Display devices and head-up displays

Abstract

To provide a display device that can suppress a difference between temperature of a center part of a display area of a display panel and detection temperature of a temperature sensor to a small value.SOLUTION: A display device 20 comprises: a display panel 36 that has a display area 50 displaying an image on a front surface 36a and a peripheral area 52 which is arranged in an outside of the display area 50 and projects light incident on the rear surface 36b from the display area 50 as display light representing the image; a heat sink 32 that is arranged by facing the rear surface 36b of the display panel 36; a light transparent member 34 that is sandwiched between the display panel 36 and the heat sink 32; and a temperature sensor 38 that is arranged on the peripheral area 52 of the display panel 36, and detects temperature of the display panel 36. Seeing from a vertical direction for the front surface 36a of the display panel 36, the temperature sensor 38 is arranged at a position which does not overlap with at least one of the heat sink 32 and the light transparent member 34.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a display device and a head-up display.

Background Art

[0002] A head-up display (HUD) mounted on a vehicle is known. In this head-up display, light from a backlight enters the back of a display panel and exits from a display area on the front of the display panel. The light from the display area is reflected by a mirror and projected onto a vehicle windshield (front glass). As a result, a virtual image of an image displayed in the display area of the display panel is superimposed on the scenery in front of the vehicle on the vehicle windshield.

[0003] In the above-described head-up display, when sunlight enters the vehicle interior through the windshield from outside the vehicle and is reflected by the above-described mirror and condensed on the display area of the display panel, the display panel may become hot and be damaged. In order to avoid such a problem, the back of the display panel is brought into contact with a heat sink via a transparent member formed of glass, so that the heat of the display panel generated due to sunlight is conducted to the heat sink via the transparent member and dissipated. A technique has been proposed (see, for example, Patent Document 1).

[0004] Furthermore, a temperature sensor is disposed in a peripheral area outside the display area on the front surface of the display panel. When the temperature of the display panel detected by the temperature sensor exceeds a threshold value, a technique related to a so-called fail-safe function that thermally protects the display panel by displacing the above-described mirror has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In the conventional head-up displays described above, the heatsink has openings corresponding to the display area of ​​the display panel, and light from the backlight enters the back of the display panel through the openings in the heatsink. Therefore, in the display panel, heat is dissipated more easily by the heatsink in the peripheral area where the temperature sensor is located than in the central part of the display area. However, in such a configuration, the difference between the temperature in the central part of the display area of ​​the display panel and the temperature detected by the temperature sensor becomes large, which may cause the fail-safe function to not execute correctly.

[0007] Therefore, this disclosure provides a display device and a head-up display that can minimize the difference between the temperature in the center of the display area of ​​the display panel and the temperature detected by the temperature sensor. [Means for solving the problem]

[0008] A display device according to one aspect of the present disclosure is a display device used in a head-up display, comprising: a display panel having a display area for displaying an image on its front and a peripheral area disposed outside the display area, and projecting light incident on its back as display light representing the image from the display area; a heat sink disposed opposite to the back of the display panel; a light-transmitting member sandwiched between the display panel and the heat sink; and a temperature sensor disposed in the peripheral area of ​​the display panel for detecting the temperature of the display panel, wherein, when viewed from a direction perpendicular to the front of the display panel, the temperature sensor is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member.

[0009] These comprehensive or specific embodiments may be implemented as a system, method, integrated circuit, computer program, or recording medium such as a computer-readable CD-ROM (Compact Disc-Read Only Memory), or as any combination of a system, method, integrated circuit, computer program, and recording medium. [Effects of the Invention]

[0010] According to one aspect of this disclosure, the difference between the temperature in the center of the display area of ​​the display panel and the temperature detected by the temperature sensor can be kept small. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a vehicle equipped with a head-up display according to an embodiment. [Figure 2] This figure shows the area of ​​the windshield where the HUD image is displayed by the head-up display according to the embodiment. [Figure 3] This is a schematic diagram showing the configuration of a head-up display according to an embodiment. [Figure 4] This is a perspective view showing a display device according to an embodiment. [Figure 5] This is an exploded perspective view showing a display device according to an embodiment. [Figure 6] This is a plan view showing a display device according to an embodiment. [Figure 7] This is a bottom view showing a display device according to an embodiment. [Figure 8] This is a cross-sectional view of the display device according to the embodiment, shown along line VIII-VIII in Figure 6. [Figure 9] Figure 6 is a cross-sectional view of the display device according to the embodiment, along the line IX-IX. [Figure 10] This is a magnified view of the temperature sensor of the display device according to the embodiment. [Modes for carrying out the invention]

