cool air  266  from outside the gaming machine  200  to enter the gaming machine cabinet. Typically, the vent  270  utilizes a louvered vent cover. The louvered inlets are added to prevent tampering with the components within the gaming machine. The vent  270  may contain filters to prevent outside dust from entering the gaming machine. The vent  270  is located and sized to provide the proper air flow and cooling to the components within the gaming machine cabinet  211 . In one embodiment, a second vent  271  may be located above the vent  270  with a similar design as vent  270 . Typically, the one or more vents are located near the CPU box and power supply box inlets. However, the vent is usually off-set from the CPU box inlet to prevent tampering with the CPU. Additionally, one or more vents may be utilized on the gaming machine i.e. a first vent may be placed near CPU box inlet and another vent may be placed near the power supply inlet. 
     A second vent  264  may be located on the side of the top box. The vent  264  may allow cool air  262  to enter the top box from outside the gaming machine to enter the top box. The second vent may aid in the natural convection process. The vent is located and sized to provide the necessary cooling and air flow within the top box. However, in some cases, the second vent is not needed and may not be included with the top box. 
     FIGS. 3A and 3B are a side view and a perspective drawing of slant top gaming machine with air flow patterns in the gaming machine. In FIG. 3A, the gaming machine cabinet  311  is shown with the front of the cabinet exposed. Typically, a door (not shown) and other gaming machine components are used to cover the front of the cabinet  311 . The gaming machine cabinet  311  also includes a back opposite the front door and two sides opposite one another connecting the front and the back of the gaming machine  300 . With the front door removed, some of the gaming components within the slant top gaming machine  300  are exposed. For the purposes of clarity of illustrating the air flow within the gaming machine, all of the gaming machine components that may be mounted within the gaming machine are not shown. For example, a printer is usually located in the main cabinet enclosure  328  or coin hopper is usually located in the hopper enclosure  318 . 
     The bottom  327  of the slant top gaming machine  300  rests on the top of a drop stand  316 . The drop stand contains a drop stand door  322  and a drop box (not shown). Typically, a portion of the “house” take, which is a percentage of money or indicia of credit deposited into the gaming machine, is stored in the drop box. A top box  302  is resting on portion of the top of the gaming machine  300 . Typically, as described with reference to FIG. 1, a number of gaming devices may be mounted within the top box  302  including a player tracking device, lights, a sound system, a card reader and a printer. To illustrate the air flow patterns, only the top box cabinet and vents,  344  and  350 , are shown. 
     The top of the gaming machine cabinet  311  is comprised of the portion supporting the top box  302 , the flat area containing the input buttons  338  and the coin tray  310 , and the slanted area around the monitor  340  and the bill validator  306 . A top hatch door  341 , which prevents the monitor  340  from being lifted out of the cabinet  311 , is comprised of the flat area with the input buttons  338  and the slanted area over the monitor  340 . The top hatch door  341  is hinged where the slanted area over the monitor  340  and the flat area supporting the top box  302  intersect and opens upwards. 
     The hopper enclosure  318  and the main cabinet enclosure  328  are the two main enclosures within the gaming machine cabinet  311 . The top of the main cabinet enclosure  328  is the top hatch  341 , which secures the monitor  340  when it is in the gaming machine  300 . The bottom and sides of the main cabinet enclosure  328  are portions of the gaming machine cabinet  311 . Also, one side of the main cabinet enclosure  328  may be one side of the hopper enclosure  318 . The front of the main cabinet enclosure  328  is a portion of the front door (not shown) and possibly the front of a gaming device such as a printer. A number of gaming components including a power supply  324 , a CPU enclosure  332 , a printer (not shown), a CPU box (not shown), and a monitor  340  may be located within the main cabinet enclosure  328 . The location of each device is important because the gaps and spaces between the devices determine the air circulation patterns within the gaming machine cabinet  311  and the main cabinet enclosure  328 . 
     The major thermal sources within the gaming machine cabinet  311  are the CPU, the power supply  324 , and the monitor  340 . The CPU is mounted within a CPU box where the CPU box is designed to fit within the CPU enclosure  332 . The CPU and CPU box are described with reference to FIGS. 5A and 5B. The CPU box and power supply  324  are typically connected to an electronic board mounted on the back of the gaming machine cabinet  311 . Typically, there is a maximum operational temperature for the CPU, the power supply  324  and the monitor  340 . When the maximum operational temperature is exceeded for any of the devices, the device may fail or cease to operate properly. For example, the monitor  340  may begin to malfunction and fail when the temperature within the monitor enclosure exceeds 100° F. 
