JP2018087775A - Display device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device for a vehicle which suppresses occurrence of abnormality in display due to temperature rise of a display member.SOLUTION: The display device for a vehicle comprises a tabular display member 21 emitting display light L, a tabular transparent member 22 adhered to the display surface of the display member 21 by transparent adhesive 24, and a metal frame body 25 along the side surface of the transparent member 22. The frame body 25 is provided on the side of a side surface 22c with the exception of an incidence surface 22a and an emission surface 22b, through which the display light L mainly passes, in the transparent member 22.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle display device.

  Conventionally, a display device has been provided with heat radiating means for suppressing temperature rise from the viewpoint of maintaining a suitable display. For example, the display device described in Patent Literature 1 includes a liquid crystal panel, a heat conducting member that surrounds the liquid crystal panel so as to hold the liquid crystal panel, and a heat pipe that passes through the inside of the heat conducting member. The heat of the liquid crystal panel is transmitted to the heat conducting member, and the heat is radiated by the refrigerant (for example, water) circulating in the heat pipe. The heat pipe can efficiently dissipate the liquid crystal panel as the temperature difference between the liquid crystal panel and the heat pipe increases.

  Further, for example, the display device described in Patent Document 2 is positioned on the surface of a liquid crystal panel, for example, a transparent member made of sapphire or quartz (quartz), a holding frame that holds the liquid crystal panel, and is fixed to the holding frame. And a heat dissipating fin connected to the fixing member. The heat of the liquid crystal panel can be radiated from the transparent member to the radiating fin through the fixing member.

JP 2008-89721 A JP 2005-134858 A

  In the configuration of Patent Document 1, the heat pipe can effectively dissipate heat from the liquid crystal panel after the temperature difference between the liquid crystal panel and the heat pipe is increased by reducing the temperature of the refrigerant. For this reason, in the heat pipe, the timing at which heat radiation is effectively started is delayed. Similarly, also in the configuration of Patent Document 2, the heat dissipating fin can effectively dissipate the liquid crystal panel after the temperature difference between the liquid crystal panel and the heat dissipating fin becomes large. For this reason, the timing at which heat radiation is effectively started is delayed even in the heat radiation fin.

  Furthermore, for example, when the display device is mounted on a vehicle, the temperature difference between the ambient temperature and the heat-resistant temperature of the liquid crystal panel is small in a situation where the ambient temperature of the display device such as the passenger compartment is high. Specifically, when the atmospheric temperature in the passenger compartment rises to 85 ° C., the Bonanza generation temperature, which is the heat resistance temperature of the liquid crystal element in the liquid crystal panel, is about 105 ° C., and the heat resistance temperature of the polarizing plate of the liquid crystal panel is 95 ° C. Therefore, the temperature difference is about 20 ° C to 30 ° C. In this situation, sunlight is condensed in the vicinity of the liquid crystal panel, or light from the light source is irradiated on the liquid crystal panel, so that the heat pipe or the heat radiating fin cannot function effectively, and the temperature is 20 ° C. to 30 ° C. If the temperature rises above 0 ° C., the temperature of the liquid crystal panel exceeds the heat resistance temperature of the liquid crystal panel, and there is a risk that the display of the liquid crystal panel will be abnormal.

  An object of the present invention is to provide a display device for a vehicle that pays attention to the above-described problem and suppresses the occurrence of an abnormality in display as the temperature of the display member increases.

In order to achieve the above object, a vehicle display device according to the present invention includes:
A plate-like display member that emits display light;
A plate-like transparent member bonded to the display surface of the display member via a transparent adhesive;
A frame body made of a metal material is provided along the side surface of the transparent member.

Moreover, it is provided with the heat conductive member filled between the said frame and the side surface of the said transparent member, It is characterized by the above-mentioned.

Further, the frame body is bonded to the display member using the transparent adhesive.

Further, the frame body is provided on a side surface other than the incident surface and the light exit surface through which the display light in the transparent member mainly passes.

The display light is used as projection light for a head-up display.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that abnormality arises in a display with the temperature rise of a display member.

The schematic diagram of the vehicle carrying the head-up display apparatus which concerns on embodiment of this invention. Schematic which shows the structure of the head-up display apparatus which concerns on embodiment of this invention. Sectional drawing of the display unit which concerns on embodiment of this invention. The graph which shows the temperature change of the display member which concerns on embodiment of this invention. Sectional drawing which shows another example of the display unit of embodiment same as the above.

  Hereinafter, an embodiment in which a vehicle display device according to the present invention is mounted on a head-up display device will be described with reference to the accompanying drawings.

As shown in FIG. 1, the head-up display device 100 is mounted on the dashboard of the vehicle 2. The head-up display device 100 projects display light L onto a windshield (windshield) 3 that is an example of a projection member in the vehicle 2. The driver (viewer) 5 receives the display light L reflected on the windshield 3 as projection light, and can visually recognize the virtual image V superimposed on the real scene seen through the windshield 3.
(Configuration of head-up display device)

  As shown in FIG. 2, the head-up display device 100 includes a display unit (vehicle display device) 20, a light source unit 30, a plane mirror 60, a concave mirror 70, and a housing 10.

  The housing 10 is formed in a box shape by combining, for example, black light-shielding synthetic resin or metal. A display unit 20, a light source unit 30, a plane mirror 60, and a concave mirror 70 are housed inside the housing 10. The housing 10 has an opening 11 at a position facing the windshield 3. The opening 11 is covered with a translucent cover 12. Moreover, the housing | casing 10 also has the function of heat dissipation, and in the metal part, the radiation fin and uneven | corrugated surface which measured the surface area increase are provided in the outer side.