[0012] A display device according to a first aspect of the present disclosure is a display device used in a head-up display, comprising: a display panel having a display area for displaying an image on its front and a peripheral area disposed outside the display area, and projecting light incident on its back as display light representing the image from the display area; a heat sink disposed opposite to the back of the display panel; a light-transmitting member sandwiched between the display panel and the heat sink; and a temperature sensor disposed in the peripheral area of ​​the display panel for detecting the temperature of the display panel, wherein, when viewed from a direction perpendicular to the front of the display panel, the temperature sensor is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member.

[0013] According to this embodiment, when viewed from a direction perpendicular to the front of the display panel, the temperature sensor is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member. As a result, heat from the temperature sensor is less likely to be dissipated by the heat sink, and the difference between the temperature in the center of the display area of ​​the display panel and the temperature detected by the temperature sensor can be kept small. As a result, the temperature in the center of the display area of ​​the display panel can be estimated with high accuracy based on the temperature detected by the temperature sensor, and functions such as fail-safe functions can be executed correctly.

[0014] For example, in the display device according to the second embodiment, in the first embodiment, the display panel is constructed by stacking a plurality of optical members, and when viewed from a direction perpendicular to the front surface of the display panel, the predetermined area including the temperature sensor is an area that extends outward from the outermost shape of the temperature sensor by a thickness of at least one of the plurality of optical members, and is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member.

[0015] According to this aspect, when the optical member of the display panel is formed of an isotropic material, the heat of the temperature sensor spreads obliquely with respect to the vertical line inside the optical member. Even in such a case, the heat of the temperature sensor can be more effectively suppressed from being conducted to the heat sink through the light-transmitting member.

[0016] For example, in the display device according to the third aspect, in the first aspect or the second aspect, when viewed from a direction perpendicular to the front surface of the display panel, the peripheral region of the display panel may be configured to protrude outside the outer peripheral portion of the light-transmitting member.

[0017] According to this aspect, when viewed from a direction perpendicular to the front surface of the display panel, the temperature sensor can be arranged at a position that does not overlap with the light-transmitting member.

[0018] For example, in the display device according to the fourth aspect, in any one of the first aspect to the third aspect, when there is a highest temperature part on the front surface of the display panel where the temperature becomes the highest due to the condensing of sunlight from the outside, the distance between the highest temperature part and the temperature sensor may be configured to be longer than the distance between the center of the display area and the temperature sensor.

[0019] According to this aspect, when the distance between the highest temperature part and the temperature sensor is longer than the distance between the center of the display area and the temperature sensor, at the time of designing the display device, it is necessary to use the difference between the temperature of the highest temperature part and the detected temperature of the temperature sensor. Even in such a case, by adopting the configuration of the heat sink described above, the difference between the temperature of the highest temperature part and the detected temperature of the temperature sensor can be suppressed to be smaller.

[0020] For example, in the display device according to the fifth embodiment, in any one embodiment of the first to third embodiments, the display device further includes a light source that irradiates light onto the back surface of the display panel, and when there is a highest temperature area on the front surface of the display panel where the temperature is highest due to light from the light source irradiating the back surface of the display panel, the distance between the highest temperature area and the temperature sensor may be configured to be longer than the distance between the center of the display area and the temperature sensor.

[0021] According to this embodiment, when the distance between the highest temperature point and the temperature sensor is longer than the distance between the center of the display area and the temperature sensor, the difference between the temperature of the highest temperature point and the temperature detected by the temperature sensor must be used when designing the display device. Even in such cases, by adopting the heat sink configuration described above, the difference between the temperature of the highest temperature point and the temperature detected by the temperature sensor can be kept smaller.

[0022] For example, in the display device according to the sixth embodiment, in any one embodiment of the first to fifth embodiments, the heat sink may be formed in the shape of a frame having four sides, and the thickness of one of the four sides of the heat sink corresponding to the position of the temperature sensor may be configured to be thinner than the thickness of each of the other three sides.

