Display device and head-up display device

Abstract

The present invention provides a display device with high-temperature protection measures and a head-up display device equipped with the display device. [Solution] The present invention provides a display device 10 comprising a liquid crystal display panel 11, a backlight unit 12 that illuminates the liquid crystal display panel 11 from the back, a case 13 that holds the liquid crystal display panel 11 and houses the backlight unit 12, and a fan 14 provided outside the case 13 for cooling the liquid crystal display panel 11 and the backlight unit 12, wherein the fan 14 is located to the side of the case 13, and the case 13 has a ventilation opening 13c in the area where the fan 14 is located.

Description

Technical Field

[0001] The present invention relates to a display device and a head-up display device including the display device.

Background Art

[0002] Conventionally, a head-up display device that displays a virtual image visible to a passenger (mainly a driver) by reflecting image light on a projection member such as a windshield of a vehicle is known. As a display device for a head-up display device, a device including a liquid crystal display panel and a lighting device that illuminates the liquid crystal display panel is known.

[0003] Since the display device of the head-up display device, particularly the liquid crystal display panel, becomes high in temperature, countermeasures against high temperature are required. As an example of the countermeasures against high temperature, a cooling method using a fan can be applied. Patent Document 1 discloses a display device including a liquid crystal display panel, a fan located on the side of the liquid crystal display panel and blowing air toward the liquid crystal display panel, and a lighting device that illuminates the liquid crystal display panel. In the display device disclosed in Patent Document 1, the air blown out from the fan flows separately to the front and back surfaces of the liquid crystal display panel, and by passing the air through both sides of the liquid crystal display panel, the cooling effect of the liquid crystal display panel by the fan can be enhanced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In display devices equipped with liquid crystal display panels and lighting devices, the lighting device, in addition to the liquid crystal display panel, can also become hot. In particular, head-up display devices require high-brightness displays to be visible even in outdoor sunlight, which increases the heat generated by the light source. Therefore, as a measure against high temperatures in the display device, it is necessary to cool the lighting device in addition to the liquid crystal display panel.

[0006] The present invention aims to provide a display device with high-temperature countermeasures and a head-up display device equipped with the display device. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides the following display device and head-up display device.

[0008] [1] LCD display panel and A backlight unit that illuminates the aforementioned liquid crystal display panel from the back, A case that holds the liquid crystal display panel and houses the backlight unit, A fan is provided on the outside of the case to cool the liquid crystal display panel and the backlight unit. A display device comprising, The aforementioned fan is located on the side of the case, A display device in which the case is provided with ventilation openings in the area where the fan is located. [2] The display device of [1], wherein a portion of the fan is positioned in front of the liquid crystal display panel in the direction from which the display light is emitted. [3] The display device according to [1] or [2], wherein the fan generates convection in opposite directions along the planar direction of the liquid crystal display panel on the front and back surfaces of the liquid crystal display panel. [4] A display device according to any of [1] to [3], wherein the fan is a blower-type fan. [5] The display device comprising an optical member in front of the liquid crystal display panel, any of the display devices described in [1] to [4]. A head-up display device equipped with one of the display devices described in [6][1] to [5]. [Effects of the Invention]

[0009] According to the present invention, a display device with high-temperature countermeasures and a head-up display device equipped with the display device are provided. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a vehicle equipped with a head-up display device according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of the head-up display device in the above embodiment. [Figure 3] This is a view of the display device in the above embodiment, as seen in the direction of arrow A in Figure 2. [Figure 4] This is a cross-sectional view showing the internal configuration of the display device in the above embodiment, as viewed in the direction of arrow A in Figure 2. [Figure 5] This is a view of the display device in the above embodiment, as seen in the direction of arrow B in Figure 3. [Figure 6] This figure shows a modified example of a display device. [Figure 7] This is a cross-sectional view showing a modified example of a display device. [Figure 8] This is a cross-sectional view showing a modified example of a display device. [Figure 9] This is a cross-sectional view showing a modified example of a display device. [Modes for carrying out the invention]

[0011] One embodiment of the present invention will be described below with reference to the drawings.

