Projection device and method for positioning display element assembly

Abstract

In the present invention, a heat sink for cooling a liquid crystal display element is fixed to the liquid crystal display element. The heat sink is covered with a cap (10) that reduces a cooling effect of the heat sink on the liquid crystal display element. At least two recessed portions (202) are formed in one or more fins of the heat sink to engage with engaging portions of a robot for gripping the heat sink. The cap (10) is formed with notches (103) corresponding to the recessed portions (202) and exposing the recessed portions (202).

Description

Positioning Method for Projection Device and Display Element Assembly

[0001] The present disclosure relates to a positioning method for a projection device and a display element assembly.

[0002] Projection devices including a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element that modulate liquid crystal according to each of a red signal, a green signal, and a blue signal constituting a video signal are widespread (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2003-140103

[0004] Since the liquid crystal display element generates heat when irradiated with illumination light, a heat sink is attached to the liquid crystal display element. By blowing air onto the heat sink by a fan, the heat sink can be cooled and the temperature of the liquid crystal display element can be lowered. When the projection device is operating, the amount of heat generated is different in the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element. The green liquid crystal display element becomes the hottest, and the red liquid crystal display element becomes the coldest.

[0005] Since the amount of heat generated is different in the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, resulting in different temperatures, in principle, it is desirable to attach a heat sink with a cooling capacity corresponding to the temperature of each liquid crystal display element to each liquid crystal display element. However, if the projection device includes heat sinks for each individual liquid crystal display element, the cost will increase significantly. Therefore, a heat sink having the same shape and size is commonly used for the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element. At this time, a heat sink having a cooling capacity that can sufficiently cool the green liquid crystal display element, which becomes the hottest, is used.

[0006] As a result, the temperature of the red liquid crystal display element, which does not become as hot as the green liquid crystal display element, may become too low, and the color balance may be disrupted due to the temperature variation among the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, making it impossible to obtain a high-quality projected image.

[0007] One or more embodiments aim to provide a preferred configuration or method in a projection device in which a single heat sink having a single cooling capacity is used in common for a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element.

[0008] A first aspect of one or more embodiments provides a projection device comprising: a liquid crystal display element that modulates liquid crystal in accordance with a video signal; a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element; and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein one or more fins of the heat sink have at least two recesses formed therein for engaging with an engaging portion provided by a robot for the robot to grip the heat sink, and the cap has notches formed therein corresponding to each recess to expose each recess.

[0009] A second aspect of one or more embodiments provides a method for positioning a display element assembly, in which a cap is pre-placed over the heat sink of a display element assembly including a liquid crystal display element to which a heat sink is fixed, and fixed to the heat sink, and the display element assembly with the cap placed over the heat sink is positioned on a base.

[0010] A third aspect of one or more embodiments provides a projection device comprising: a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element that modulate the liquid crystal according to the red signal, green signal, and blue signal that constitute the video signal, respectively; a red heat sink, a green heat sink, and a blue heat sink fixed to the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, respectively, and having the same shape and size; and a cap placed over the red heat sink to reduce the cooling effect of the red heat sink on the red liquid crystal display element.

[0011] A fourth aspect of one or more embodiments provides a projection device comprising a liquid crystal display element that modulates liquid crystal in accordance with a video signal, a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element, and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein at least one opening is formed on the upper surface of the cap.

[0012] A fifth aspect of one or more embodiments provides a projection device comprising a liquid crystal display element that modulates liquid crystal in accordance with a video signal, a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element, and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein the cap has a plurality of protruding walls inserted between two adjacent fins of a plurality of fins on the heat sink.

[0013] According to one or more embodiments of the projection device and the positioning method for the display element assembly, a preferred configuration or method can be obtained for a projection device in which a single heat sink having a single cooling capacity is used in common for the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element.