[0023] According to this embodiment, it is possible to make it more difficult for the temperature sensor to dissipate heat more effectively.

[0024] For example, in the display device according to the seventh embodiment, in any one embodiment of the first to fifth embodiments, the heat sink may be formed in the shape of a frame having four sides, and the thermal conductivity of one of the four sides of the heat sink corresponding to the position of the temperature sensor may be configured to be lower than the thermal conductivity of each of the other three sides.

[0025] According to this embodiment, it is possible to make it more difficult for the temperature sensor to dissipate heat more effectively.

[0026] For example, in the display device according to the eighth embodiment, in any one embodiment of the first to fifth embodiments, the heat sink may be formed in the shape of a frame having four sides, and of the four sides of the heat sink, one side corresponding to the position of the temperature sensor is not anodized, while each of the other three sides is anodized.

[0027] According to this embodiment, it is possible to make it more difficult for the temperature sensor to dissipate heat more effectively.

[0028] For example, in the display device according to the ninth embodiment, in any one embodiment of the first to eighth embodiments, the display device may further be configured to include a heat dissipation sheet sandwiched between the heat sink and the light-transmitting member.

[0029] According to this embodiment, the heat conducted from the display panel to the light-transmitting member can be efficiently transferred to the heat sink via the heat dissipation sheet.

[0030] For example, in the display device according to the tenth embodiment, in the ninth embodiment, the heat sink may be formed in the shape of a frame having four sides, and the heat dissipation sheet may be sandwiched between each of the three sides of the heat sink other than the one side corresponding to the position of the temperature sensor and the light-transmitting member.

[0031] According to this embodiment, it is possible to make it more difficult for the temperature sensor to dissipate heat more effectively.

[0032] For example, in the display device according to the 11th embodiment, the thermal conductivity of the light-transmitting member may be configured to be 3 W / mK or less in any one embodiment of the first to tenth embodiments.

[0033] According to this embodiment, the heat conduction efficiency of the light-transmitting member can be more effectively increased.

[0034] For example, in the display device according to the 12th embodiment, the temperature sensor may be configured to be a thermistor in any one embodiment from the first to the 11th embodiment.

[0035] According to this embodiment, the temperature sensor can be miniaturized.

[0036] Furthermore, a head-up display according to a thirteenth aspect of this disclosure comprises a display device according to any one of the first to twelfth aspects, and a mirror that reflects display light projected from the display device toward a display medium.

[0037] According to this embodiment, as described above, the difference between the temperature in the center of the display area of ​​the display panel and the temperature detected by the temperature sensor can be kept small.

[0038] The embodiments will be described in detail below with reference to the drawings.

[0039] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit this disclosure. Furthermore, among the components in the following embodiments, those not described in the independent claim representing the highest-level concept will be described as optional components.

[0040] (Embodiment) [1. Head-Up Display Configuration] First, the configuration of the head-up display 2 according to the embodiment will be described with reference to Figures 1 to 3. Figure 1 is a diagram showing a vehicle 4 equipped with the head-up display 2 according to the embodiment. Figure 2 is a diagram showing the area 12 of the windshield 10 on which the HUD image 8 is displayed by the head-up display 2 according to the embodiment. Figure 3 is a schematic diagram showing the configuration of the head-up display 2 according to the embodiment.

[0041] As shown in Figure 1, the head-up display 2 according to this embodiment is located inside the dashboard 6 of a vehicle 4 such as an automobile. As shown in Figures 1 to 3, the head-up display 2 projects display light for displaying a virtual HUD image 8 toward, for example, the lower area 12 on the driver's side of the windshield 10 (an example of a display medium) of the vehicle 4, thereby reflecting the display light toward the driver 14 in the area 12 of the windshield 10. As a result, the driver 14 can see the virtual HUD image 8 superimposed on the view in front of the windshield 10 in the area 12 of the windshield 10. In other words, to the driver 14, the HUD image 8 appears as if it were displayed in the space 16 in front of the windshield 10.

[0042] As shown in Figure 3, the head-up display 2 comprises a main housing 18, a display device 20, a first mirror 22 (an example of a mirror), and a second mirror 24 (an example of a mirror).