[0012] In the drawings, for the sake of easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed, and the detailed structure, some components (for example, the holding member, the circuit, the connecting means, and the fixing means), etc. are omitted. Also, in the drawings, for the sake of visibility, only some of the parts having the same attribute existing in plurality are provided with reference numerals, or the reference numerals attached in one drawing are omitted in other drawings.

[0013] In addition, in this specification, terms specifying shapes (for example, plate, square tube, L-shape, and rectangle), directions (for example, reverse direction), geometric conditions (for example, parallel), and their degrees (for example, uniform), etc. are not restricted to a strict meaning, and are interpreted including a range in which the same function can be expected. Also, in the following description, for the sake of easy understanding of the present disclosure, the description of well-known technical matters is appropriately omitted.

[0014] FIG. 1 is a schematic view of a vehicle equipped with a head-up display device 1 according to an embodiment of the present invention. FIG. 2 is a schematic view of the head-up display device 1 in the above embodiment. FIG. 3 is a view of the display device 10 in the above embodiment as seen in the direction of arrow A in FIG. 2. FIG. 4 is a cross-sectional view showing the internal configuration of the display device 10 in the above embodiment as seen in the direction of arrow A in FIG. 2. FIG. 5 is a view of the display device 10 in the above embodiment as seen in the direction of arrow B in FIG. 3. Note that the fan 14 is removed from the display device 10 in FIG. 5, and the arrangement position of the fan 14 is shown by a dotted line. FIG. 6 is a view showing a modification of the display device 10 in the above embodiment, and is a view of the display device 10 seen from the same direction as FIG. 5. Note that the fan 14 is the same as in FIG. 5. FIG. 7 is a cross-sectional view showing a modification of the display device 10, and is a view of the display device 10 seen from the same direction as FIG. 4. FIG. 8 is a cross-sectional view showing a modification of the display device 10, and is a view of the display device 10 seen from the same direction as FIG. 4. FIG. 9 is a cross-sectional view showing a modification of the display device 10, and is a view of the display device 10 seen from the same direction as FIG. 4.

[0015] As shown in FIG. 1, the head-up display device 1 is mounted within the dashboard of a vehicle. The head-up display device 1 displays a virtual image V visible to the vehicle occupants (mainly the driver) by reflecting image light on the windshield, which is an example of a projection member of the vehicle.

[0016] As shown in FIG. 2, the head-up display device 1 includes a display device 10, a first mirror 20, a second mirror 30, a control board (not shown), and a housing 40 that houses the first mirror 20, the second mirror 30, and the control board.

[0017] As shown in FIG. 2, the display device 10 is provided at the bottom of the housing 40 outside the housing 40, and is arranged such that the front surface of the liquid crystal display panel 11 of the display device 10 faces the internal space of the housing 40. The display device 10 displays an image under the control of a control board (not shown) and emits display light L representing the image toward the first mirror 20. In another embodiment, the display device 10 may be provided inside the housing 40. Details of the display device 10 will be described later.

[0018] The first mirror 20 reflects the display light L emitted by the display device 10 toward the second mirror 30. The first mirror 20 may be a plane mirror or a concave mirror. The first mirror 20 is held by the housing 40 by a holding member (not shown).

[0019] The second mirror 30 reflects the light reflected by the first mirror 20 toward the windshield. The second mirror 30 is a concave mirror, and the light reflected by the second mirror 30 allows the passenger to visually recognize an enlarged virtual image V. The second mirror 30 is rotatably held by the housing 40 via a stepping motor (not shown) and a holding member (not shown).

