Light source device with cooling rib

To devise a small light source device in which breaking of the bulb of the light source lamp can be suppressed and in which breaking of the bulb will not damage the window component, a light source lamp supported in a housing by only one of two hermetically sealed tubes at opposite ends of an arc tube, a cooling rib is mounted on a lead pin in the one of the sealed tubes that faces toward the window component and has a larger dimension in the radial direction than the maximum diameter of the opening edge of the light exit opening in the housing. The cooling rib serves to block bulb fragments and should it contact the peripheral edge area of the light exit opening with its edge that faces the window component, due to its size, neither the lead pin nor the cooling rib will contact the window component.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a light source device which is installed and used in a projection device, such as, for example, a projector device of the projection type or the like.

2. Description of the Prior Art

Currently, a type of light source device which is installed in a projection device, such as, for example, a projector device of the projection type or the like, as is shown, for example, inFIG. 5, has an essentially box-shaped housing61which is provided with a light exit opening62, and a light source lamp70which is located in this housing61. The light emitted from this light source lamp70is focused by means of a concave reflector80and is projected via the light exit opening62. In order to increase the efficiency of the light from the light source lamp70, there is, for example, a spherical reflector81in front of the concave reflector80with respect to the light exit direction.

In this light source device60, there is a transparent window component65so that the light exit opening62of the housing61is closed from the outside. This yields a state in which the inside of the housing61is hermetically sealed. Accordingly, in operation of the light source lamp70, the light source Tamp70and the two reflectors80,81, reach an extremely high temperature. Therefore, an arrangement is undertaken in which the light source lamp70and the two reflectors80,81, are cooled by, for example, cooling air being delivered into the housing61via an air inlet opening63for the cooling air supply which is formed in the housing61. InFIG. 5, an evacuation opening64for evacuation of the cooling air is also shown.

For the light source lamp70, a discharge lamp of the short arc type is used which has a bulb which, for example, has an arc tube71and hermetically sealed tubes72A,72B, which border the opposite ends of the arc tube71, and in which an anode75and a cathode76disposed opposite each other in the arc tube71. Additionally, the arc tube71is filled, for example, with xenon gas.

The anode75and the cathode76are each attached and held on the tip of a lead pin77that is made, for example, of a tungsten pin. The respective lead pin77extends into the hermetically sealed tubes72A,72B, along their tube axes to the outside. The base areas thereof project over the outer edges of the hermetically sealed tubes72A,72B. On the outer ends of the hermetically sealed tubes72A,72B, the hermetically sealed tubes72A,72B are sealed on the lead pins77, for example, by graded glass, by which hermetically sealed parts are formed.

In this light source lamp70, a base79is installed in the hermetically sealed tube which is located behind the light exit opening, specifically in the cathode-side hermetically sealed tube72B. This base79is supported in the housing61by a holding component66.

In recent years, there has been a tendency to carry a projection device, in which such a light source device has been installed, back and forth and to use it at different locations. Therefore, there is a need to reduce the size of the projection device, and with respect to the need, it is necessary, for example, to reduce the size of the light source device.

One means for reducing the size of the light source device was, for example, to make the light source lamp inherently smaller. In the case of an arrangement in which simply the light source lamp is made small, in operation of the light source lamp70, the distance between the base area of the anode75and the region of the hermetically sealed tube72A, which region is hermetically sealed, for example, by graded glass on the lead pin77, becomes small, by which the anode75which reaches an extremely high temperature during operation of the light source lamp79approaches the hermetically sealed part. Therefore, the disadvantage arises that the hermetically sealed part reaches a high temperature, and thus, the bulb tends to become damaged.

Against this disadvantage, there is a measure which is described in Japanese utility model JP 2532712 Y2. Here, a cooling rib is placed, for example, on the lead pin which extends projecting to the outside from the hermetically sealed part to prevent the temperature of the hermetically sealed part of the light source lamp from rising. This cools the lead pin.

Another measure is disclosed in commonly owned Japanese patent application JP 2003-132845 A. Here, for example, in the periphery of the lead pin, proceeding from the outer peripheral area of the lead pin, there are several air guide plates arranged in the radial direction at distances relative to one another such that they extend in the axial direction. In the gaps between the lead pin and the air guide plates, cooling air can flow and thus cools the lead pin.