[0043] The main housing 18 is box-shaped and made of a metal such as aluminum. The main housing 18 is located inside the dashboard 6 of the vehicle 4. Inside the main housing 18 are the display device 20, the first mirror 22, and the second mirror 24. The top surface of the main housing 18 is positioned opposite the windshield 10. An opening 26 is formed on the top surface of the main housing 18. This opening 26 is covered by a plate-shaped cover member 28 made of, for example, transparent resin.

[0044] The display device 20 is a PGU (Picture Generation Unit) that projects display light for displaying the HUD image 8 toward the first mirror 22. The configuration of the display device 20 will be described later.

[0045] The first mirror 22 is, for example, a convex mirror, and reflects the display light from the display device 20 toward the second mirror 24. The second mirror 24 is, for example, a concave mirror, and reflects the display light from the first mirror 22 toward the area 12 of the windshield 10. The display light from the second mirror 24 passes through the cover member 28, is reflected in the area 12 of the windshield 10, and then enters the eyes of the driver 14.

[0046] In this embodiment, the head-up display 2 is provided with two mirrors (a first mirror 22 and a second mirror 24), but it is not limited to this, and may be provided with one mirror or three or more mirrors.

[0047] [2. Display Device Configuration] Next, the configuration of the display device 20 according to the embodiment will be described with reference to Figures 3 to 10. Figure 4 is a perspective view showing the display device 20 according to the embodiment. Figure 5 is an exploded perspective view showing the display device 20 according to the embodiment. Figure 6 is a plan view showing the display device 20 according to the embodiment. Figure 7 is a bottom view showing the display device 20 according to the embodiment. Figure 8 is a cross-sectional view of the display device 20 according to the embodiment, taken along the line VIII-VIII in Figure 6. Figure 9 is a cross-sectional view of the display device 20 according to the embodiment, taken along the line IX-IX in Figure 6. Figure 10 is an enlarged view showing the temperature sensor 38 of the display device 20 according to the embodiment. Specifically, Figure 10(a) is an enlarged plan view showing the temperature sensor 38 of the display device 20 according to the embodiment, and Figure 10(b) is a cross-sectional view of the display panel 36 and the temperature sensor 38, taken along the line Xb-Xb in Figure 10(a).

[0048] In Figures 4 to 10, the horizontal direction of the display panel 36 is the X-axis direction, the vertical direction of the display panel 36 is the Y-axis direction, and the thickness direction of the display panel 36 is the Z-axis direction. Also, in Figures 4 to 10, the positive side of the Z-axis is "up", and the negative side of the Z-axis is "down".

[0049] As shown in Figures 3 to 9, the display device 20 comprises a PGU housing (not shown), a backlight 30 (an example of a light source) (see Figure 3), a heat sink 32, a light-transmitting member 34, a display panel 36, and a temperature sensor 38.

[0050] The PGU housing is fixed inside the main housing 18 (see Figure 3). The PGU housing is formed, for example, as a cylindrical shape with a rectangular cross-section and is mainly made of resin. Inside the PGU housing are a backlight 30, a heat sink 32, a light-transmitting member 34, a display panel 36, and a temperature sensor 38.

[0051] As shown in Figure 3, the backlight 30 is positioned opposite the opening 44 (described later) of the heatsink 32. The backlight 30 consists of a substrate 40 and LEDs (Light Emitting Diodes) 42 mounted on the substrate 40. For the sake of explanation, the backlight 30 is not shown in Figures 4 to 9.

[0052] The heat sink 32 is for dissipating heat generated by the display panel 36 and is made of a highly heat-dissipating metal such as aluminum. As shown in Figure 3, the heat sink 32 is positioned opposite the backlight 30. Also, as shown in Figures 8 and 9, the heat sink 32 is positioned opposite the back surface 36b of the display panel 36. As shown in Figures 5 to 7, the heat sink 32 is formed in a substantially rectangular frame shape having four sides 32a, 32b, 32c, and 32d, for example, in an XY planar view (i.e., viewed from a direction perpendicular to the front surface 36a of the display panel 36). A pair of sides 32a and 32c face each other, and a pair of sides 32b and 32d face each other.

