Lamp for projector and liquid crystal projector

[0001] [Technical field to which the invention belongs] The present invention relates to a cooling device, and more particularly to a cooling device for a lamp for a liquid crystal projector. [0002] [Conventional technology] Lamps for light sources such as projectors are generally cooled by using air, as described in JP-A-10-23355 and JP-A-9-185124, for example. On the other hand, in the one described in Japanese Patent Application Laid-Open No. 11-282361, the entire heating element including the lamp of the projector is arranged in the closed flow path, the liquid is circulated in the closed flow path by a pump, and the extracted heat is heated. It is cooled by a exchanger. Further, in order to improve the heat dissipation of the lamp as a lighting fixture, a covering body is provided, and a hole for natural air cooling is provided therein. [0003] [Problems to be Solved by the Invention] In the above-mentioned conventional technology, as cooling of the lamp for the projector, noise increases due to the presence of useless cooling air, the reliability of the lamp decreases due to the possibility of liquid leakage to the lamp side by using the liquid as a cooling medium, and the projector case portion. The temperature rise has become a problem, and no consideration has been given to that point. [0004] An object of the present invention is to suppress a temperature rise of a projector case portion due to a projector lamp and to reduce noise of the apparatus itself. [0005] [Means for solving problems] As a first means for solving the above problems, the inventors are configured to be installed in the lamp cover and cooled by cooling air supplied from the outside of the lamp cover in a direction intersecting the lamp optical axis. In a light source lamp for a liquid crystal projector, a heat shield is provided between the lamp body, which is a heating element, and the lamp cover, and radiant heat transmitted from the lamp body to the lamp cover and further to the surface of the projector case via the lamp cover is transmitted. Reduced. [0006] Further, in a liquid crystal projector, cooling air is generally supplied to a light source lamp, and the heat generated by the light source lamp is removed by the cooling air. However, of the cooling air, the cooling air that flows in contact with the outer peripheral surface of the lamp body exchanges heat with the lamp body to remove heat, but the cooling air that flows away without contacting the outer peripheral surface of the lamp body is with the outer peripheral surface of the lamp body. It does not contribute much to the heat exchange of the lamp, and it passes through without any effort. Therefore, in order to effectively utilize the cooling air for cooling, it is sufficient to increase the amount of cooling air flowing in contact with the outer peripheral surface of the lamp body. The inventors have adopted a shape and arrangement in which the heat shield plate functions as a cooling air baffle plate so that the cooling air flowing into the lamp cover does not pass through a position away from the outer peripheral surface of the lamp body. .. [0007] That is, the second means of the present invention for solving the above problems is, in the first means, in a cross section in which the heat shield plate is parallel to the inflow direction of the cooling air into the lamp cover and includes the lamp optical axis. It is characterized by having a curved surface along the outer peripheral contour line of the lamp body, and arranging the heat shield plate close to the outer peripheral surface of the lamp body. [0008] With this configuration, the flow path of the cooling air between the heat shield plate and the outer peripheral surface of the lamp body, that is, the gap between the heat shield plate and the outer peripheral surface of the lamp body is made uniform and smaller, and the outer peripheral surface of the lamp body is made uniform and smaller. It was possible to reduce the amount of cooling air that does not participate in heat exchange between the air and the cooling air. In this way, the cooling air can be effectively used, the cooling fan can be rotated at a low speed, and the cooling fan can be miniaturized, so that the noise and miniaturization of the projector can be realized. [0009] The third means of the present invention is the second means in which a plurality of heat shield plates are arranged in parallel with each other. By arranging a plurality of sheets, the heat shielding effect can be improved and the temperature rise of the projector case can be avoided. [0010] The fourth means of the present invention is, in the second or third means, downstream of the lamp body with respect to the cooling air of the heat shield plate arranged at least at the position closest to the lamp body among the heat shield plates. The side portion is characterized by having a shape along the outer peripheral surface of the lamp body in a plane orthogonal to the optical axis of the lamp. With such a configuration, the area where the cooling air exchanges heat with the outer peripheral surface of the lamp body becomes wide, and the heat transfer efficiency is improved, so that the air volume can be reduced and the noise caused by the blowing means is effectively reduced. [0011] The fifth means of the present invention faces the heat shield plate at the position farthest from the lamp body among the heat shield plates in any of the second to fourth means. It is characterized in that a cooling air inflow limiting means for limiting the inflow of cooling air between the wall surfaces of the lamp cover is provided. When the cooling air flows between the heat shield plate located farthest from the lamp body and the wall surface of the lamp cover facing the heat shield plate, the cooling air does not come into contact with the lamp body and therefore does not come into contact with the lamp body. It is a wasteful wind that does not contribute much to the cooling of the lamp body. The cooling air is effectively used by preventing the cooling air from flowing in such an area and instead allowing the cooling air to flow