[0020] The control board is a printed circuit board (PCB) on which a wiring pattern is formed on an insulating plate-shaped substrate, such as glass epoxy resin (Glass Fiber Reinforced Plastics), and various electronic components such as a CPU (Central Processing Unit) are mounted, and controls the display device 10. The control board is connected to the display device 10 via a connection means not shown, such as a flexible flat cable (FPC). In addition to the FPC, a relay board may be interposed between the control board and the display device 10. The arrangement of the control board within the housing is not limited, but for example, the control board may be provided at the bottom inside the housing 40. In another embodiment, the control board may be provided outside the housing 40, or inside the display device 10. In the latter case, the control board may be integrated with the light source substrate 12a, which will be described later.

[0021] The housing 40 houses the first reflector 20, the second reflector 30, and the control board. The housing 40 comprises a housing body made of a non-transparent resin (e.g., polypropylene) or metal, and a window made of a translucent resin such as acrylic. The housing body has an upper opening to allow light reflected by the second reflector 30 to pass through. The window is provided in the upper opening of the housing body and ensures the waterproof and dustproof condition of the internal space of the housing 40 while allowing reflected light from the second reflector 30 to exit the housing 40.

[0022] The housing 40 holds the display device 10 at its bottom externally by fixing means (e.g., screws) not shown. The bottom of the housing 40 is provided with a bottom opening that opens along the outer edge of the display device 10 in order to allow the display light L emitted from the display device 10 to pass through. The display device 10 is positioned to cover the bottom opening to prevent external light, water droplets, dust, etc. from entering the inside of the housing 40 through the bottom opening.

[0023] The statement that the bottom opening "opens along the outer edge of the display device 10" includes cases where the bottom opening opens along the outer edge of the liquid crystal display panel 11 of the display device 10 toward the display surface of the display device 10, and cases where it opens along the outer edges of the liquid crystal display panel 11 and the fan 14 of the display device 10. In the latter case, a portion of the fan 14, that is, the portion of the fan 14 located in front of the front of the liquid crystal display panel 11 (to the left in Figure 3), may be located inside the housing 40. In the former case, the housing 40 may be provided with a notch or hole for allowing air blown out from the fan 14 of the display device 10 to pass through. The notch may be formed integrally and continuously with the bottom opening for allowing the display light L to pass through.

[0024] Next, the display device 10 will be described. As shown in Figures 3 and 4, the display device 10 comprises a liquid crystal display panel 11, a backlight unit 12, a case 13, and a fan 14 provided on the outside of the case 13.

[0025] The liquid crystal display panel 11 is a TFT (Thin Film Transistor) type liquid crystal display panel controlled by the control board described above. The liquid crystal display panel 11 receives light from the backlight unit 12 and emits display light L.

[0026] As shown in Figure 4, the backlight unit 12 is located on the back of the liquid crystal display panel 11 and illuminates the liquid crystal display panel 11. The backlight unit 12 comprises a light source substrate 12a, a plurality of light sources 12b, and an optical lens group. In this embodiment, the backlight unit 12 is a direct-lit backlight unit.

[0027] The light source substrate 12a is a PCB (Printed Circuit Board) with a wiring pattern formed on a plate-shaped substrate, such as an insulating plate-shaped substrate made of glass epoxy resin. Multiple light sources 12b are mounted on the light source substrate 12a, arranged in the vertical and horizontal directions when the light source substrate 12a is viewed from the front. Known light sources can be used as light sources 12b, for example, LEDs (Light-Emitting Diodes). Although not shown, a driver IC (Integrated Circuit) for driving the multiple light sources 12b is mounted on the light source substrate 12a. In another embodiment, the driver IC may be provided on the control board described above.