[0053] As shown in Figures 5 and 7, the heat sink 32 has an opening 44 that corresponds to the display area 50 (described later) of the display panel 36. A portion of the lower surface of the light-transmitting member 34 (the surface on the heat sink 32 side) is exposed through the opening 44 of the heat sink 32, so that light from the LED 42 of the backlight 30 enters the back surface 36b of the display panel 36 through the opening 44 of the heat sink 32 and the light-transmitting member 34. In addition, a recess 46 is formed in the peripheral edge of the opening 44 in the area corresponding to the position of the temperature sensor 38, projecting radially outward from the opening 44.

[0054] The light-transmitting member 34 is made of a light-transmitting material, such as transparent glass, and is formed in the shape of a rectangular plate in an XY plane view. The light-transmitting member 34 is a member for conducting heat generated in the display panel 36 to the heat sink 32, and as shown in Figures 7 and 8, it is sandwiched between the back surface 36b of the display panel 36 and the peripheral edge of the opening 44 on the upper surface (the surface on the light-transmitting member 34 side) of the heat sink 32. That is, the upper surface (the surface on the display panel 36 side) of the light-transmitting member 34 is in heat-conductive contact with the back surface 36b of the display panel 36, and the lower surface of the light-transmitting member 34 is in heat-conductive contact with the peripheral edge of the opening 44 on the upper surface of the heat sink 32. The thermal conductivity of the light-transmitting member 34 is preferably 3 W / mK or less.

[0055] As shown in Figure 8, the size of the light-transmitting member 34 in the lateral direction (X-axis direction) is smaller than the size of the display panel 36 in the lateral direction. Also, as shown in Figure 9, the size of the light-transmitting member 34 in the vertical direction (Y-axis direction) is approximately the same as the size of the display panel 36 in the vertical direction. Note that the light-transmitting member 34 does not necessarily need to have 100% transparency; it may have a lower transparency (for example, a transparency of about 80-90%).

[0056] As shown in Figure 7, a heat dissipation sheet 48 is interposed between the lower surface of the light-transmitting member 34 and the peripheral edge of the opening 44 on the upper surface of the heat sink 32. Specifically, the heat dissipation sheet 48 is sandwiched between the lower surface of the light-transmitting member 34 and the portions of the peripheral edge of the opening 44 on the upper surface of the heat sink 32 that correspond to each of the three sides 32b, 32c, and 32d of the heat sink 32. As a result, the portion of the peripheral edge of the opening 44 on the upper surface of the heat sink 32 that corresponds to one side 32a of the heat sink 32 is in direct contact with the lower surface of the light-transmitting member 34. In addition, the portions of the peripheral edge of the opening 44 on the upper surface of the heat sink 32 that correspond to each of the three sides 32b, 32c, and 32d of the heat sink 32 are in contact with the lower surface of the light-transmitting member 34 via the heat dissipation sheet 48. The heat dissipation sheet 48 is a heat-conducting material with relatively high thermal conductivity and is mainly composed of a silicone resin sheet.

[0057] The display panel 36 is, for example, a liquid crystal display (LCD), and is formed in a rectangular plate shape in an XY planar view. The back surface 36b of the display panel 36 is positioned opposite the upper surface of the light-transmitting member 34 and is in thermally conductive contact with the upper surface of the light-transmitting member 34.

[0058] As shown in Figures 6 and 8, a display area 50 for displaying an image is formed on the front surface 36a of the display panel 36 (the surface opposite to the back surface 36b). The display area 50 has a rectangular shape in an XY planar view, and its size is smaller than the entire size of the front surface 36a of the display panel 36. Outside the display area 50 on the front surface 36a of the display panel 36, a peripheral area 52 is formed that does not contribute to the display of the image (i.e., light incident on the back surface 36b of the display panel 36 does not pass through this area). Wiring patterns and electrodes (not shown) are formed in the peripheral area 52. In this embodiment, the peripheral area 52 is arranged along one side 32a of the heat sink 32. The peripheral area 52 may also be formed in a frame-like shape that surrounds the entire circumference of the display area 50.

