Liquid crystal display device

Abstract

A first flexible printed circuit board (2A) is valley-folded twice along a first side end surface of a heat sink (3) and is mountain-folded in a direction of 45 degrees. A first tip part (2A2) protrudes to the outside of the heat sink (3) from a third side end surface side sandwiched between the first side end surface and a second side end surface facing the first side end surface. A second flexible printed circuit board (2B) is valley-folded twice along the second side end surface of the heat sink (3) and is mountain-folded in a direction of 45 degrees. A second tip part (2B2) protrudes to the outside of the heat sink (3) from the third side end surface side.

Description

liquid crystal display device

[0001] The present disclosure relates to a liquid crystal display device.

[0002] A liquid crystal display device includes a liquid crystal display element that modulates illumination light in accordance with an image to be projected. In recent years, the number of pixels in images projected by liquid crystal display devices has been increasing. Liquid crystal display elements with a larger number of pixels, or so-called 8K, have appeared, with a horizontal pixel count of 7680 pixels and a vertical pixel count of 4320 pixels, than liquid crystal display elements with a horizontal pixel count of 3840 pixels and a vertical pixel count of 2160 pixels, or so-called 4K.

[0003] Japanese Patent Application Laid-Open No. 2022-139939

[0004] The number of connection terminals connected to each pixel electrode in a liquid crystal display element having 8K pixels is four times the number of connection terminals connected to each pixel electrode in a liquid crystal display element having 4K pixels. Therefore, it is difficult to form connection terminals for a liquid crystal display element having 8K pixels on only one side edge of the pixel electrode substrate. Therefore, as described in Patent Document 1, in a liquid crystal display element having 8K pixels, it is necessary to form connection terminals on two opposing side edges of the pixel electrode substrate.

[0005] When connection terminals are formed on two opposing side edges of the pixel electrode substrate, two drive substrates are required to drive the liquid crystal display element: a first drive substrate connected to the connection terminal formed on one side edge, and a second drive substrate connected to the connection terminal formed on the other side edge. Moreover, the two drive substrates are positioned at separate locations across the liquid crystal display element, which results in an increased size of the liquid crystal display device. Even for liquid crystal display devices equipped with liquid crystal display elements having a large number of pixels, such as 8K, it is desirable to reduce the size of the liquid crystal display device.

[0006] One or more embodiments aim to provide a liquid crystal display device that can be miniaturized while incorporating a liquid crystal display element having connection terminals formed on two opposing side ends of a pixel electrode substrate.

[0007] One aspect of one or more embodiments includes a reflective liquid crystal display element having first and second side edges facing each other and formed with connection terminals to connect to pixel electrodes in a plurality of pixels; first and second flexible printed circuit boards connected to the connection terminals formed on the first and second side edges and extending in opposite directions perpendicular to the end faces of the first and second side edges; and a heat sink to which the reflective liquid crystal display element is fixed with its light incident surface facing outward and which dissipates heat generated by the reflective liquid crystal display element, wherein the first flexible printed circuit board is folded twice along a first side edge face of the heat sink on the first side edge side, and a first tip end of the first flexible printed circuit board faces the first side edge face on the back side of the heat sink. and the second flexible printed circuit board is folded twice in a valley along the second side end face on the second side end side, so that the second tip of the second flexible printed circuit board is directed toward the first side end face on the back side of the heat sink, and is further folded in a mountain direction at 45 degrees with the first tip facing the second side end face, so that the first tip protrudes outside the heat sink from a third side end face side that is sandwiched between the first side end face and the second side end face.

[0008] According to one or more embodiments of the liquid crystal display device, the device can be made smaller while incorporating a liquid crystal display element having connection terminals formed on two opposing side edges of a pixel electrode substrate.