     To prevent device malfumctions from over-heating, a thermal management system is employed. The thermal management system utilizes the fans, the vents, the packaging and the layout of the devices and the thermal properties of the devices to prevent any of the devices from overheating. For example, the power supply  324  is contained within a power supply box. A power supply fan  314  is mounted to the power supply box. The power supply box contains an inlet vent and an outlet vent (Details of the power supply box are described with reference to FIGS.  4 A and  4 B). The power supply inlet vent is near vents or holes  330  on the bottom of the gaming machine cabinet  311 . The location of the vent relative to the power supply inlet is selected to provide sufficient cooling for all of the gaming machine components within the cabinet. The distance of the power supply inlet vent to the edge of the nearest vent  334  is usually between about 1 and 2 inches. In one embodiment, the distance is about 1.5 inches. When the fan is operating, it pulls cool air  325  from the drop stand  316  through the vents  330  and into the power supply  324  through the power supply box inlet and across the power supply. Then, air is drawn through the outlet of the power supply and blown upwards towards the monitor  340 . The air flow patterns across the power supply and towards the top of the gaming machine are indicated by the arrows  320 . 
     When a CPU box is mounted within the CPU enclosure  332 , a CPU enclosure fan  312  mounted to the CPU enclosure, pulls cool air rising from the bottom of the gaming machine cabinet  311  from the vent holes  330  through a vent  334  or hole in the CPU enclosure  332  and into an inlet in the CPU box. The distance of the CPU box inlet vent to the edge of the nearest vent  334  is usually between about 9 and 11 inches. In one embodiment, the distance is about 10 inches. Then, air is drawn across the CPU box, through an outlet on the CPU box, through a hole in the CPU enclosure  332  and pushed outward by the CPU enclosure fan  312 . When the air from the fan impacts the side of the hopper enclosure  318 , the air is directed towards the top of the gaming machine  300 . The air flow pattern through the CPU box and CPU enclosure  332  is indicated by the arrow  336 . 
     The fans are designed to pull air into the gaming machine cabinet  311  to maintain laminar flow. When the fans are located on the opposite side of the power supply  324  and the CPU enclosure  332  and push air into the CPU box and the power supply box, the flow patterns tend to become turbulent. When the gaming machine is operating, the turbulent flow patterns significantly reduce the amount of cooling provided by the fans and tend to raise the temperature of the main cabinet enclosure  328 . 
     Another factor for placing the fans near the interior of the gaming machine and away from the vents on the side of the gaming machine is fan noise. When the fans are placed near the exterior of the gaming machine, the amount of noise emitted by the fans, which may be perceived by a player playing a game on the gaming machine, is significantly increased. When the fans are too noisy, a player may choose not to play a game on the gaming machine or may reduce their game play. To reduce fan noise, the location of the fan and the inherent amount of noise of the fan are considered. Other factors considered in fan selection are the size, the cost, and the volume of air moved by the fan per second. For example, the diameter of the power supply fan is usually between about 2 and 3 inches with one embodiment about 2.36 inches and the diameter of the CPU enclosure fan is usually between about 3 and 4 inches with one embodiment about 3.15 inches. Usually, the fans are mounted in a square enclosure with a length and width about the same diameter of the fan. Typically, the fans are about 1 inch thick. A few manufacturers of the fans, which may be used in this invention are Delta Electronics, Taipei, Taiwan, Globe Motor, Dayton, Ohio, ebm/PAPST, Farmington, Conn. or NIDEC/Power General, Canton, Mass. Some operating properties for the power supply fan are an air flow rate of between about 15 and 25 cubic feet a minute (CFM) and a noise level of below 44 decibels (dB) but preferably closer to 30 dB. Some operating properties for the CPU enclosure fan are an air flow rate of between 35 and 45 CFM and a noise level of below 44 dB but preferably closer to 30 dB. 
     The power supply fan  314  and the CPU enclosure fan  312  are orientated and placed to move air to through the CPU monitor shelf  332  (and CPU box) and direct it upwards and over the bottom of the monitor  340  and then towards the back of the gaming machine  300  where the air exits through the vent hole  342  into the top box  302 . The air moving around the monitor  340  towards the top of the gaming machine tends to cool the monitor  340 . The monitor  340  is encased in a box with many holes which allows air to flow by the thermal sources generated by the various monitor components. The flow path toward the top of the gaming machine is aided by the natural convection of the hot air rising to the top of the gaming machine cabinet  311 . 
     After the air rises past the monitor it typically exits the gaming machine cabinet  311  through a vent on the top of the gaming machine  300 . A fan  304  may be located below this vent to push hot air outside of the gaming machine cabinet or the fan may be located at the bottom of the top box to pull air into the top box  302 . The diameter of this fan  304  is usually between about 3 and 4 inches with one embodiment about 3.15 inches. When the top box  302  sits on top of the gaming machine cabinet  311 . The hot air from the gaming machine cabinet may be vented into to the top box  302  as shown by the arrow  346 . Hot air from the top box may exit the top box via one or more vents including  344  and  350 . Hot air exiting from the top box is indicated by the arrow  352 . The vent  344  may also allow cool air from outside the top box to enter the top box  302 . The venting of hot air outside the top box  302  may be aided by a fan  303  located below the vent  350  on top of the top box. Typically, this fan may emit less noise than the fans located in the interior of the gaming machine because it is close to the exterior of the gaming machine. 