[0059] Here, the specific configuration of the display panel 36 will be described with reference to Figure 10(b). As shown in Figure 10(b), the display panel 36 is constructed by stacking, for example, a first polarizing plate 54, a first glass plate 56, a second glass plate 58, a second polarizing plate 60, and a diffuser plate 62 (an example of multiple optical components) in this order. The diffuser plate 62 is positioned on the side of the light-transmitting member 34, and the first polarizing plate 54 is positioned on the opposite side from the light-transmitting member 34. One end of the second glass plate 58 in the lateral direction (X-axis direction) protrudes laterally (to the positive side of the X-axis) than one end of the first polarizing plate 54, the first glass plate 56, and the second polarizing plate 60 in the lateral direction. That is, one end of the second glass plate 58 in the lateral direction protrudes laterally than one end of the light-transmitting member 34 in the lateral direction. Furthermore, the upper surface of one end of the second glass plate 58 that protrudes laterally defines the peripheral region 52 described above. As a result, the peripheral region 52 protrudes outward from the outer periphery of the light-transmitting member 34.

[0060] Light incident on the back surface 36b of the display panel 36 passes through the display panel 36 and is emitted from the display area 50. In other words, the display panel 36 projects the light that has passed through the display area 50 as display light representing the image displayed in the display area 50.

[0061] The temperature sensor 38 is a sensor for detecting the temperature of the display panel 36 and is composed of, for example, a thermistor. As shown in Figure 10(a), the temperature sensor 38 is formed in a rectangular shape with, for example, four sides in an XY plan view. As shown in Figures 6 to 8, the temperature sensor 38 is positioned in the peripheral area 52 of the display panel 36 and is located on the upper surface of one end of the second glass plate 58 in the lateral direction, which protrudes outward from the outer periphery of the light-transmitting member 34. Specifically, when viewed from a direction perpendicular to the front surface 36a of the display panel 36, the temperature sensor 38 is positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34.

[0062] In other words, when viewed from a direction perpendicular to the front surface 36a of the display panel 36, neither the heat sink 32 nor the light-transmitting member 34 is directly below the temperature sensor 38. This is because, as described above, a recess 46 is formed in the peripheral edge of the opening 44 of the heat sink 32 in the part corresponding to the position of the temperature sensor 38, and the peripheral area 52 of the display panel 36 corresponding to the position of the temperature sensor 38 protrudes outward beyond the outer periphery of the light-transmitting member 34.

[0063] [3. Effects] As shown in Figure 3, during the day, sunlight enters the vehicle interior from outside the vehicle 4 through the windshield 10. The sunlight that enters the vehicle interior enters the main housing 18 through the cover member 28 of the head-up display 2, and is reflected by the second mirror 24 and the first mirror 22, respectively, and enters the front surface 36a of the display panel 36 of the display device 20. As a result, the sunlight is concentrated on the front surface 36a of the display panel 36 of the display device 20, and heat is generated on the display panel 36 due to the sunlight.

[0064] Furthermore, when light from the backlight 30 shines on the back surface 36b of the display panel 36, heat is generated in the display panel 36 due to the light from the backlight 30.

[0065] In this way, the heat generated in the display panel 36 due to sunlight and / or light from the backlight 30 is conducted to the heat sink 32 via the light-transmitting member 34, and is dissipated into the atmosphere while diffusing inside the heat sink 32.

[0066] At this time, as described above, when viewed from a direction perpendicular to the front surface 36a of the display panel 36, the temperature sensor 38 is positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34. As a result, heat from the temperature sensor 38 is less likely to be conducted to the heat sink 32 via the light-transmitting member 34, and the difference between the temperature in the center of the display area 50 of the display panel 36 and the temperature detected by the temperature sensor 38 becomes smaller (for example, about 15 to 30°C).

[0067] Incidentally, the head-up display 2 includes a controller (not shown) that performs a fail-safe function to thermally protect the display panel 36 based on the temperature detected by the temperature sensor 38. The controller estimates a temperature that is a predetermined temperature (e.g., 25°C) higher than the temperature detected by the temperature sensor 38 as the temperature of the central part of the display area 50 of the display panel 36. Then, if the estimated temperature of the central part of the display area 50 exceeds a threshold (e.g., 103°C), the controller performs a fail-safe function, such as displacing at least one of the first mirror 22 and the second mirror 24, or reducing the luminous brightness of the LED 42 of the backlight 30.

[0068] Although not shown in the diagram, in the conventional head-up display described in the background technology section, the temperature sensor is positioned so as to overlap with both the heat sink and the light-transmitting member when viewed from a direction perpendicular to the front of the display panel. As a result, heat from the temperature sensor is easily conducted to the heat sink through the light-transmitting member, and the difference between the temperature in the center of the display area of ​​the display panel and the temperature detected by the temperature sensor becomes large (for example, around 50-60°C). However, when such a large temperature difference occurs, the frequency of fail-safe function activation increases, and the driver 14 is more likely to experience problems such as the HUD image 8 (virtual image) being dark or not being displayed at all.