[0014] Figure 1 is a perspective view showing a projection device according to the first embodiment. Figure 2 is a perspective view showing a display element assembly used in the projection devices according to the first to fourth embodiments. Figure 3 is a perspective view of the display element assembly used in the projection devices according to the first to fourth embodiments, viewed from the back side. Figure 4 is a perspective view showing the projection device according to the first embodiment with a cap placed over the red liquid crystal display element. Figure 5 is a perspective view showing the projection device according to the first embodiment with a duct attached. Figure 6 is an enlarged perspective view of the duct. Figure 7 is an enlarged perspective view showing the duct with the first and second blower fans connected. Figure 8 is an enlarged perspective view of the red heat sink. Figure 9 is a perspective view showing a cap of a comparative example. Figure 10 is an enlarged perspective view showing the red heat sink with a cap placed over it. Figure 11 is a perspective view showing a method for fixing a temperature measuring element to the display element assembly. Figure 12 is an enlarged perspective view showing a cap used in the projection device according to the second embodiment. Figure 13 is a perspective view showing a method for fixing the cap in the projection device according to the second embodiment. Figure 14 is an enlarged perspective view showing a cap used in the projection device according to the third embodiment. Figure 15 is an enlarged perspective view showing another cap used in the projection device according to the third embodiment. Figure 16 is an enlarged perspective view showing yet another cap used in the projection device according to the third embodiment. Figure 17 is an enlarged perspective view showing yet another cap used in the projection device according to the third embodiment. Figure 18 is a perspective view showing the projection device according to the fourth embodiment.

[0015] The projection devices according to the first to fourth embodiments will be described below with reference to the attached drawings.

[0016] <First Embodiment> The first embodiment aims to provide a projection device that can obtain high-quality projected images by using a single heat sink with a single cooling capacity in common for the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, as a preferred configuration for the projection device.

[0017] In Figure 1, the projection device 100 according to the first embodiment includes a red heat sink 2R, a green heat sink 2G, and a blue heat sink 2B within the housing 101 for cooling the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, respectively. The red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element are abbreviated as R display element, G display element, and B display element, respectively. The R display element, G display element, and B display element are reflective liquid crystal display elements.

[0018] The red heatsink 2R, the green heatsink 2G, and the blue heatsink 2B are abbreviated as R heatsink 2R, G heatsink 2G, and B heatsink 2B, respectively. The R heatsink 2R, G heatsink 2G, and B heatsink 2B are collectively referred to as heatsink 2. Heatsink 2 is made of aluminum. As will be described later, in the projection device 100 according to the first embodiment, a cap 10 (see Figure 4) is placed over the R heatsink 2R. In Figure 1, the R heatsink 2R is shown with the cap 10 removed.

[0019] As shown in the enlarged perspective views of Figures 2 and 3, heat sinks 2R for R, 2G for G, and 2B for B are fixed to the R display element 1R, G display element 1G, and B display element 1B, respectively. Flexible printed circuit boards 4R, 4G, and 4B, which connect to a main board (not shown), are connected to the R display element 1R, G display element 1G, and B display element 1B, respectively.

[0020] The heat sinks 2R, 2G, and 2B are equipped with temperature measuring elements 5R, 5G, and 5B, respectively, for measuring the temperatures of the R display element 1R, the G display element 1G, and the B display element 1B. The temperature measuring elements 5R, 5G, and 5B can be composed of thermistors. The temperature measuring elements 5R, 5G, and 5B are wired to the main board, but the wiring to the main board is not shown in the diagram.

[0021] The main board and flexible printed circuit boards 4R, 4G, and 4B modulate the liquid crystals in the liquid crystal layers of the R display element 1R, G display element 1G, and B display element 1B, respectively, according to the red, green, and blue signals that constitute the video signal. The red, green, and blue signals are abbreviated as R signal, G signal, and B signal, respectively.

[0022] The heatsinks 2R for R, 2G for G, and 2B for B have the same shape and size. Heatsink 2 is a heatsink that has sufficient cooling capacity to cool the G display element 1G, which generates the highest temperature. A single heatsink 2 with a single cooling capacity is used in common for the R display element 1R, the G display element 1G, and the B display element 1B.