[0028] The optical lens group is not limited to, but for example, it consists of a condenser lens 12c, a lenticular lens 12d, and a field lens 12e, arranged in this order from the light source 12b side toward the liquid crystal display panel 11 side. That is, light emitted from the light source 12b passes through each lens in this order to illuminate the liquid crystal display panel 11. The condenser lens 12c focuses the light emitted from the light source 12b into parallel light with a nearly uniform light density. The lenticular lens 12d has multiple convex lenses and spreads the light that has passed through the condenser lens 12c in the vertical direction. The field lens 12e is a concave lens and spreads the light that has passed through the lenticular lens 12d and illuminates the liquid crystal display panel 11.

[0029] The case 13 holds the liquid crystal display panel 11 and also houses the backlight unit 12. The case 13 has a box-like shape with an opening on the side facing the liquid crystal display panel 11, and the liquid crystal display panel 11 is positioned to cover the opening of the case 13.

[0030] As shown in Figures 3 to 5, the case 13 consists of a holder 13a that holds the liquid crystal display panel 11 and a backlight unit box 13b connected to the rear of the holder 13a (opposite the liquid crystal display panel 11) and housing the backlight unit 12. The holder 13a and the backlight unit box 13b are fixed together by fastening means (e.g., screws) not shown. In another embodiment, the holder 13a and the backlight unit box 13b may not be separate parts, but a single component having both a part for holding the liquid crystal display panel 11 and a part for housing the backlight unit 12. The case 13 has a ventilation opening 13c at a position corresponding to the air intake of the fan 14, which will be described later.

[0031] The holder 13a is made of resin or metal and has a rectangular tubular shape with openings at the front and rear. The holder 13a holds the liquid crystal display panel 11, which is provided to cover the front opening, by fixing means (for example, screws) not shown. The field lens 12e, which covers the opening of the backlight unit box 13b, is located at the rear opening of the holder 13a.

[0032] The backlight unit box 13b has a bottomed rectangular tubular shape with an opening at the front. The backlight unit box 13b is made of a heat-conductive resin or metal.

[0033] The backlight unit box 13b houses the backlight unit 12, and a field lens 12e is provided so as to cover the opening of the backlight unit box 13b. The inner bottom surface of the backlight unit box 13b is in thermal contact with the light source substrate 12a. That is, the inner bottom surface of the backlight unit box 13b and the back surface of the light source substrate 12a may be in direct contact, or they may be indirectly in contact with each other through the interposition of a heat conductive member. Fins are provided on the back surface of the backlight unit box 13b to dissipate the heat generated by the light source substrate 12a and the light source 12b to the outside.

[0034] As shown in Figures 4 and 5, the ventilation opening 13c is provided in the case 13 at a position corresponding to the air intake of the fan 14, which will be described later. In this embodiment, the ventilation opening 13c is provided in the holder 13a, but is not limited to this, and may be provided at a position corresponding to the air intake or air outlet of the fan 14. For example, the ventilation opening 13c may be provided in the backlight unit box 13b. Alternatively, as shown in Figure 6, the ventilation opening 13c may be provided in both the holder 13a and the backlight unit box 13b (Figure 6a), or it may be provided so as to span both the holder 13a and the backlight unit box 13b (Figure 6b). From the viewpoint of efficiently cooling the liquid crystal display panel 11, it is preferable that the ventilation opening 13c is provided so that the forced convection generated by the fan 14 passes over the back of the liquid crystal display panel 11.

[0035] The fan 14 is positioned on the side of the case 13 and cools the liquid crystal display panel 11 and the backlight unit 12 by generating forced convection. The fan 14 comprises a fan body 14a that generates airflow by rotating an impeller with a motor, and a fan cover 14b that prevents water, dust, etc. from entering the head-up display device 1 and the display device 11. The fan body 14a is driven under the control of the aforementioned control board. A portion of the fan (a portion of the fan cover 14b) is positioned in front of the liquid crystal display panel 11 in the direction from which the display light L is emitted.

[0036] The fan body 14a is a blower-type fan. As shown in Figure 4, when driven, it draws in air from the front (main surface) of the fan body 14a, generating an airflow (air intake flow AFi), and blows air out toward the left side of Figure 4, generating an airflow (air outlet flow AFe).