[0069] In contrast, in the configuration of the head-up display 2 according to the embodiment, as described above, the heat from the temperature sensor 38 is less likely to be conducted to the heat sink 32 via the light-transmitting member 34, and the difference between the temperature in the center of the display area 50 of the display panel 36 and the temperature detected by the temperature sensor 38 becomes smaller. As a result, the temperature in the center of the display area 50 of the display panel 36 can be estimated with high accuracy, and the fail-safe function is executed correctly.

[0070] As shown in Figure 6, there may be a maximum temperature area 64 on the front surface 36a of the display panel 36, where the temperature is highest due to the concentration of sunlight from the outside (or due to light from the backlight 30 shining on the back surface 36b of the display panel 36). In such cases, for the following reasons, it is preferable that the distance D1 between the maximum temperature area 64 and the temperature sensor 38 is longer than the distance D2 between the center 66 of the display area 50 and the temperature sensor 38. Normally, the center 66 of the display area 50 is the highest temperature, so when designing the display device 20, the difference between the temperature of the center 66 and the temperature detected by the temperature sensor 38 is used. On the other hand, if the distance D1 between the maximum temperature area 64 and the temperature sensor 38 is longer than the distance D2 between the center 66 and the temperature sensor 38, when designing the display device 20, it is necessary to use the difference between the temperature of the maximum temperature area 64 and the temperature detected by the temperature sensor 38, rather than the difference between the temperature of the center 66 and the temperature detected by the temperature sensor 38. In such cases, by adopting the configuration of the heat sink 32 according to the embodiment, the difference between the temperature of the highest temperature part 64 and the temperature detected by the temperature sensor 38 can be kept smaller.

[0071] Furthermore, as shown in Figures 10(a) and (b), it is preferable that the predetermined region 68, including the temperature sensor 38, is positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34 when viewed from a direction perpendicular to the front surface 36a of the display panel 36. Here, the predetermined region 68 is the area that extends outward from each of the four sides (outermost dimensions) of the temperature sensor 38 by a distance equal to or greater than the thickness t (size in the Z-axis direction) of the second glass plate 58, when viewed from a direction perpendicular to the front surface 36a of the display panel 36. When the second glass plate 58 is made of an isotropic material, the heat from the temperature sensor 38 spreads within the second glass plate 58 at an angle of approximately 45° with respect to the vertical line (Z-axis direction). At this time, when viewed from a direction perpendicular to the front surface 36a of the display panel 36, the predetermined region 68, i.e., the range in which the heat from the temperature sensor 38 spreads, is positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34. This makes it possible to more effectively suppress the conduction of heat from the temperature sensor 38 to the heat sink 32 via the light-transmitting member 34.

[0072] (Other variations) Although a display device relating to one or more embodiments has been described above based on the above embodiments, this disclosure is not limited to the above embodiments. Without departing from the spirit of this disclosure, various modifications that a person skilled in the art can conceive of may be applied to the above embodiments, and forms constructed by combining components from different embodiments may also be included within the scope of one or more embodiments.

[0073] For example, in the above embodiment, the display light from the display device 20 was reflected by the area 12 of the windshield 10, but the invention is not limited to this, and the display light from the display device 20 may also be reflected by a combiner (an example of a display medium).

[0074] Furthermore, in the above embodiment, the temperature sensor 38 is positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34, but the invention is not limited to this, and the temperature sensor 38 may be positioned so as not to overlap with either the heat sink 32 or the light-transmitting member 34.

[0075] Furthermore, although the heat sink 32 is formed in a frame shape in the above embodiment, the thickness of one side 32a, which corresponds to the position of the temperature sensor 38, may be made thinner than the thicknesses of the other three sides 32b, 32c, and 32d. This makes it more difficult for the heat from the temperature sensor 38 to be dissipated effectively.

[0076] Alternatively, the thermal conductivity of one side 32a of the heat sink 32, which corresponds to the position of the temperature sensor 38, may be lower than the thermal conductivity of the other three sides 32b, 32c, and 32d. This configuration also makes it more difficult to dissipate heat from the temperature sensor 38.