[0009] FIG. 1A is a front perspective view of a liquid crystal display element assembly included in a liquid crystal display device according to one or more embodiments. FIG. 1B is a rear perspective view of a liquid crystal display element assembly included in a liquid crystal display device according to one or more embodiments. FIG. 2 is an exploded perspective view of a liquid crystal display element assembly included in a liquid crystal display device according to one or more embodiments. FIG. 3 is a plan view showing a schematic configuration of a reflective liquid crystal display element included in the liquid crystal display element assembly. FIG. 4 is a plan view showing a state in which a reflective liquid crystal display element and a flexible printed circuit board are integrated together. FIG. 5 is a rear perspective view of a heat sink included in the liquid crystal display element assembly. FIG. 6 is a perspective view showing a bracket included in the liquid crystal display element assembly. FIG. 7 is a perspective view showing a state in which the bracket shown in FIG. 6 is fixed to a heat sink that fixes a reflective liquid crystal display element integrated with a flexible printed circuit board. FIG. 8A is a front plan view showing a state in which a reflective liquid crystal display element integrated with a flexible printed circuit board is fixed to a heat sink. FIG. 8B is a rear plan view showing a state in which a reflective liquid crystal display element integrated with a flexible printed circuit board is fixed to a heat sink. FIG. 9A is a plan view showing a state corresponding to FIG. 8B before the flexible printed circuit board is folded. FIG. 9B is a plan view showing a state in which one flexible printed circuit board is folded twice in a valley from the state shown in FIG. 9A. FIG. 9C is a plan view showing a state in which one flexible printed circuit board is folded twice in a mountain direction at 45 degrees from the state shown in FIG. 9B. FIG. 9D is a plan view showing a state in which the other flexible printed circuit board is folded twice in a valley from the state shown in FIG. 9C. FIG. 9E is a plan view showing a state in which the other flexible printed circuit board is folded twice in a mountain direction at 45 degrees from the state shown in FIG. 9D. FIG. 10A is a plan view showing a first preferred configuration example of a flexible printed circuit board. FIG. 10B is a plan view showing a second preferred configuration example of a flexible printed circuit board. FIG. 11 is a perspective view showing a state in which the flexible printed circuit board is folded from the state shown in FIG. 7 as shown in FIGS. 9A to 9E. FIG. 12 is a perspective view showing a state in which a pressing member for pressing the folded flexible printed circuit board is fixed to the heat sink in the state shown in FIG. 11.Fig. 13 is a perspective view showing a pressing member. Fig. 14 is a perspective view showing a drive substrate provided in the liquid crystal display element assembly. Fig. 15 is a perspective view showing a spacer provided in the liquid crystal display element assembly. Fig. 16 is a perspective view showing a state in which a fan is disposed near a heat sink in the liquid crystal display element assembly. Fig. 17 is a plan view showing the fan and liquid crystal display element assembly shown in Fig. 16 from the side with the bracket and spacer removed.

[0010] Hereinafter, a liquid crystal display device according to one or more embodiments will be described with reference to the accompanying drawings. The liquid crystal display device according to one or more embodiments includes a liquid crystal display element assembly 100 as shown in FIGS. 1A and 1B. FIG. 1A is a perspective view of the liquid crystal display element assembly 100 as seen from the front side, and FIG. 1B is a perspective view of the liquid crystal display element assembly 100 as seen from the rear side. The front side of the liquid crystal display element assembly 100 is the side on which a reflective liquid crystal display element (hereinafter referred to as a liquid crystal display element) 1 is located, and the rear side is the side opposite to the front side. If the liquid crystal display device includes three liquid crystal display elements 1 for red light, green light, and blue light, the liquid crystal display device includes three liquid crystal display element assemblies 100.

[0011] 2 is an exploded perspective view of the liquid crystal display element assembly 100. The liquid crystal display element assembly 100 includes a liquid crystal display element 1 (shown in FIG. 1A) to which flexible printed circuit boards 2A and 2B (first and second flexible printed circuit boards) are attached, a heat sink 3, a heater 4 (shown in FIG. 5), a bracket 5, a pressing member 6, a drive substrate 7A (first drive substrate), a drive substrate 7B (second drive substrate), and a spacer 8.