[0023] The components including the R display element 1R, G display element 1G, and B display element 1B to which the heat sink 2 is fixed will be referred to as display element assemblies 1AR, 1AG, and 1AB, respectively. Here, the display element assemblies 1AR, 1AG, and 1AB also include flexible printed circuit boards 4R, 4G, and 4B, and metal members such as aluminum plates 3R, 3G, and 3B, respectively.

[0024] Returning to Figure 1, the display element assemblies 1AR, 1AG, and 1AB are fixed to the base 6 by metal members 3R, 3G, and 3B, and are positioned in the arrangement shown in Figure 1. Display element assemblies 1AR and 1AB are separated by a predetermined distance and face each other. Display element assembly 1AG is positioned in a direction perpendicular to the direction connecting display element assemblies 1AR and 1AB.

[0025] The red, green, and blue illumination lights generated based on the light emitted from the light source 7 are irradiated onto the R display element 1R, G display element 1G, and B display element 1B, respectively. The light source 7 includes, for example, a laser diode. The red, green, and blue illumination lights are modulated by the liquid crystal according to the R, G, and B signals, reflected by the reflective electrode, and emitted from the R display element 1R, G display element 1G, and B display element 1B. A composite prism (not shown) combines the modulated light emitted from the R display element 1R, G display element 1G, and B display element 1B and projects it onto the projection lens 9 inside the lens barrel 8. The projection lens 9 projects the combined light onto a screen (not shown).

[0026] The heatsinks 2R for R, 2G for G, and 2B for B are configured to be cooled by blowing air from a fan (described later) through a duct (described later). By cooling each heatsink 2, the temperatures of the R display element 1R, G display element 1G, and B display element 1B can be lowered. As described above, since the heatsink 2 has sufficient cooling capacity to cool the G display element 1G, which gets the highest temperature, the temperature of the R display element 1R may become too low.

[0027] Therefore, as shown in Figure 4, the heat sink 2R for R, which is fixed to the R display element 1R, is covered with a cap 10 that reduces the cooling effect of the heat sink 2R on the R display element 1R. The cap 10 is placed only on the heat sink 2R for R. The cap 10 is made of plastic resin or rubber.

[0028] Figure 5 shows the projection device 100 in the state shown in Figure 4 with the duct 23 attached. Figure 6 is an enlarged perspective view of the duct 23, and Figure 7 shows the duct 23 with the first blower fan 22a and the second blower fan 22b connected. As shown in Figure 5, the projection device 100 is equipped with intake fans 21a and 21b that are mounted facing the outside of the housing 101. The intake fans 21a and 21b draw outside air into the housing 101.

[0029] As shown in Figures 6 and 7, the duct 23 has a first duct 23a and a second duct 23b. As shown in Figures 5 and 7, the projection device 100 includes a first blower fan 22a and a second blower fan 22b that send air taken into the housing 101 by intake fans 21a and 21b to the first duct 23a and the second duct 23b, respectively. The first blower fan 22a is a blower fan for supplying air to the heat sink 2R for R, and the second blower fan 22b is a blower fan for supplying air to the heat sink 2G for G and the heat sink 2B for B. The first blower fan 22a and the second blower fan 22b are, for example, sirocco fans.

[0030] The first duct 23a directs the air blown by the first blower fan 22a to the heat sink 2R for R. The second duct 23b directs the air blown by the second blower fan 22b to the heat sink 2G for G and the heat sink 2B for B. As shown in Figures 6 and 7, the second duct 23b has, beyond the branching point 23b0, a first branch duct 23b1 that divides the air blown by the second blower fan 22b and directs the divided first air to the heat sink 2G for G, and a second branch duct 23b2 that directs the divided second air to the heat sink 2B for B. The portions of the first branch duct 23b1 and the second branch duct 23b2 in the second duct 23b are curved toward the heat sink 2G for G and the heat sink 2B for B.

[0031] Since the G display element 1G becomes hotter than the B display element 1B, it is preferable to make the cross-sectional area of ​​the first branch duct 23b1 wider than the cross-sectional area of ​​the second branch duct 23b2 so that the airflow rate of the first wind is greater than that of the second wind.