in the area where the cooling air flows more in contact with the lamp body. In this way, the cooling air can be effectively used, the cooling fan can be rotated at a low speed, the cooling fan can be miniaturized, and the projector can be reduced in noise and size. The sixth means of the present invention guides a larger amount of cooling air to the lamp neck portion, which tends to become hot in the lamp body, than the other portions in any of the second to fourth means. As described above, the cooling air is prevented from flowing to the region partitioned by the heat shield plate that does not contribute to the cooling of the lamp, and that portion is guided to the lamp neck portion. With this configuration, the temperature of the lamp neck portion can be lowered, and the temperature of the lamp itself can be reduced. [0012] The seventh means of the present invention comprises a light source lamp built in a lamp cover, and a blowing means for supplying cooling air to the light source lamp from a direction intersecting the lamp optical axis. In a liquid crystal projector that projects an image formed on a liquid crystal panel onto a projection surface using the light emitted from the light source lamp, the light source lamp is placed in any of the first to sixth means. It is the lamp for the liquid crystal projector described. [0013] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention and their effects will be described. First, FIG. 1 is a liquid crystal projector according to the first embodiment of the present invention. The liquid crystal projector 1 includes a lamp 2 as a light source, a panel 3 for displaying red, green, and blue images, a propeller fan 5 for removing heat from the lamp 2, and a sirocco for heat dissipation of the panel 3. There is a fan 6, each element of the panel section, a propeller fan 5, and a power supply section 4 that supplies electricity to the sirocco fan 6. These components are housed in a box-shaped projector case. [0014] As shown in FIG. 2, the lamp 2 is a lamp body and a lamp composed of a lamp neck portion 11 which is coupled to a vacuum container 2a and a vacuum container 2a having a light emitting portion and has a conductor connected to the light emitting portion. It is composed of a lamp cover 10 for incorporating the main body and a plurality of heat shield plates 9 arranged between the lamp main body and the lamp cover 10. [0015] The light 7 emitted from the lamp 2 passes through the mirror and the panel portion 3 and irradiates the screen and the like. [0016] The cooling air 8 is sucked from the side surface of the sirocco fan 6, discharged to the ceiling plate of the projector case through the panel portion 3, and discharged to the outside air by the propeller fan 5. Further, the cooling air 8 that has entered from the side surface of the power supply unit 4 passes through the propeller fan 5 and is discharged to the outside air through the lamp 2. [0017] As for the amount of heat generated by the projector 1, the amount of heat generated by the lamp 2 is the largest. Therefore, the temperature of the projector case (housing case) in the vicinity of the lamp 2 is higher than that of the other parts. The temperature of the housing case near the lamp 2 rises due to heat radiation and heat conduction from the lamp 2. Therefore, by providing the heat shield plate 9 on the lamp 2, it is possible to prevent the lamp 2 from being exposed to heat and reduce the temperature of the housing case. As the heat shield plate 9, a material that can withstand high temperatures, for example, an aluminum plate or a stainless steel plate is suitable. The thickness may be about 1 mm. [0018] FIG. 2 shows a cross-sectional view of the projector 1 of FIG. 1 around the lamp 2. The lamp 2 is housed in the lamp cover 10, and the lamp 2 is mounted on the projector 1 in the form of being housed in the lamp cover 10. The user can replace the lamp 2 of the projector 1 by attaching and detaching the lamp cover 10. Therefore, when the temperature of the lamp cover 10 is high due to the heat of the lamp 2, it is necessary to stop and wait for the time until the temperature of the lamp cover 10 drops when the lamp 2 is maintained. However, in the present embodiment, the temperature of the lamp cover 10 can be lowered by the heat shield plate 9, so that the maintenance time can be shortened. [0019] Further, the lamp 2 generally used as a light source of a projector produces light by joining the terminals built in the vacuum vessel 2a, and the amount of heat generated in this portion is the highest. The portion where the lead wire for supplying electric power to the terminal penetrates the vacuum container 2a is called a lamp neck 11, and is formed of an insulating material containing the lead wire. That is, since the heat of the light emitting portion is transmitted to the insulating material through the lead wire, the lamp neck 11 tends to become hot even in the lamp body. [0020] In the present embodiment, the heat shield plate 9 is curved along the shape of the lamp 2 as shown in FIG. 2 so that the cooling air can easily flow through the lamp neck 11. FIG. 2 shows a cross section of the lamp 2 cut along a plane including its optical axis (the internal configuration of the lamp body is not shown), and heat shield plates 9 are placed on the upper side and the lower side of the lamp body, respectively. It shows that they are arranged one by one. The heat shield plate located closest to the lamp body has a cross-sectional shape along the contour line of the cross section of the lamp body cut by a plane including its optical axis, and at the illustrated cross-sectional position, with the outer peripheral surface of the lamp body. Are arranged so that the intervals between the two are almost constant. It is desirable to reduce the size (dimension) of the interval, but if it is too small, the pressure loss will increase and the power consumption of the propeller fan 5 will increase, and if it becomes too large, the wasteful cooling air cannot be reduced. It is desirable to confirm the appropriate size of the interval by experiments. [0021] [0021] FIG. 3 is a cross-sectional view