[0012] As shown in Fig. 3, the liquid crystal display element 1 includes a pixel electrode substrate 11 disposed on the bottom side and a glass substrate 12 disposed above the pixel electrode substrate 11. The pixel electrode substrate 11 is a silicon substrate. A plurality of pixels (not shown), for example, 8K pixels, and pixel electrodes (not shown) corresponding to each pixel are formed on the pixel electrode substrate 11. Transparent electrodes are formed on the glass substrate 12. A sealant 13 is provided between the pixel electrode substrate 11 and the glass substrate 12. Liquid crystal (not shown) is injected through an injection port 131 into the space surrounded by the sealant 13 between the pixel electrode substrate 11 and the glass substrate 12.

[0013] Side edges 11a and 11b (first and second side edges) on the long sides of the pixel electrode substrate 11 protrude beyond the side edge surfaces on the long sides of the glass substrate 12. Side edges 12a, 12b1, and 12b2 on the short sides of the glass substrate 12 protrude beyond the side edge surfaces on the short sides of the pixel electrode substrate 11. The side edges 12a, 12b1, and 12b2 are used to fix the liquid crystal display element 1 to the heat sink 3. A notch 12b3 between the side edges 12b1 and 12b2 is formed so that a sealant 132 can be injected into the injection port 131 using a dispenser nozzle (not shown). The injection port 131 is sealed with the sealant 132, and the liquid crystal is held in the space surrounded by the sealant 13 between the pixel electrode substrate 11 and the glass substrate 12.

[0014] Connection terminals 11t connected to each pixel electrode in a plurality of pixels are formed on the side edges 11a and 11b of the pixel electrode substrate 11. Since the connection terminals 11t are formed on both the side edges 11a and 11b, the liquid crystal display element 1 can be provided with connection terminals 11t corresponding to 8K pixels on the pixel electrode substrate 11. Both end portions on the short sides of the pixel electrode substrate 11 may be made to protrude beyond both end faces on the short sides of the glass substrate 12, and the connection terminals 11t may be formed on both end portions on the short sides. However, in a liquid crystal display element 1 having 8K or more pixels, it is preferable to form the connection terminals 11t on the side edges 11a and 11b on the long sides.

[0015] The surface of the liquid crystal display element 1 facing the glass substrate 12 is a light incident surface 14 onto which illumination light is incident. The illumination light incident on the liquid crystal display element 1 is modulated by the liquid crystal in accordance with the image to be projected, reflected by the liquid crystal or the reflective electrode formed on the pixel electrode substrate 11 side, and emitted from the light incident surface 14.

[0016] As shown in Figure 4, flexible printed circuit boards 2A and 2B are connected to connection terminals 11t at side ends 11a and 11b, respectively. The liquid crystal display element 1 and the flexible printed circuit boards 2A and 2B are integrated. The flexible printed circuit boards 2A and 2B supply the drive voltages and the like for each pixel electrode, which are supplied from drive substrates 7A and 7B, respectively, to the connection terminals 11t.

[0017] 5, a plurality of fins 31 are formed on the rear side of the heat sink 3 along the longitudinal direction of the rectangular heat sink 3. The heat sink 3 is made of, for example, aluminum. The plurality of fins 31 dissipate heat generated by the liquid crystal display element 1.

[0018] A heater housing section 32, where fins 31 are not formed, is formed in the center of the back side of the heat sink 3. A heater 4 serving as a heat source is housed in the heater housing section 32. A ceramic heater is preferably used as the heater 4. The heater 4 is held down by a presser plate 40 fixed to the heat sink 3 by a pair of screws 41, and is fixed so as not to fall out of the heater housing section 32. The presser plate 40 is formed, for example, by processing an aluminum plate. When the temperature of the liquid crystal display element 1 is low, the liquid crystal display element 1 is heated by the heater 4.