[0032] The heatsinks for G (2G) and B (2B) are positioned such that the heatsink for G (2G) is towards the back of the second blower fan (22b) and the heatsink for B (2B) is towards the front. The first branch duct (23b1) is positioned on the outside and the second branch duct (23b2) on the inside so that the distance from the branching point (23b0) in the second duct (23b) to the heatsink for G (2G) is long and the distance to the heatsink for B (2B) is short.

[0033] A curved duct has the property that the airflow is greater on the outside than on the inside. Therefore, the air blown by the second blower fan 22b flows more through the first branch duct 23b1, which is located on the outside of the curved first branch duct 23b1 and the second branch duct 23b2. As a result, the airflow of the first air that flows through the first branch duct 23b1 to the heat sink 2G for G is greater than the airflow of the second air that flows through the second branch duct 23b2 to the heat sink 2B for B. In addition to the fact that the cross-sectional area of ​​the first branch duct 23b1 is larger than that of the second branch duct 23b2, the first branch duct 23b1 is located on the outside of the curve, so the airflow of the first air can be made greater than that of the second air, thereby increasing the cooling capacity of the G display element 1G.

[0034] In the projection device 100 according to the first embodiment, let's assume that the cap 10 is not placed over the heat sink 2R for R. Since the R display element 1R is the least likely to heat up, the temperature of the R display element 1R may become too low, and the temperature variation between the R display element 1R, G display element 1G, and B display element 1B may disrupt the color balance, making it impossible to obtain a high-quality projected image. In the projection device 100 according to the first embodiment, since the cap 10 is placed over the heat sink 2R for R, the temperature of the R display element 1R does not become too low, making it possible to obtain a high-quality projected image.

[0035] In the projection device 100 according to the first embodiment, the duct 23 is composed of a first duct 23a and a second duct 23b. The first duct 23a guides the air blown by the first blower fan 22a to the heat sink 2R for R. The second duct 23b guides the air blown by the second blower fan 22b to the G display element 1G and the B display element 1B. With this configuration, when the temperature of the R display element 1R is too low compared to the temperatures of the G display element 1G and the B display element 1B, the airflow from the first blower fan 22a can be reduced or the first blower fan 22a can be stopped.

[0036] Therefore, according to the projection device 100 of the first embodiment, it is possible to appropriately control the temperatures of the R display element 1R, the G display element 1G, and the B display element 1B.

[0037] <Second Embodiment> The second embodiment aims to provide a preferred configuration for a cap that covers a heat sink and a preferred method for fixing the cap, as a preferred configuration for a projection device in which a single heat sink having a single cooling capacity is used in common for a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element.

[0038] The overall configuration of the projection device 100 according to the second embodiment is the same as that of the projection device 100 according to the first embodiment. In the projection device 100 according to the second embodiment, parts that are substantially the same as those in the projection device 100 according to the first embodiment are denoted by the same reference numerals, and their descriptions may be omitted. The projection device 100 according to the second embodiment is characterized by the configuration of the cap 10 and the method of fixing the cap 10.

[0039] A robot (not shown) grasps each heat sink 2 of the display element assemblies 1AR, 1AG, and 1AB and positions the display element assemblies 1AR, 1AG, and 1AB on the base 6 as shown in Figure 1. The positional accuracy of the R display element 1R, G display element 1G, and B display element 1B on the base 6 is important for obtaining high-quality projected images without registration misalignment of the R, G, and B signals. The robot accurately positions the R display element 1R, G display element 1G, and B display element 1B, to which the heat sink 2 is fixed, on the base 6, and the R display element 1R, G display element 1G, and B display element 1B are fixed on the base 6 with adhesive or the like.