In the above described technology, the effect of cooling of the lead pin can be adequately obtained. However, it was found that the following disadvantage arises in both cases:

In the light source lamp, there are specifically cases in which the bulb breaks during operation, since the internal pressure in the arc tube during operation becomes extremely high. In the light source device60with the above described arrangement, since only one of the hermetically sealed tubes of the light source lamp70, i.e., only the hermetically sealed tube72B, is supported (unilateral support arrangement), there are cases in which the window component65is damaged by the fragments of the bulb flying around and colliding with the window component65. In particular, when the window component is damaged in the state in which the light source device is installed in the projector device, adverse effects are exerted on the devices in the peripheral vicinity of the projector device.

SUMMARY OF THE INVENTION

The invention was devised to eliminate the above described disadvantage in the prior art. Thus, a primary object of the present invention is to devise a small light source device in which breaking of the bulb of the light source lamps can be suppressed, and in which, even in the case of breaking of the bulb, the window component located in the housing is prevented from being damaged.

The above object is achieved as in accordance with the invention in a light source device which comprises the following:a housing in which the light exit opening is formed;a light source lamp which is located in the housing;reflectors which are located in the housing and project the light emitted from the light source lamp onto the light exit opening; anda transparent window component is arranged to close the light exit opening of the housing from the outside; anda feed of cooling air for light source lamp and the reflectors is fed into the housing during operation of the lamp,
by the light source lamp having a bulb which has an arc tube in which there is an opposed pair of electrodes, and hermetically sealed tubes which are connected to opposite ends of the arc tube and extend to the outside, lead pins electrically connected to the electrodes projecting outward from the outer ends of the hermetically sealed tubes, the light source lamp being located in a position in which only the hermetically sealed tube facing away from the light exit direction is supported by the housing, and in which the tube axis of the bulb extends along the light exit direction, and a cooling rib being provided on the one of the lead pins which is positioned upstream of the light exit direction with a larger dimension in the radial direction than the maximum diameter of an opening edge of the light exit opening in the housing at the position at which, in the case of contact of the outer edge area of this cooling rib, is adjacent to the peripheral edge area of the light exit opening with the inside wall of the housing, neither the lead pin nor the cooling rib being in contact with the window component.

In this connection, the term “maximum diameter” means the diameter when the opening edge of the light exit opening is, for example, circular. When the opening edge of the light exit opening has other than a circular shape, such as, for example, the shape of a polygon, this means the maximum dimension in width when the opening edge between two parallels is spanned such that the distance between these parallels becomes maximum. If, for example, the opening edge of the light exit opening is square, the dimensions of the diagonals are meant.

The object of the invention is, furthermore, advantageously achieved in a light source device in that the cooling rib is formed such that several cooling air flow openings extend continuously in the direction of thickness.

The object of the invention is, moreover, advantageously achieved in a light source device in that the cooling rib is formed by two metal plates of different materials coming to rest on one another, one of the metal plates having a good heat conduction characteristic and the other metal plate having a good electrically conductive characteristic.

Action of the Invention

In the light source device in accordance with the invention, a cooling rib is generally installed on the lead pin which is located upstream of the light exit direction of the light source device in which only the hermetically sealed tube located away from the light exit direction is supported, and which lead pin projects from the outer end of the hermetically sealed tube. Therefore, during operation of the light source lamp, sufficient cooling action of the lead pin can be obtained and the hermetically sealed part can be prevented from reaching a high temperature. As a result, the bulb can be prevented from breaking and moreover the size of light source lamp can be reduced.

In addition there is the following action:

Even in the case in which the light source lamp breaks during operation and fragments of it fly around, the cooling rib acts as a stopper, in this way, the lamp fragments vigorously collide with this cooling rib that has a larger dimension in the radial direction than the maximum diameter of the opening edge of the light exit opening in the housing. Thus, it is possible to prevent the fragments of the light source lamp from vigorously colliding directly with the window component. In this way, the window component can be reliably prevented from being damaged.

Because several cooling air flow openings are formed in the cooling rib, each of which extend continuously in the direction of thickness, the contact surface with the cooling air can be enlarged, and therefore, the effect of cooling of the lead pin which is positioned in front of the air exit opening can be reliably obtained to a sufficient degree.