[0019] 5, the retainer plate 40 is actually fixed to the heat sink 3 by screws 41 with a fixing portion 51 (described later) of the bracket 5 positioned on the lower side. The retainer plate 40 has a pair of downward protruding pieces that elastically deform and press down on the heater 4.

[0020] As shown in Fig. 6, the bracket 5 has a fixing portion 51 for fixing to the heat sink 3 and a substrate mounting portion 52 for mounting the drive substrates 7A and 7B. The bracket 5 is integrally formed by processing, for example, an aluminum plate. As shown in Fig. 7, the bracket 5 is integrated with the heat sink 3 by fixing the fixing portion 51 to the rear surface of the heat sink 3 with four screws 53. The liquid crystal display element 1, to which the flexible printed circuit boards 2A and 2B are connected, is fixed to the heat sink 3. Fig. 7 shows that the presser plate 40 is fixed to the heat sink 3 with screws 41 via the fixing portion 51 located on the underside.

[0021] The liquid crystal display element 1, to which the flexible printed circuit boards 2A and 2B are connected, is fixed to a heat sink 3 as shown in Figures 8A and 8B. The liquid crystal display element 1 is fixed to the front of the heat sink 3 with the light incident surface 14 facing outward. Figure 8A shows the heat sink 3 to which the liquid crystal display element 1 is fixed, as viewed from the front, and Figure 8B shows the heat sink 3 as viewed from the back.

[0022] When the flexible printed circuit boards 2A and 2B are not bent, they extend in opposite directions perpendicular to the end faces of the side ends 11a and 11b. The flexible printed circuit boards 2A and 2B each have straight portions 2A1 and 2B1 having parallel side ends, and tip portions 2A2 and 2B2 (first and second tip portions) that branch into two distal ends of the straight portions 2A1 and 2B1. The flexible printed circuit boards 2A and 2B are bent multiple times as described below to reach the folded state shown in FIGS. 1A, 1B, and 2.

[0023] FIG. 9A corresponds to the state shown in FIG. 8B. In FIGS. 9A to 9E, the fins 31 of the heat sink 3 are omitted and only the outer shape is shown. The side end surface 33a (first side end surface) of the heat sink 3 is the side end surface on the side end portion 11a side of the pixel electrode substrate 11, and the side end surface 33b (second side end surface) opposite the side end surface 33a is the side end surface on the side end portion 11b side. The flexible printed circuit board 2A is folded twice at the bending points Fa1 and Fa2 shown in FIG. 9A, thereby being folded along the side end surface 33a as shown in FIG. 9B, and the tip portion 2A2 on the back side of the heat sink 3 is directed toward the side end surface 33b. The side end surface 33a is covered by the flexible printed circuit board 2A.

[0024] 9B, the flexible printed circuit board 2A is bent at a bending point Fa3 at a 45-degree angle relative to the side edge of the flexible printed circuit board 2A, with the tip portion 2A2 facing the side edge surface 33b. As a result, as shown in FIG. 9C, the tip portion 2A2 protrudes from a side edge surface 33c (third side edge surface) sandwiched between the side edge surfaces 33a and 33b to the outside of the heat sink 3.

[0025] Similarly, the flexible printed circuit board 2B is folded twice at the bending points Fb1 and Fb2 shown in Fig. 9C, and is thereby folded along the side end surface 33b as shown in Fig. 9D, with the leading end portion 2B2 facing the side end surface 33a on the rear surface side of the heat sink 3. The side end surface 33b is covered with the flexible printed circuit board 2B.

[0026] In Fig. 9D, the flexible printed circuit board 2B is bent at a bend point Fb3 at a 45-degree angle relative to the side edge of the flexible printed circuit board 2B, with the leading end portion 2B2 facing the side end surface 33a. As a result, as shown in Fig. 9E, the leading end portion 2B2 protrudes from the side end surface 33c to the outside of the heat sink 3. The flexible printed circuit boards 2A and 2B are overlapped over most of their surfaces. The leading end portions 2A2 and 2B2 protrude to the outside of the heat sink 3 at approximately the same position in the direction along the back surface of the heat sink 3, but are offset in the direction perpendicular to the back surface.