[0040] As shown in the enlarged view of Figure 8, the heat sink 2R for R has recesses 202 formed therein, which serve as engaged parts for the engaging part of the robot to engage with when gripping the heat sink 2R for R. The recesses 202 are formed near the lower ends of the two outermost fins 201. The recesses 202 are formed in a total of four locations: on the front end faces of the two fins 201 and on the rear end faces of the two fins 201 that are not visible in Figure 8. The heat sink 2G for G and the heat sink 2B for B have the same configuration. It is sufficient that the recesses 202 are formed in at least two locations so that the robot can grip the heat sink 2.

[0041] The cap 10, which is placed over the heat sink 2R for R, needs to be fixed to the display element assembly 1AR so that it does not easily come off the heat sink 2R for R. One possible solution is to fix the cap 10' to the heat sink 2R for R by providing four claws 102 that engage with four recesses 202 on the heat sink 2R for R, as shown in Figure 9.

[0042] When the cap 10' is placed over the R-type heatsink 2R, the robot cannot grasp the R-type heatsink 2R. Therefore, the robot positions the display element assembly 1AR, which does not have the cap 10' placed over the R-type heatsink 2R, on the base 6, and then a person places the cap 10' over the R-type heatsink 2R. However, when done this way, the position of the display element assembly 1AR, which is precisely positioned on the base 6, shifts slightly, causing registration misalignment. For this reason, it is not preferable to use the cap 10' shown in Figure 9.

[0043] Therefore, as shown in the enlarged view of Figure 10, the cap 10 has notches 103 formed therein that expose each recess 202 corresponding to each recess 202. Because the cap 10 has notches 103 that expose each recess 202, the robot can grasp the heat sink 2R for R shown in Figure 10 with the cap 10 placed over it and position the display element assembly 1AR on the base 6. Thus, the position of the display element assembly 1AR, which is precisely positioned on the base 6, will not shift.

[0044] As shown in FIG. 11, a protruding portion 203 is formed at the lower end of the fin 201 on the most flexible printed circuit board 4R, 4G, 4B side of the heat sink 2. A through hole for passing the screw 31 is formed in the protruding portion 203. Protruding portions with through holes formed are formed at the ends of the temperature measurement elements 5R, 5G, 5B. The protruding portion 203 and the protruding portions at the ends of the temperature measurement elements 5R, 5G, 5B are overlapped, and the temperature measurement elements 5R, 5G, 5B and the heat sink 2 are fixed to the metal members 3R, 3G, 3B by the screws 31.

[0045] It is preferable to fix the cap 10 to the display element assembly 1AR as follows. As shown in FIG. 12, a protruding portion 104 is formed on the cap 10. A through hole 105 is formed in the protruding portion 104. As shown in FIG. 13, the protruding portion 203 of the heat sink 2R for R, the protruding portion at the end of the temperature measurement element 5R, and the protruding portion 104 of the cap 10 are overlapped, and the cap 10, the temperature measurement element 5R, and the heat sink 2R for R are fixed to the metal member 3R by the screw 31.

[0046] Thus, by clamping the protruding portion 104 of the cap 10 together with the protruding portion of the temperature measurement element 5R, there is no need to separately provide an independent configuration for fixing the cap 10 to the display element assembly 1AR, and the cap 10 can be fixed to the display element assembly 1AR.

[0047] As described above, in the projection device 100 according to the second embodiment, at least two recesses 202 are formed in one or more fins 201 of the heat sink 2 for engaging an engaging portion provided in the robot for the robot to grip the heat sink 2. In the cap 10, cutouts 103 are formed corresponding to the respective recesses 202 to expose the respective recesses 202. According to the projection device 100 according to the second embodiment, the robot is not prevented from gripping the heat sink 2.

[0048] The projection device 100 according to the second embodiment employs the following method for positioning the display element assembly 1AR. A liquid crystal display element (R display element 1R) to which a heat sink 2 (R heat sink 2R) is fixed is covered in advance with a cap 10 on the heat sink 2 of the display element assembly 1AR and fixed to a metal member 3R. The cap 10 reduces the effect of cooling the R display element 1R by the R heat sink 2R. The display element assembly 1AR with the cap 10 covering the heat sink 2 is positioned on the base 6.