taken along the line AA of FIG. In the figure of the lamp cover 10, the cooling air can freely pass through the left and right surfaces. As shown in FIG. 3, the cross sections of the heat shield plates 9a and 9b (and the heat shield plates 9c not shown) cut by a plane orthogonal to the lamp optical axis are the inflow of the cooling air 8 into the lamp cover 10. The cross section in a plane parallel to the direction and orthogonal to the inflow direction of the cooling air 8 into the lamp cover 10 including the lamp optical axis is a curved surface along the contour line of the lamp body. That is, as shown in FIG. 3, the cooling air flowing in between the pair of heat shield plates 9a arranged closest to the lamp body at the top and bottom of the lamp body is the outer peripheral surface of the lamp body and the heat shield 9a. It flows into the gap formed between them and passes at an increased speed. By increasing the speed, the heat transfer coefficient is improved, and since the gap is made uniform in the optical axis direction of the lamp, cooling in the longitudinal direction of the lamp is made uniform. Further, since the cooling air flowing between the heat shield plates 9a is regulated by the heat shield plate 9a so as not to pass through a place away from the lamp body, it is a waste that does not contribute to the cooling of the lamp 2. Cooling air 8 (cooling air flowing outside the heat shield plate 9a) can be reduced. [0022] FIG. 4 shows a cross-sectional view taken along the line BB in FIG. The heat shield plate 9a can supply high-speed cooling air 8 even at the lamp neck 11. Further, in the present embodiment, the cooling air 8 is applied to the outermost region of the lamp cover 10 (between the upper heat shield plate 9c and the upper surface of the lamp cover and between the lower heat shield plate 9c and the bottom surface of the lamp cover). Wasteful cooling air 8 is eliminated by not supplying it and sending more to the inside of the heat shield plates 9b and 9a. Therefore, the rotation speed of the cooling fan can be reduced to a low speed, or the cooling fan itself can be made smaller. As a result, the noise of the projector can be reduced. [0023] To prevent the cooling air from flowing into the outermost region of the lamp cover 10, that is, the region outside the heat shield plate located at the position farthest from the lamp body, the lamp cover shown on the left side of FIG. 4 is used. The part of the wall surface indicated by "X" (the part indicated by "X" in FIG. 2) was closed by providing a lid as a means for limiting the inflow of cooling air. Instead of closing with a lid, as shown in FIG. 5, each heat shield may be bent and arranged in a funnel shape so that the cooling air smoothly flows into the lamp cover. With this configuration, the air volume supplied to the portion corresponding to the lamp neck can be substantially increased, and the cooling efficiency of the lamp neck can be improved. [0024] Next, FIG. 6 shows the measurement results of the temperature of each part in the present embodiment. The horizontal axis is the supplied cooling air volume, and the vertical axis is the lamp temperature 12 and the housing case temperature 13. The broken line is the conventional example, and the solid line is the case of the present embodiment. By providing the heat shield plate 9 between the lamp 2 and the lamp cover 10, the temperature of the lamp temperature 12 and the temperature of the housing case 13 are lowered with respect to the same cooling air volume. The lamp temperature 12 in the present embodiment is due to the fact that the heat shield plate 9 functions as a baffle plate to increase the wind speed on the surface of the lamp 2 and improve the heat transfer coefficient. In addition, the heat shield plate 9 blocks the radiant heat, suppresses the amount of heat radiated to the housing surface, and reduces the housing case temperature 13. The amount of decrease in the lamp temperature 12 and the housing case temperature 13 varies depending on the shape and the number of heat shield plates 9. [0025] Next, a second embodiment of the present invention is shown in FIG. The heat shield plates 9a and 9b on the semicircular side, which are downstream of the cooling air of the lamp 2, are bent in the direction along the outer peripheral surface of the lamp body. As a result, the wind speed of the cooling air flowing along the outer peripheral surface on the downstream side of the semicircle of the lamp body increases, and the heat transfer coefficient is improved. As a result, it is possible to reduce the air volume as a whole, rotate the cooling fan at a low speed, reduce the size of the cooling fan, and reduce the noise and size of the projector. Further, the space between the lamp cover 10 and the heat shield plate 9 becomes wider on the downstream side of the vacuum container semicircle of the lamp 2, and the rise in the surface temperature of the lamp cover 10 due to heat conduction is reduced. Therefore, the lamp temperature and the housing case temperature can be reduced. [0026] [Effect of the invention] According to the present invention, it is possible to obtain the effect of suppressing the temperature rise of the projector case portion due to the projector lamp and reducing the noise of the projector itself. [Simple explanation of drawings] FIG. 1 is a perspective view showing a first embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of the lamp portion shown in FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2. FIG. 4 is a cross-sectional view taken along the line BB of FIG. 2. FIG. 5 is another example of a cross-sectional view taken along the line BB in FIG. 2. FIG. FIG. 6 is a conceptual diagram showing a comparison between the lamp temperature and the housing case temperature with respect to the cooling air volume in the embodiment shown in FIG. 1 and the prior art. FIG. 7 is a cross-sectional view showing a second embodiment of the present invention. [Explanation of symbols] 1 projector 2 lamps 2a vacuum container 3 Panel part 4 Power supply 5 Propeller fan 6 Sirocco fan 7 light 8 Cooling air 9a, 9b, 9c heat shield 10 lamp cover 11 Lamp neck