     As mentioned above, the accumulation of metallic dust on sensitive electrical components may cause thermal and electrical problems. The CPU enclosure fan  332  and power supply fan  314  are orientated to prevent coin dust from accumulating on the CPU and the electronic components mounted on the back plane of the gaming machine cabinet  311 . A major source of metallic dust is the coin hopper (not shown) which is typically in the hopper enclosure  318 . The air flow patterns  320  and  336  are designed to prevent metallic dust from accumulating on the CPU, the power supply  324  or other sensitive electronic components. 
     FIG. 3B is a bottom view of the drop stand in FIG.  3 A. The bottom of the drop stand  316  is shown. Three vents  354  are located on the bottom of the drop stand near the back of the gaming machine cabinet  311 . The vents  354  allow cool air  356  outside the gaming machine  300  to enter the drop stand  316 . The vents  330  on the bottom of the gaming machine cabinet  311  are typically aligned with the vents  356  on the bottom of the drop stand  318 . These vents allow cool air from the drop stand to rise into the main cabinet enclosure  328  as indicated by the arrows  325 . 
     FIGS. 4A and 4B are a side view and a perspective drawing of power supply box with air flow patterns. The power supply  400  is encased in a power supply enclosure  401 . Typically, the power supply enclosure  401  is a six-sided rectangular box. A box with similar dimension may be used in the upright gaming machine  200  or the slant top gaming machine  300 . Thus, the power supplies,  238  and  324 , may be interchangeable. However, the orientation of the boxes in gaming machines  200  and  300  may be different. For example, In FIG. 2A, the bottom of the power supply  414  is near the side of the gaming machine. In FIG. 3A, the bottom of the power supply  414  is near the bottom of the gaming machine. 
     In FIG. 4B, the bottom side of the power supply enclosure  414  is comprised of perforated sheet metal with a large number of power supply inlets  412  that allows air  410  to enter into the enclosure  401 . Typically, the power supply inlets  412  are circular holes. A fan  406  mounted to the power supply box over the outlet vent draws air  408  into the power supply inlets and pushes the air  404  away from the power supply  400 . An outlet vent from the power supply is located behind the fan. Typically, the diameter of the fan  406  does not extend beyond the edge of the top of the enclosure side on which it is mounted. 
     FIGS. 5A and 5B are a top view and a perspective drawing of a CPU box with air flow patterns. As described with reference to FIGS. 2A and 3A, the CPU box  500  is typically a rectangular enclosure which rests in the CPU shelves,  240  and  332 . The CPU box encloses a CPU board  510  which controls the operation of many of the gaming devices on the gaming machine and allows the gaming machine to present a game. The CPU box is designed to be removable from the gaming machine. In FIGS. 2A and 3A, the CPU box  500  for the upright gaming machine  200  and for slant top gaming machine  300  may be similar such that a CPU box may be removed from an upright gaming machine  200  and used in a slant top gaming machine  300 . 
     In general, the CPU in the CPU box  500  is a large thermal source. Thus, as described in FIGS. 2A and 3A, a fan mounted on the side of the CPU enclosure is designed to pull air  506  into the CPU box inlet, pull air  516  across the CPU board  510 , and pull air  502  out the CPU outlet vent  504 . In one embodiment, a fan (not shown) may be located above the CPU outlet vent. From the CPU box top view  512 , a fan  514  on top of the CPU is shown. The fan  512  provides additional cooling to the CPU. Typically, the fan may be between about 3 and 4 inches in diameter and pull between about 35 and 45 CFM. In one embodiment, the diameter of the fan 3.15 inches. Typically, the thickness of the fan is about 1 inch. Some manufactures of fans of this type have been previously described. In one embodiment, the fan is directly mounted on the outside of the CPU box outlet. In another embodiment, the fan is mounted above the CPU. Some operating properties for the CPU enclosure fan are an air flow rate of between 35 and 45 CFM and a noise level of below 44 dB but preferably closer to 30 dB. 
     FIG. 6 is a flow chart depicting a method for cooling a gaming machine. In step  600 , air is drawn through one or more vents or holes of some type into to the gaming machine cabinet. Usually, the vent of hole is located near the bottom of the gaming machine cabinet. It is assumed that the air outside the gaming machine cabinet near the vents is cooler than the air inside the gaming machine cabinet. In step  610 , the air is pulled over the major thermal heat sources including the CPU, monitor and power supply using a combination of natural convection and fans to circulate the air. The air flowing over these devices removes excess heat emitted from the devices. In step  620 , hot air from inside the gaming machine cabinet is vented outside the gaming machine cabinet from a vent typically located near the top of the gaming machine. The heat expelled with the hot air helps to a maintain a proper thermal balance within the gaming machine cabinet and hence prevents devices located within the gaming machine cabinet from overheating. 
     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. For instance, while the gaming machines of this invention have been depicted as having top box mounted on top of the main gaming machine cabinet, the use of gaming devices in accordance with this invention is not so limited. For example, gaming machine may be provided without a top box.