[0027] In the example shown in Figures 9A to 9E, flexible printed circuit board 2A is folded first, and then flexible printed circuit board 2B is folded, but flexible printed circuit board 2B may be folded first, and then flexible printed circuit board 2A may be folded.

[0028] Incidentally, flexible printed circuit boards 2A and 2B are coated with a shielding material to form a shielded structure, except for some areas such as connection terminals, which will be described later. The application of the shielding material can make it difficult to bend at bending points Fa1 to Fa3 and Fb1 to Fb3. To make it easier to bend flexible printed circuit boards 2A and 2B, flexible printed circuit boards 2A and 2B may be configured as shown in FIG. 10A or 10B.

[0029] 10A , bending grooves Ga1 and Ga2, where the shielding material is thin or no shielding material is applied, are provided on the back surface of flexible printed circuit board 2A at locations corresponding to bending locations Fa1 and Fa2. Bend groove Ga3, where the shielding material is thin or no shielding material is applied, is provided on the front surface of flexible printed circuit board 2A at a location corresponding to bending location Fa3. Bend grooves Ga1, Ga2, and Ga3 may have a predetermined width.

[0030] The rear surface of the flexible printed circuit board 2B has bending grooves Gb1 and Gb2 where the shielding material is thin or no shielding material is applied at locations corresponding to the bending locations Fb1 and Fb2. The front surface of the flexible printed circuit board 2B has bending groove Gb3 where the shielding material is thin or no shielding material is applied at a location corresponding to the bending location Fb3. The bending grooves Gb1, Gb2, and Gb3 may have a predetermined width.

[0031] When the flexible printed circuit boards 2A and 2B are bent at the bending points Fa1 and Fa2, Fb1 and Fb2, the flexible printed circuit boards 2A and 2B are bent at approximately 90 degrees at the bending points Fa1 and Fa2, Fb1 and Fb2. When the flexible printed circuit boards 2A and 2B are bent at the bending points Fa3 and Fb3, the flexible printed circuit boards 2A and 2B are bent at approximately 180 degrees. Therefore, the flexible printed circuit boards 2A and 2B coated with a shielding material are more difficult to bend when the flexible printed circuit boards 2A and 2B are bent at the bending points Fa3 and Fb3.

[0032] Therefore, only the bending grooves Ga3 and Gb3 may be provided on the front surfaces of the flexible printed circuit boards 2A and 2B.

[0033] 10B, rectangular bending regions Ha3 and Hb3, in which the shielding material is thin or not applied, may be provided on the front surface of the flexible printed circuit boards 2A and 2B so as to include bending points Fa3 and Fb3. Bending grooves Ga1, Ga2, Gb1, and Gb2 shown in FIG. 10A may or may not be provided on the rear surface of the flexible printed circuit boards 2A and 2B.

[0034] The rear surface of the flexible printed circuit board 2A may be provided with a rectangular bending region including bending points Fa1 and Fa2, where the shielding material is thin or no shielding material is applied.The rear surface of the flexible printed circuit board 2A may be provided with a rectangular bending region including bending points Fb1 and Fb2, where the shielding material is thin or no shielding material is applied.

[0035] In this way, by applying a thinner shielding material to the valley fold or mountain fold areas on the back or front of the flexible printed circuit boards 2A and 2B than to other areas, or by applying no shielding material at all, the flexible printed circuit boards 2A and 2B can be easily folded.

[0036] When the flexible printed circuit boards 2A and 2B are folded as described above, they change from the state shown in Fig. 7 to the state shown in Fig. 11. In Fig. 11, the flexible printed circuit boards 2A and 2B are shown folded back at approximately 180 degrees by two valley folds at approximately right angles and one mountain fold, but in reality, the flexible printed circuit boards 2A and 2B are folded gently so as not to damage them.