[0037] The air intake flow AFi is an airflow from inside the holder 13a toward the fan body 14a via the vent 13c, and cools the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12 (the front of the field lens 12e) by generating forced convection inside the holder 13a. Specifically, the air intake flow AFi is a convection along the plane direction of the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12, and cools the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12 (the front of the field lens 12e) by expelling air heated by the heat from the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12 (the front of the field lens 12e) and by supplying fresh air to the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12 (the front of the field lens 12e).

[0038] The airflow AFe is generated by air being blown out laterally from the fan body 14a. The air blown out laterally from the fan body 14a is guided by the inner wall of the fan cover 14 in a direction aligned with the plane of the liquid crystal display panel 11. As a result, the airflow AFe is oriented along the plane of the liquid crystal display panel 11, cooling the front surface of the liquid crystal display panel 11. As shown in Figure 2, the front surface of the liquid crystal display panel 11 is located inside the housing 40 of the head-up display device 1, so the airflow AFe diffuses into the interior of the head-up display device 1.

[0039] In this embodiment, the inner wall of the fan cover 14 that guides the direction change of the air outlet flow AFe is L-shaped, but it is not limited as long as it can guide the direction change of the air outlet flow AFe, and may be curved, for example.

[0040] As described above, in this embodiment, the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12 (the front of the field lens 12e) are cooled by the air intake flow AFi, and the front of the liquid crystal display panel 11 is cooled by the air outlet flow AFe, which is a convection in the opposite direction to the air intake flow AFi. This allows for efficient cooling of the liquid crystal display panel 11 while simultaneously cooling the backlight unit 12.

[0041] The type and arrangement of the fan 14 can be changed as appropriate. For example, an example is shown in an embodiment in which both the holder 13a and the backlight unit box 13b are provided with ventilation openings 13c (see Figure 6a). As shown in Figure 7a, the fan body 14a is a fan that can blow air to both the left and right (for example, a centrifugal fan can be applied), and in addition to the cooling mechanism similar to that of the above embodiment, the airflow AFe from the air blown out to the right side of the fan body 14a cools the inside of the backlight unit box 13b and the backlight unit 12 (light source substrate 12a, multiple light sources 12b, condenser lens 12c and lenticular lens 12d). Alternatively, as shown in Figure 7b, the fan 14 may be configured to draw in air from both the holder 13a and the backlight unit box 13b through the ventilation openings 13c. In this case, the air intake flow AFi from inside the backlight unit box 13b towards the fan body 14a via the ventilation openings 13c cools the inside of the backlight unit box 13b and the backlight unit 12 (light source substrate 12a, multiple light sources 12b, condenser lens 12c, and lenticular lens 12d).

[0042] As shown in Figure 8, the display device 10 may include a member, such as an optical member 15, in front of the liquid crystal display panel 11 that can transmit light from the liquid crystal display panel 11. The optical member 15 is positioned so that the convection (airflow AFe) generated by the fan 14 passes through the space between the optical member 15 and the liquid crystal display panel 11. In other words, the optical member 15, together with the liquid crystal display panel 11, forms an air passage for the airflow AFe between the optical member 15 and the liquid crystal display panel 11. This allows the airflow AFe passing in front of the liquid crystal display panel 11 to efficiently cool the front surface of the liquid crystal display panel 11.

[0043] Furthermore, the display device 10 may include a ventilation passage connection that connects the ventilation passage for the air outlet flow AFe to the ventilation passage for the air intake flow AFi. The ventilation passage connection guides the air outlet flow AFe, which passes in front of the liquid crystal display panel 11, to the back of the liquid crystal display panel 11 and / or the front of the backlight unit 12. As shown in Figure 9, the ventilation passage connection may mainly consist of, for example, an airflow guide section provided outside the case 13 to guide the airflow and a through-hole provided in the case (Figure 9a), or it may mainly consist of an airflow guide section (not shown) provided in the ventilation passage for the air outlet flow AFe and a through-hole provided in the liquid crystal display panel 11 (Figure 9b).