Furthermore, because the cooling rib is formed by two metal plates of different materials coming to rest on one another and by one of the metal plates having a good heat conduction characteristic and the other metal plate having a good electrically conductive characteristic, by the action of one of the metal plates, the heat of the lead pin which is positioned upstream in the light exit direction can be radiated with high efficiency, and therefore, it is possible to reliably prevent the hermetically sealed parts from reaching a high temperature. Moreover, power supply to the light source lamp can be advantageously carried out by the action of the other metal plate.

The invention is described below using several exemplary embodiments shown in the drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIRST EMBODIMENT

FIG. 1is a schematic cross section of the arrangement of one example of the light source device10in accordance with the invention andFIG. 2is a schematic cross section of the arrangement of one example of the light source lamp20for the light source device shown inFIG. 1. The light source device10has an essentially box-shaped housing1, for example, of aluminum, in which is formed a light exit opening12with, for example, a circular opening edge. In this housing11, there are a light source lamp20and two reflectors30,31, which project the light emitted from the light source lamp20via the light exit opening12. The shape of the opening edge of the light exit opening12is not limited to a circular shape.

InFIG. 1, there are an air inlet opening13for feed of cooling air into the housing11during operation of the light source lamp20and an evacuation opening14for evacuating the air which has been fed into the housing11back to the outside.

The housing11has a transparent window component15arranged such that the light exit opening12of the housing11is closed from the outside. In this way, a light exit window is formed. The material of the window component15can be, for example, borosilicate glass or the like.

The light source lamp20has a bulb20A which has, for example, an oval arc tube21which forms an emission space, and hermetically sealed tubes22A,22B, which extend outward from opposite ends of the arc tube21. In the arc tube21, an anode25is located opposite a cathode26, and moreover, the arc tube21is filled with an emission substance, such as a rare gas, e.g., xenon, argon, krypton or the like, or a filler gas of a mixture thereof, and if necessary, mercury and the like.

The anode25and the cathode26are each attached and held on the ends of the lead pins27A,27B, which are, for example, tungsten pins. Each of the lead pins27A,27B extend in the hermetically sealed tubes22A,22B along the tube axes thereof, such that their base areas project from the outer edges of the hermetically sealed tubes22A,22B.

The lead pins27A,27B are sealed in the outer ends of the hermetically sealed tubes22A,22B, by graded glass23, by which hermetically sealed parts231are formed.

The shrunken area221shown inFIG. 2is formed by the hermetically sealed tubes22A,22B being partially reduced in their diameter. A sleeve component28is located in the respective shrunken area221of the hermetically sealed tubes22A,22B and is fused to the shrunken area221. The lead pins27A,27B are each inserted into the middle passage opening of this sleeve component28.

This light source lamp20has a base29on the outer end of the cathode-side hermetically sealed tube22B. Because this base29is held securely by a holding component16which is attached in the housing11, the tube axis of the bulb20A extends along the light exit direction, so that the anode25is positioned upstream of the light exit direction (to the right inFIG. 1).

For the light source device10, a first reflector30formed, for example, of an oval focusing mirror has its first focal point aligned with the radiance spot which is formed between the anode25and the cathode26in the light source lamp20. Moreover, the first reflector30is arranged such that the focal point of the second reflector31, for example, a spherical mirror, that is located in front of the first reflector30with respect to the light exit direction of the light source device10, also is aligned with the radiance spot.

By this arrangement, part of the light radiated by the light source lamp20is projected directly forward or is reflected by the first reflector30and projected forward. Moreover, the light directed forward from the outer edge of the first reflector30and to the outside is returned by the second reflector31to the arc area, and is focused by means of the first reflector30and projected forward.

In the above described light source device10, on the lead pin which is positioned upstream in the light exit direction of the light source lamp20, i.e., on the portion of the anode-side lead pin27A which protrudes from the outer end of the hermetically sealed tube22A, there is a cooling rib40that extends beyond the maximum diameter of the opening edge of the light exit opening12in the housing11, specifically with a larger dimension in the radial direction (total length) than the diameter of the circular light exit opening12.

Specifically, the cooling rib40is located in the position in which neither the outer edge area of this cooling rib40which is opposite the peripheral edge area of the light exit opening12nor the lead pin27A is in contact with the window component15. In this exemplary embodiment, for example, the minimum distance a between the outer edge area of the region which is opposite the light exit opening12of the cooling rib40, and the inside of the window component15is greater than the minimum distance b between the outer edge area of the cooling rib40and the inside wall surface of the housing11, and the anode-side lead pin27A does not project outward beyond the outer edge of the cooling rib40.