[0037] 12, a presser member 6 is fixed to the heat sink 3 so as to cover the folded flexible printed circuit boards 2A and 2B. Because the flexible printed circuit boards 2A and 2B are gently bent as described above, if the flexible printed circuit boards 2A and 2B are not covered by the presser member 6, the flexible printed circuit boards 2A and 2B will bulge away from the rear surface of the heat sink 3. Covering the flexible printed circuit boards 2A and 2B with the presser member 6 can prevent the flexible printed circuit boards 2A and 2B from bulging and interfering with other components.

[0038] It is preferable that the pressing member 6 gently presses down on the flexible printed circuit boards 2A and 2B. In order for the pressing member 6 to gently press down on the flexible printed circuit boards 2A and 2B, the pressing member 6 is configured as shown in FIG. 13. The pressing member 6 has a pair of pressing pieces 61 in the longitudinal direction of the heat sink 3 and an inclined pressing piece 62 that is connected to the middle of the pair of pressing pieces 61 and protrudes outward. The inclined pressing piece 62 is inclined so that its tip approaches the heat sink 3. The pressing member 6 is formed, for example, by processing an aluminum plate.

[0039] 13, there is a predetermined space between the pressing piece 61 and the tip of the inclined pressing piece 62 in a direction perpendicular to the back surface of the heat sink 3. Therefore, the pressing member 6 can gently press the flexible printed circuit boards 2A and 2B.

[0040] The pressing member 6 has a rectangular opening 63a at one end, and a locking piece 63 is formed on the distal side of the opening 63a. The pressing member 6 also has a connecting piece 64 at the other end that connects the pair of pressing pieces 61, with both ends of the connecting piece 64 being bent and having locking claws 641 formed at the ends. As shown in FIG. 12 , the locking piece 63 is locked to the end of the pressing plate 40 that presses down the heater 4. The locking claws 641 at both ends of the connecting piece 64 are locked to both side end surfaces of the fixing portion 51 of the bracket 5. In this way, the pressing member 6 is positioned with respect to the heat sink 3 and the bracket 5 by the locking piece 63 and the pair of locking claws 641, and presses down the flexible printed circuit boards 2A and 2B.

[0041] As shown in Fig. 14, the drive substrates 7A and 7B are provided with a pair of connectors 71 for connecting connection terminals provided at the very tip of the tip portion 2A2 or 2B2. The connectors 71 are provided at the ends of the drive substrates 7A and 7B. Four elongated openings 72 are formed at both side ends of the drive substrates 7A and 7B. The surface of the drive substrates 7A and 7B shown in Fig. 13 is the front surface.

[0042] 15 shows a spacer 8 disposed between the drive substrate 7A and the drive substrate 7B. The spacer 8 has protrusions 81 on both sides of one end. The spacer 8 is formed by processing an aluminum plate, for example.

[0043] The drive board 7A, spacer 8, and drive board 7B are mounted in this order on the board mounting portion 52 of the bracket 5 shown in Fig. 12. When the drive boards 7A and 7B are mounted on the board mounting portion 52, the surfaces of the drive boards 7A and 7B are parallel to the light incident surface 14. In Fig. 12, the drive board 7A is mounted with the end where the connector 71 is provided facing the heat sink 3 and the front surface facing downward. The drive board 7B is mounted with the end where the connector 71 is provided facing the heat sink 3 and the front surface facing upward. The connection terminals provided at the very ends of the tip portions 2A2 and 2B2 are connected to the connector 71.

[0044] When the drive substrate 7A, spacer 8, and drive substrate 7B mounted on the substrate mounting portion 52 are fastened with four screws 73 (shown in FIG. 2) inserted into the four openings 72, the liquid crystal display element assembly 100 shown in FIGS. 1A and 1B is formed. As shown in FIG. 1B, the pair of protrusions 81 come into contact with the tip surface 521 of the substrate mounting portion 52, so that the position of the spacer 8 in the direction toward the heat sink 3 is restricted.