[0044] The optical element 15 is, for example, a substantially rectangular plate-shaped member. The optical element 15 may be held by a holder 13a or by the liquid crystal display panel 11. A buffer member may be provided between the optical element 15 and the liquid crystal display panel 11 to prevent direct contact between the optical element 15 and the liquid crystal display panel 11. The optical element 15 may be a member having a specific function, such as a known hot mirror or diffuser plate, or it may simply be a member provided to form a ventilation passage for the air blown out flow AFe (for example, a plate-shaped member made of a translucent resin such as acrylic). The hot mirror is a mirror having a multilayer film that transmits light from the liquid crystal display panel 11 while reflecting (and absorbing) infrared rays. The diffuser plate diffuses the light emitted from the liquid crystal display panel 11.

[0045] It should be noted that the present invention is not limited by the embodiments and drawings described above, but is defined solely by the claims. Modifications (including the deletion of components) can be made as appropriate, without altering the essence of the invention. An example of a modification is described below.

[0046] In the above embodiment, the display device 10 is applied to a head-up display device 1, but is not limited to this and can be applied to various applications. For example, the display device 10 may be used as a display device that emits display light representing an image toward the windshield of a vehicle, for example, a ceramic forming part (for example, a so-called chromophore part) provided in the lower end region of the windshield of a vehicle.

[0047] In the above embodiment, the windshield was used as the projection target for the image light from the head-up display device 1, but the embodiment is not limited to this, and the projection target may be a dedicated combiner.

[0048] In the above embodiment, the head-up display device 1 is equipped with a first reflector 20 and a second reflector 30 as reflectors, but the type, number, arrangement, etc. of the reflectors are not limited. For example, the head-up display device 1 does not need to be equipped with the first reflector 20, in which case the arrangement of the display device 10 and the second reflector 30 can be adjusted as appropriate.

[0049] In the above embodiment, the liquid crystal display panel 11 is arranged substantially parallel to the light source substrate 12a, but is not limited thereto. For example, the liquid crystal display panel 11 may be inclined with respect to the left-right or up-down direction of the light source substrate 12a. [Explanation of Symbols]

[0050] 1. Head-up display device 10...Display device 11. LCD display panel 12. Backlight Unit 12a...Light source board 12b...Light source 12c...Condenser lens 12D...Lenticular lenses 12e... Field lens 13...cases 13a...Holder 13b...Backlight Unit Box 13c...Ventilation 14...fan 14a...Fan body 14b...Fan case 15. Optical Components 20...1st reflector 30...Second reflector 40... cabinet AFi... Air intake flow AFe... Air Outlet Flow L...Display light V...Illusion

Claims

1. LCD display panel, A backlight unit that illuminates the aforementioned liquid crystal display panel from the back, A case that holds the liquid crystal display panel and houses the backlight unit, A fan is provided on the outside of the case to cool the liquid crystal display panel and the backlight unit. A display device comprising, The aforementioned fan is located on the side of the case, A display device in which the case is provided with ventilation openings in the area where the fan is located.

2. The display device according to claim 1, wherein a portion of the fan is positioned in front of the liquid crystal display panel in the direction from which the display light is emitted.

3. The display device according to claim 1, wherein the fan generates convection in opposite directions along the planar direction of the liquid crystal display panel on the front and back surfaces of the liquid crystal display panel.

4. The display device according to claim 1, wherein the fan is a blower-type fan.

5. The display device includes an optical element in front of the liquid crystal display panel, The display device according to claim 1, wherein the optical member is provided such that the convection generated by the fan passes through the space between the optical member and the liquid crystal display panel.

6. A head-up display device comprising the display device described in any one of claims 1 to 5.

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