[0049] According to such a positioning method, the positions of the R display element 1R, G display element 1G, and B display element 1B accurately positioned on the base 6 will not shift, so a high-quality projected image can be obtained.

[0050] <Third Embodiment> As a preferable configuration in a projection device in which a heat sink having a single cooling capacity is commonly used for a liquid crystal display element for red, a liquid crystal display element for green, and a liquid crystal display element for blue, the purpose is to provide a preferable configuration of a cap covering the heat sink.

[0051] The overall configuration of the projection device 100 according to the third embodiment is the same as that of the projection device 100 according to the first embodiment. In the projection device 100 according to the third embodiment, the same reference numerals are given to substantially the same parts as those in the projection device 100 according to the first embodiment, and the description thereof may be omitted. The projection device 100 according to the third embodiment is characterized by the configuration of the cap 10. The cap 10 in the third embodiment will be referred to as caps 10A to 10D.

[0052] As shown in FIG. 14, the cap 10A has, for example, a square opening 106 formed in the central portion of the upper surface. The shape of the opening is not limited to a square and may be other shapes such as a rectangle, a circle, an ellipse, etc. The position of the opening 106 is not limited to the central portion of the upper surface. Since the cap 10A has the opening 106 on the upper surface, the wind for cooling the R display element 1R enters the inside of the cap 10A from the opening 106. Therefore, the cap 10A can make the effect of reducing the action of cooling the R display element 1R weaker than that of the cap 10 without the opening 106.

[0053] If using a cap 10 without the opening 106 would excessively reduce the cooling effect of the heat sink 2R on the R display element 1R, then cap 10A can be used. Providing the opening 106 in the center of the upper surface reduces the effect of reducing the cooling effect of the R display element 1R compared to providing it at the edge of the upper surface.

[0054] As shown in Figure 15, the cap 10B has openings 107 formed at the four corners of its top surface. As shown in Figure 16, the cap 10C has an opening 106 in the center of its top surface and openings 107 formed at the four corners. The position and number of openings on the top surface of the cap 10 can be set as appropriate.

[0055] As shown in Figure 17, the cap 10D has notches 108 formed on the surface facing the end faces that form the thickness of each fin 201 of the heat sink 2, exposing the end faces of each fin 201. By forming notches 108 that expose the end faces of each fin 201, the air that cools the R display element 1R enters between each fin 201 through the notches 108, making it possible to significantly reduce the effect of reducing the cooling effect on the R display element 1R. By adjusting the height of the notches 108, the degree to which the effect of reducing the cooling effect on the R display element 1R is reduced can be adjusted.

[0056] In addition, the cap 10D has a plurality of protruding walls 109 that are inserted between two adjacent fins 201. The protruding walls 109 protrude downward from the inner upper end surface. If the cap 10D is made of an elastic material such as rubber, and the thickness of the protruding walls 109 is equal to the distance between two adjacent fins 201, the plurality of protruding walls 109 can be fitted between the plurality of fins 201, and the cap 10D can be fixed to the heat sink 2R for R.

[0057] If the cap 10D is fixed to the R-type heat sink 2R by fitting multiple protruding walls 109 between multiple fins 201, then it is not necessary to insert the screw 31 into the through hole 105 provided in the protruding part 104 and fasten the protruding part 104 together with the protruding part of the temperature measuring element 5R. Therefore, the cap 10D does not need to have a protruding part 104. Since the cap 10D can be fitted to the R-type heat sink 2R so that the multiple protruding walls 109 fit between the multiple fins 201, the step of fixing the cap 10D with the screw 31 can be eliminated.

[0058] The cap 10D shown in Figure 17 has an opening 106 in the center of its upper surface, but the opening 106 may be omitted. In the cap 10D, the protruding wall 109 may be omitted, and only notches 108 that expose the end faces of each fin 201 may be formed. In the cap 10D, the notches 108 may also be omitted. However, if the notches 108 are omitted, notches 103 that expose the recesses 202 formed in the heat sink 2R for R may be formed.