[0077] Alternatively, of the four sides 32a, 32b, 32c, and 32d of the heat sink 32, the side 32a corresponding to the position of the temperature sensor 38 may not be anodized, while the other three sides 32b, 32c, and 32d may each be anodized. This configuration also makes it more difficult for the heat from the temperature sensor 38 to dissipate more effectively. [Industrial applicability]

[0078] The display device relating to this disclosure is applicable, for example, to a PGU (Programmable Unit) mounted in a head-up display for a vehicle. [Explanation of symbols]

[0079] 2 Head-Up Display 4 vehicles 6 Dashboard 8 HUD images 10 Windshield 12 areas 14. Driver 16 Space 18 Main Housing 20 Display device 22 The First Mirror 24 The Second Mirror 26,44 openings 28 Cover component 30 Backlight 32 Heatsinks 32a, 32b, 32c, 32d sides 34 Light-transmitting member 36 Display Panel 36a front 36b back 38 Temperature Sensor 40 circuit boards 42 LED 46 recess 48 Heat dissipation sheets 50 display area 52 Peripheral area 54. First polarizer 56 First glass plate 58. Second glass plate 60. Second polarizing plate 62 Diffuser 64 Highest temperature part 66 center 68. Predetermined area

Claims

1. A display device used in a head-up display, A display panel having a display area on the front for displaying an image and a peripheral area located outside the display area, and projecting light incident on the back as display light representing the image from the display area, A heatsink positioned opposite the rear of the display panel, A light-transmitting member sandwiched between the display panel and the heat sink, The display panel is equipped with a temperature sensor located in the peripheral area of ​​the display panel for detecting the temperature of the display panel, When viewed from a direction perpendicular to the front surface of the display panel, the temperature sensor is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member. Display device.

2. The aforementioned display panel is constructed by stacking multiple optical elements, When viewed from a direction perpendicular to the front surface of the display panel, the predetermined area including the temperature sensor is an area that extends outward from the outermost edge of the temperature sensor by a thickness greater than or equal to the thickness of one or more of the plurality of optical elements, and is positioned so as not to overlap with at least one of the heat sink and the light-transmitting member. The display device according to claim 1.

3. When viewed from a direction perpendicular to the front surface of the display panel, the peripheral region of the display panel extends outward beyond the outer periphery of the light-transmitting member. The display device according to claim 1.

4. If there is a point on the front surface of the display panel where the temperature is highest due to the concentration of sunlight from the outside, the distance between the point with the highest temperature and the temperature sensor is longer than the distance between the center of the display area and the temperature sensor. The display device according to claim 1.

5. The display device further includes a light source that illuminates the back surface of the display panel, If there is a point on the front of the display panel where the temperature is highest due to light from the light source irradiating the back of the display panel, then the distance between the point with the highest temperature and the temperature sensor is longer than the distance between the center of the display area and the temperature sensor. The display device according to claim 1.

6. The heat sink is formed in the shape of a frame having four sides, Of the four sides of the heat sink, the thickness of the side corresponding to the position of the temperature sensor is thinner than the thickness of each of the other three sides. The display device according to claim 1.

7. The heat sink is formed in the shape of a frame having four sides, Of the four sides of the heat sink, the thermal conductivity of the side corresponding to the position of the temperature sensor is lower than the thermal conductivity of each of the other three sides. The display device according to claim 1.

8. The heat sink is formed in the shape of a frame having four sides, Of the four sides of the heat sink, one side corresponding to the position of the temperature sensor is not anodized, while each of the other three sides is anodized. The display device according to claim 1.

9. The display device further comprises a heat dissipation sheet sandwiched between the heat sink and the light-transmitting member. The display device according to claim 1.

10. The heat sink is formed in the shape of a frame having four sides, The heat dissipation sheet is sandwiched between the light-transmitting member and each of the three sides of the heat sink other than the side corresponding to the position of the temperature sensor. The display device according to claim 9.

11. The thermal conductivity of the light-transmitting member is 3 W / mK or less. The display device according to claim 1.

12. The temperature sensor is a thermistor. The display device according to claim 1.

13. A display device according to any one of claims 1 to 12, The device comprises a mirror that reflects the display light projected from the display device toward a display medium. Head-up display.

Images