[0045] If the drive substrates 7A and 7B are movable in directions toward or away from the heat sink 3, it is easy to connect the connection terminals to the connector 71. Because the openings 42 are elongated holes, before the drive substrate 7A, spacer 8, and drive substrate 7B are fixed to the substrate mounting portion 52 with the screws 73, the drive substrates 7A and 7B can be moved a predetermined distance toward or away from the heat sink 3. This makes it easy to connect the connection terminals to the connector 71. After the connection terminals are connected to the connector 71, the drive substrate 7A, spacer 8, and drive substrate 7B are completely fixed to the substrate mounting portion 52 with the screws 73.

[0046] In this manner, the liquid crystal display element assembly 100 shown in Figures 1A and 1B is constructed. The heat sink 3 to which the liquid crystal display element 1 is fixed is accurately positioned and fixed at a predetermined location within the housing of the liquid crystal display device. The liquid crystal display device may also include a main drive substrate other than the drive substrates 7A and 7B. The main drive substrate and the drive substrates 7A and 7B are connected to each other by a connecting cable. When the liquid crystal display device includes a main drive substrate, the main drive substrate drives the liquid crystal display element 1 via the drive substrates 7A and 7B. The drive substrates 7A and 7B function as relay substrates that drive the liquid crystal display element 1.

[0047] 16 , a fan 9 that blows air between the fins 31 of the heat sink 3 is disposed at a position a predetermined distance away from a side end surface 33d (fourth side end surface) that faces the side end surface 33c of the heat sink 3 in the liquid crystal display element assembly 100. When the fan 9 is rotated, the air generated by the fan 9 flows between the fins 31 and cools the heat sink 3. The air flowing between the fins 31 escapes from the side end surface 33c to the outside of the heat sink 3 and flows in the direction of the drive substrates 7A and 7B.

[0048] By folding the flexible printed circuit boards 2A and 2B as described above, the side end faces 33a and 33b of the heat sink 3 are covered by the flexible printed circuit boards 2A and 2B, respectively. Furthermore, the tip ends 2A2 and 2B2 of the flexible printed circuit boards 2A and 2B protrude from the side end face 33c toward the outside of the heat sink 3. The heat sink 3 has a plurality of fins 31 formed in a direction along the side end faces 33a and 33b, enabling efficient cooling of the heat sink 3 (liquid crystal display element 1). By setting the relationship between the folding method of the flexible printed circuit boards 2A and 2B and the direction of the fins 31 of the heat sink 3 in this manner, not only is the device more compact, but the liquid crystal display element 1 can also be efficiently cooled.

[0049] Figure 17 shows the fan 9 and liquid crystal display element assembly 100 shown in Figure 16 from the side, with the bracket 5 and spacer 8 removed. As shown in Figure 7, the fixing portion 51 of the bracket 5 is fixed to the rear surface of the heat sink 3, and the substrate mounting portion 52 is positioned displaced toward the rear surface. Therefore, as shown in Figure 17, the end surface of the drive substrate 7B, of the drive substrates 7A and 7B, does not face the side end surface 33c. The drive substrate 7B is positioned at a distance from the heat sink 3 in a direction perpendicular to the light incident surface 14.

[0050] The end face of the drive substrate 7A faces the side end face 33c. The substrate mounting portion 52 may be configured so that the end face of the drive substrate 7A does not face the side end face 33c. It is preferable that the end face of at least one of the drive substrates 7A and 7B does not face the side end face 33c and is positioned at a distance from the heat sink 3 in a direction perpendicular to the light incident surface 14.

[0051] Since neither of the drive substrates 7A nor 7B faces the side end surface 33c, the air generated by the fan 9 and passing from the side end surface 33c to the outside of the heat sink 3 flows almost unobstructed by the drive substrates 7A and 7B, thereby enabling efficient cooling of the heat sink 3 (liquid crystal display element 1).