[0059] <Fourth Embodiment> The fourth embodiment aims to provide a projection device that can obtain high-quality projected images by using a single heat sink with a single cooling capacity in common for the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element.

[0060] The overall configuration of the projection device 100 according to the fourth embodiment is the same as that of the projection device 100 according to the first embodiment. In the projection device 100 according to the fourth embodiment, the same reference numerals are used for parts that are substantially the same as those in the projection device 100 according to the first embodiment, and their descriptions may be omitted. In the projection device 100 according to the fourth embodiment, the positions of the display element assemblies 1AR, 1AG, and 1AB are different from those in the projection device 100 according to the first embodiment.

[0061] The projection device 100 according to the fourth embodiment shown in Figure 18 omits the components shown in Figure 1 or Figure 5, such as the intake fans 21a and 21b, the first blower fan 22a, the second blower fan 22b, the duct 23, and the housing 101. As shown in Figure 18, various components such as the display element assemblies 1AR, 1AG, and 1AB are directly or indirectly arranged or connected on a single aluminum die-cast optical base 40.

[0062] In detail, the R display element 1R, G display element 1G, and B display element 1B, respectively, are fixed to the R heat sink 2R, G heat sink 2G, B heat sink 2B, light source 7, etc., which are arranged directly or indirectly on the horizontal base 401 of the optical base 40. The lens barrel 8 is passed through a circular opening formed in the vertical base 402 of the optical base 40 and is indirectly connected to the vertical base 402.

[0063] It is common practice to use separate aluminum die-casts for the optical base on which the R display element 1R, G display element 1G, and B display element 1B are arranged, and for the optical base on which the light source 7 is arranged. As in the fourth embodiment, costs can be reduced by arranging the R display element 1R, G display element 1G, B display element 1B, and light source 7 on a single aluminum die-cast optical base 40.

[0064] The optical base 40 has a large heat capacity on the side where the light source 7 is located, resulting in a high heat dissipation effect. Therefore, when the R display element 1R, G display element 1G, and B display element 1B are operating (i.e., when the projection device 100 is operating), the optical base 40 has a lower temperature on the R side and a higher temperature on the L side, as shown in Figure 18. Accordingly, in the projection device 100 according to the fourth embodiment, a heat sink 2G for G, to which the G display element 1G, which generates the most heat and reaches the highest temperature, is fixed, is placed at the lower temperature position on the optical base 40.

[0065] Specifically, on the optical base 40, among the heatsinks 2R for R, 2G for G, and 2B for B, the heatsink 2 to which the liquid crystal display element that generates the most heat when each liquid crystal display element is operating is fixed is positioned closer to the light source 7 than the heatsinks 2 to which the other liquid crystal display elements are fixed.

[0066] In Figure 18, the R heatsink 2R, to which the coldest R display element 1R is fixed, is positioned at a high temperature location on the optical base 40. To prevent an excessive temperature drop in the R display element 1R, the cap 10 may be placed only over the R heatsink 2R. Caps 10A to 10D may be used instead of cap 10.

[0067] According to the projection device 100 of the fourth embodiment, since the G display element 1G is positioned at a low temperature location on the optical base 40, temperature variations between the R display element 1R, the G display element 1G, and the B display element 1B are reduced, and a high-quality projected image can be obtained without disrupting the color balance.

[0068] The present invention is not limited to the first to fourth embodiments described above, and can be modified in various ways without departing from the spirit of the invention. The first to fourth embodiments can be combined in any combination of two or more embodiments. In the first to fourth embodiments, the caps 10, 10A to 10D are placed only on the heat sink 2R for R, but if the display element 1B becomes too cold, the caps 10, 10A to 10D may also be placed on the heat sink 2B for B. The caps 10, 10A to 10D may also be placed on at least one heat sink 2 other than the heat sink 2 to which the liquid crystal display element that generates the most heat is fixed.