The cooling rib40, as is shown inFIG. 3, is formed by two metal plates of different materials coming to rest on one another, one of the metal plates, i.e., the metal plate41, having a good electrically conductive characteristic and the other metal plate42having a good heat conduction characteristic. On the bottom end of metal plate41, there is a tongue (not shown) to which a power supply line is connected. In this way, the metal plate41acts as a power supply component for the anode-side lead pin27A.

The metal plates41,42comprising the cooling rib40are each made altogether essentially rectangular except that their lengthwise (radial direction) middle area has a widthwise tapering gap43(see,FIG. 1) at a side which faces inward toward the lamp20. Moreover, the middle areas of the plates41,42have an arch44which is arc-shaped in opposite directions so that, together, they form a tubular area for receiving the anode-side lead pin27A.

The metal plate41and the other metal plate42are attached by fastener components46with the anode-side lead pin27A clamped by the respective arches44.

The combination of two types of materials of the metal plates comprising the cooling rib40, by way of example, can be a metal plate41made of copper (Cu) with a surface which has been galvanized, for example, with nickel. The other metal plate42can be made, for example, of aluminum (Al).

Several cooling air flow openings45are formed in the cooling rib40so as to penetrate the metal plates41,42, in the thickness direction. In this exemplary embodiment, the cooling air flow openings45are formed at given lattice points, for example, at zig-zag-lattice shaped points in the cooling rib40with the ratio of the total area of the opening area to the area of the cooling rib40being, for example at most 10%.

In this light source device10, the cooling air supplied via the air inlet opening13of the housing11with respect to the surface of the other metal plate42for the cooling rib40is blown in at a given angle of, for example, 45°.

Whether, for example, the cooling rib40is inclined with respect to the air inlet opening13at a given angle or whether the air inlet opening13is provided with a suitable rectifier means for supply of cooling air to the cooling rib40with a given angle is irrelevant. Both arrangements are possible.

In the one above described example of the light source device10, the housing11has a height of 150 mm, a width of 200 mm, a depth of 150 mm, an inside volume of 4500 cm3and a maximum diameter of the opening edge of the light exit opening12of 65 mm to 70 mm. The window component15has a diameter of 75 mm and a thickness of 3 mm. The light source lamp20has a rated lamp wattage of for example, 2 kW, a gas pressure during operation of at least 2 MPa, a total length of 193 mm and a distance L (FIG. 2) between the base area of the anode25and the hermetically sealed part231on the anode side of 30 mm. The metallic plates41,42comprising the cooling rib40have a total length in the radial direction of 110 mm, a thickness of 1 mm, an area of 2500 mm2, an opening diameter of the respective cooling air flow openings45of 3 mm, a number of cooling air flow openings45of36and a total area of the opening area of the cooling air flow openings45of 84 mm2(area ratio to the cooling rib40is 3.4%). The amount of cooling air supplied into the housing11is, for example, 2 m3/minute.

The cooling rib40is installed directly in the light source device10with the above described arrangement, fundamentally in the region of the anode-side lead pin27A, which region projects from the outer end of the hermetically sealed tube22A, the light source lamp20being supported only at the cathode-side hermetically sealed tube22B. Therefore, during operation of the light source lamp20, a sufficient cooling action of the anode-side lead pin27A can be obtained and the hermetically sealed parts231can be prevented from reaching a high temperature. As a result, the bulb20A can be prevented from breaking. As a result, the size of light source lamp20can be reduced by the measure that, for example, the distance L between the base region of the anode25and the hermetically sealed part231is reduced or by similar measures. Specifically the distance L between the base area of the anode25and the hermetically sealed part231can be fixed, for example, at 30 mm or less.

Moreover, it can be obtained that, even in the case in which the bulb20A in the light source lamp20breaks and fragments of it fly around, the cooling rib40acts as a stopper against which the fragments will collide instead of against the window component15, and because it has a larger dimension in the radial direction than the maximum diameter of the opening edge of the light exit opening12in the housing11, in the case of contact with an inside wall of the housing by an outer edge area of the cooling rib40which faces a peripheral edge area of the light exit opening12, neither the cooling rib40nor the lead pin27A on which it is mounted will contact with the window component15. Thus, it is possible to prevent the fragments of the light source lamp20from directly colliding vigorously with the window component15. In other words, the parts which experience the collisions with the fragments are the cooling rib and the housing part which surrounds the window component15. In this way, the window component15can be reliably prevented from being damaged. Therefore, the light source device10with the above described arrangement has no adverse effects on devices in the peripheral vicinity due to damage of the window component15. In the case of an arrangement, for example, of a small projector device, it becomes extremely useful.