[0052] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

[0053] This application claims priority based on Japanese Patent Application No. 2024-023716 filed with the Japan Patent Office on February 20, 2024, and Japanese Patent Application No. 2024-023719 filed with the Japan Patent Office on February 20, 2024, the entire disclosures of which are incorporated herein by reference.

Claims

1. A reflective liquid crystal display element having connection terminals formed on first and second side edges facing each other with respect to pixel electrodes of a plurality of pixels; first and second flexible printed circuit boards connected to the connection terminals formed on the first and second side edges and extending in opposite directions perpendicular to the edge faces of the first and second side edges; and a heat sink to which the reflective liquid crystal display element is fixed with its light incident surface facing outward, and which dissipates heat generated by the reflective liquid crystal display element, wherein the first flexible printed circuit board is folded twice in a valley along a first side edge face of the heat sink on the first side edge side, so that a first tip end of the first flexible printed circuit board on the back side of the heat sink is directed toward a second side edge face of the heat sink that faces the first side edge face, a second flexible printed circuit board that is folded twice along the second side end face on the second side end side so that a second tip of the second flexible printed circuit board faces the first side end face on the back side of the heat sink; and a second flexible printed circuit board that is folded twice along the second side end face on the second side end side so that a second tip of the second flexible printed circuit board faces the first side end face on the back side of the heat sink; and a second flexible printed circuit board that is folded twice along the second side end face on the second side end side so that a second tip of the second flexible printed circuit board faces the first side end face on the back side of the heat sink; and a second flexible printed circuit board that is folded twice along the second side end face on the second side end side so that a second tip of the second flexible printed circuit board faces the first side end face on the back side of the heat sink; and a second flexible printed circuit board that is folded 2. The liquid crystal display device according to claim 1, wherein the reflective liquid crystal display element has a rectangular shape, the first and second side edges are the side edges on the long sides of the reflective liquid crystal display element, and the heat sink has a rectangular shape, and the third side edge is the side edge on the short side of the heat sink.

3. A liquid crystal display device as described in claim 1 or 2, wherein the valley or mountain folds on the rear or front of the first and second flexible printed circuit boards are coated with a thinner shielding material than other areas or are not coated with any shielding material.

4. A liquid crystal display device according to claim 1 or 2, wherein the first and second flexible printed circuit boards are superimposed on each other, and further comprising a pressing member for pressing the first and second flexible printed circuit boards.

5. A liquid crystal display device as described in claim 1 or 2, further comprising first and second drive substrates arranged outside the third side end face and parallel to the light incident surface, and wherein connection terminals provided at the very ends of the first and second tip portions are connected to connectors provided on the first and second drive substrates, respectively.

6. A liquid crystal display device according to claim 1 or 2, wherein the heat sink has a plurality of fins formed in a direction along the first and second side end faces.

7. A liquid crystal display device as claimed in any one of claims 1 to 6, further comprising a bracket fixed to the heat sink, the bracket having board mounting portions for mounting the first and second drive boards outside the third side end face of the heat sink so that the faces of the first and second drive boards are parallel to the light incident surface, the first and second drive boards being mounted on the board mounting portions, and connection terminals provided at the very ends of the first and second end portions being connected to connectors provided on the first and second drive boards, respectively.

8. A liquid crystal display device as described in claim 7, wherein, before the first and second drive substrates are fixed to the substrate mounting portion, the first and second drive substrates mounted on the substrate mounting portion are configured to be freely movable a predetermined distance in a direction approaching the third side end surface and moving away from the third side end surface.

9. A liquid crystal display device as described in any one of claims 6 to 8, wherein the end face of at least one of the first and second drive substrates does not face the third side end face of the heat sink, and the at least one drive substrate is positioned at a distance from the heat sink in a direction perpendicular to the light incident surface.

10. The liquid crystal display device according to claim 6, further comprising a fan for blowing air between the plurality of fins, on a fourth side edge surface of the heat sink opposite the third side edge surface.

Images