[0069] This application claims priority based on Japanese Patent Applications No. 2024-190925, 2024-190927, 2024-190934, and 2024-190860, filed with the Japan Patent Office on 30 October 2024, all of which are incorporated herein by reference.

Claims

1. A projection device comprising: a liquid crystal display element that modulates liquid crystal in accordance with a video signal; a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element; and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein one or more fins of the heat sink have at least two recesses formed therein for engaging with an engaging portion provided by a robot for the robot to grip the heat sink, and the cap has notches formed therein corresponding to each recess to expose each recess.

2. The projection device according to claim 1, further comprising a temperature measuring element fixed to the heat sink by screws for measuring the temperature of the liquid crystal display element, wherein the cap is provided with a protrusion for fastening the cap to the heat sink together with the temperature measuring element by screws.

3. The projection device according to claim 1 or 2, wherein the liquid crystal display elements include a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element that modulate the liquid crystal according to the red signal, green signal, and blue signal that constitute the video signal, respectively, and the heat sinks include a red heat sink, a green heat sink, and a blue heat sink that are fixed to the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element respectively for cooling, and the heat sinks are the same shape and size as the heat sinks, and the cap is placed over the red heat sink to reduce the cooling effect of the red heat sink on the red liquid crystal display element.

4. A method for positioning a display element assembly, which includes a display element assembly with a heat sink to which a liquid crystal display element is fixed, wherein a cap is pre-placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element and fixed to the heat sink, and the display element assembly with the cap placed over the heat sink is positioned on a base.

5. A projection device comprising: a red liquid crystal display element, a green liquid crystal display element, and a blue liquid crystal display element that modulate the liquid crystal according to the red signal, green signal, and blue signal that constitute the video signal, respectively; a red heat sink, a green heat sink, and a blue heat sink fixed to the red liquid crystal display element, the green liquid crystal display element, and the blue liquid crystal display element, respectively, and having the same shape and size; and a cap placed over the red heat sink to reduce the cooling effect of the red heat sink on the red liquid crystal display element.

6. The projection device according to claim 5, further comprising: a first blower fan for supplying air to the red heatsink; a second blower fan for supplying air to the green heatsink and the blue heatsink; a first duct for guiding the air supplied by the first blower fan to the red heatsink; and a second duct for guiding the air supplied by the second blower fan to the green heatsink and the blue heatsink, wherein the second duct divides the air supplied by the second blower fan, and comprises a first branch duct for guiding the divided first air to the green heatsink, and a second branch duct for guiding the divided second air to the blue heatsink.

7. The projection device according to claim 6, wherein the cross-sectional area of ​​the first branch duct is wider than the cross-sectional area of ​​the second branch duct so that the airflow rate of the first wind is greater than the airflow rate of the second wind.

8. The projection device according to claim 6 or 7, wherein the green heat sink and the blue heat sink are arranged such that the green heat sink is on the rear side and the blue heat sink is on the front side with respect to the position of the second blower fan, and the first branch duct and the second branch duct in the second duct are arranged such that the first branch duct is on the outside and the second branch duct is on the inside, and they are curved toward the green heat sink and the blue heat sink, respectively.

9. A projection device comprising: a liquid crystal display element that modulates liquid crystal in accordance with a video signal; a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element; and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein at least one opening is formed on the upper surface of the cap.

10. The projection device according to claim 9, wherein an opening is formed in the center of the upper surface of the cap.

11. The projection device according to claim 9 or 10, wherein four openings are formed corresponding to the four corners of the upper surface of the cap.

12. A projection device comprising: a liquid crystal display element that modulates liquid crystal in accordance with a video signal; a heat sink fixed to the liquid crystal display element for cooling the liquid crystal display element; and a cap placed over the heat sink to reduce the cooling effect of the heat sink on the liquid crystal display element, wherein the cap has a plurality of protruding walls inserted between two adjacent fins of a plurality of fins on the heat sink.

13. The projection device according to claim 12, wherein a notch is formed on the surface of the cap that faces the end face forming the plate thickness of each fin in the plurality of fins, thereby exposing the end face of each fin.

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