Furthermore, because several cooling air flow openings45are formed in the cooling rib40and each extend continuously in the direction of thickness, the contact surface with the cooling air can be enlarged and therefore the effect of cooling of the anode-side lead pin27A can be reliably obtained to a sufficient degree.

Furthermore, because the cooling rib40is formed by two metal plates of different materials, specifically an Al plate and a Cu plate, having come to rest on one another, mainly due to the action of the Al plate which forms the other metal plate42with a good heat conduction characteristic, the heat of the anode-side lead pin27A can be radiated with high efficiency and thus it is possible to reliably prevent the hermetically sealed parts231from reaching a high temperature. Moreover, power supply to the light source lamp20via the cooling rib40can be advantageously carried out by the action of the Cu plate which forms the metal plate41with a good conductive characteristic.

SECOND EMBODIMENT

FIG. 4is a schematic cross section of the arrangement of another example of the light source device in accordance with the invention. Besides the fact that, in the area in which there is a cooling rib51opposite the window component15, the cooling rib of this light source device50has a projection (elevation)52which projects (forward) toward the outside, the same arrangement as the light source device shown inFIG. 1. The same components as the light source device shown inFIG. 1are appropriately provided with the same reference numbers as inFIG. 1.

In this light source device50, as in the light source device10shown inFIG. 1, the cooling rib51which located at a position at which, in the case of contact of the outer edge area of this cooling rib51which is opposite the peripheral edge area of the light exit opening12of the housing11with the inside wall surface of the housing11, neither the lead pin27A nor the projection52of the cooling rib51will contact with the window component15. In this exemplary embodiment, for example, the minimum distance a between the tip of the anode-side lead pin27A and the inside of the window component15is greater than the minimum distance b between the outer edge area of the cooling rib51, except for the projection52, and the inside wall surface of the housing11.

In this light source device50, for example, the anode-side lead pin27A projects from the outer end of the cooling rib51, yielding an arrangement in which the window component15is located on the housing11over a, for example, disk-like spacer55in which an opening is formed which corresponds to the light exit opening12of the housing11. However, the above described state can be implemented using an arrangement like that of the light source device10shown inFIG. 1in which the window component15is located directly on the housing11.

In this way, since the housing11and the cooling rib51must be electrically insulated from one another, it is necessary for the cooling rib51to be spaced a sufficient distance from the housing11.

By the light source device50with this arrangement, however, the cooling rib51can be arranged in the state in which at least part of the projection52extends at its outer end into the space of the light exit opening12of the housing11. Therefore, using a cooling rib51with a sufficient heat radiation area (contact area with the cooling air), an arrangement with a relatively guaranteed electrical insulation property of the housing11and of the cooling rib51from one another can be undertaken. Therefore, basically the same action as in the light source device10with the arrangement shown inFIG. 1can be obtained. Furthermore, because the housing11, specifically the dimension of width of the housing11(dimension in the light exit opening) can be reduced by roughly 1.5% as compared to the light source device shown inFIG. 1, the entire light source device50can be made even smaller.

Embodiments of the invention were described above. However, the invention is not limited to the above described embodiments, and various changes can be made. For example, the shape of the cooling rib is not specially limited to those mentioned so long as the total length in the radial direction is greater than the maximum diameter of the opening edge of the light exit opening in the housing.

Furthermore, the number of cooling air flow openings, the pattern of the positions at which they are formed, and the size of the opening diameter are not specially limited, but can be suitably changed depending on the purpose.

Furthermore, the invention is not limited to a light source device with a light source lamp in which the hermetically sealed arrangement is produced by graded glass, but the invention can be used for a light source device with a light source lamp in which, for example, a hermetically sealed arrangement can be produced by an inner lead pin which supports an anode or a cathode on the tip being connected to an outer lead pin via a metal foil which is hermetically installed in the hermetically sealed part.