  The light source unit 30 is composed of, for example, a plurality of LEDs (light emitting diodes), and irradiates light from the LEDs toward the display unit 20. An LED is an example of a light source. The display unit 20 receives light from the light source unit 30, generates display light L corresponding to the virtual image (image) V, and irradiates the plane mirror 60 with the generated display light L.

  The flat mirror 60 includes a base material made of, for example, a synthetic resin or a glass material, and a reflective film formed on the surface of the base material by means such as vapor deposition. The plane mirror 60 reflects the display light L emitted from the display unit 20 toward the concave mirror 70.

  The concave mirror 70 is formed in a curved concave shape, and includes a base material made of, for example, a synthetic resin material, and a reflective film formed on the surface of the base material by means such as vapor deposition. The concave mirror 70 reflects the display light L from the plane mirror 60 toward the windshield 3. The display light L reflected by the concave mirror 70 passes through the translucent cover 12 of the housing 10 and reaches the windshield 3, and the display light L reflected by the windshield 3 is shown in FIG. Reach 5 By receiving the display light L, the driver 5 can visually recognize the virtual image V displayed at the front position of the windshield 3.

  (Configuration of display unit)

  As shown in FIG. 3, the display unit 20 includes a display member 21, a transparent member 22, a bezel 23, a transparent adhesive 24, a frame body 25, and a heat conducting member 26.

  The display member 21 is composed of, for example, a transmissive TFT (Thin Film Transistor) liquid crystal panel. The display member 21 displays an image on the display area S of the display surface 21a (front surface) by changing the transmittance of light from the light source unit 30.

  The transparent member 22 is bonded to the display surface 21 a of the display member 21 via a transparent adhesive 24. The transparent member 22 has, for example, a rectangular plate shape and is formed of a glass material. The transparent member 22 is laminated in a size larger than the display region S so as to include the display region S of the display surface 21 a of the display member 21 when viewed from the thickness direction of the transparent member 22. Further, the transparent member 22 is formed to be thicker than the display member 21. Conditions for selecting the material of the transparent member 22 will be described later. In the present example, a thin film layer 221 that reflects infrared rays is provided on the surface of the transparent member 22. The thin film layer 221 is formed on the surface of the transparent member 22 by vapor deposition, sputtering, film attachment, or the like. The thin film layer 221 reflects infrared rays contained in the sunlight Ls, so that the temperature rise of the display member 21 due to the sunlight Ls can be reduced.

  The bezel 23 is configured in a frame shape so as to surround the display member 21 and is formed of, for example, metal or resin. The bezel 23 has a rectangular frame shape along the outer peripheral edge of the display member 21, and includes an opening 23 h that is larger than the display area S of the display member 21. The bezel 23 has an L-shaped cross section over the entire circumference. That is, the bezel 23 is held by the display member 21 using the adhesive portion 231 at a location facing the edge of the back surface (the lower surface in FIG. 3) of the display member 21. The bonding portion 231 is made of, for example, a double-sided tape or an adhesive, and bonds the display member 21 and the bezel 23 to each other. In a state where the bezel 23 is attached to the display member 21, the opening 23 b of the bezel 23 is provided so as to include the display area S of the display member 21. Further, the bezel 23 can be expected to dissipate heat to the outside of the housing 10 while reducing the temperature rise of the display member 21 by transferring heat by contacting the metal part of the housing 10.

  As the transparent adhesive 24, an adhesive means made of an ultraviolet curable transparent resin can be applied. The transparent adhesive 24 is applied to the display surface 21a of the display member 21, and is superposed so that bubbles do not enter between the display member 21 and the transparent member 22. In this state, the transparent adhesive 24 is irradiated with ultraviolet rays to The transparent member 22 is adhered. As the transparent adhesive 24, a thermosetting or moisture curable transparent resin can be applied instead of the ultraviolet curable type. Further, as the transparent adhesive 24, a transparent resin is not applied, but an adhesive sheet can be applied and bonded to form an adhesive structure.

  Further, the transparent adhesive 24 fills a gap (air gap) between the display surface 21a of the display member 21 and the transparent member 22 surface, thereby reducing generation of extra reflected light on each boundary surface and displaying with good visibility. Output is possible. For this reason, the transparent adhesive 24 is preferably made of a material having a refractive index close to that of the transparent member 22 or the display member 21. Further, by filling the gap, heat can be efficiently transferred between the transparent member 22 and the display member 21. For this reason, the transparent adhesive 24 is preferably made of a material having high thermal conductivity.

  The frame body 25 is formed in a frame shape so as to surround the side surface of the transparent member 22. For example, a metal having a large product of specific heat and density, such as aluminum, iron, or copper, is suitable for the frame body 25. In addition, a material having high thermal conductivity such as a high thermal conductivity resin or a graphite laminate can be applied. In addition, a color tone (for example, matte black) or a surface shape (for example, embossing) that hardly reflects light may be formed on the outer peripheral surface of the frame body 25. Further, the frame body 25 is fixed on the display surface 21 a side of the display member 21 on the outer side of the display region S by using the transparent adhesive 24. In this case, the frame body 25 is provided so as to protrude outward from the display member 21. Further, the protruding portion of the frame body 25 can be provided so as to be in contact with a metal portion of the housing 10, and heat can be transferred to the housing 10.

  The heat conducting member 26 is provided between the transparent member 22 and the frame body 25. The heat conducting member 26 is made of a flexible member such as a silicon sheet or grease. The heat conduction member 26 enables heat conduction between the transparent member 22 and the frame body 25. In this case, the heat conduction member 26 is filled in the gap between the transparent member 22 and the frame body 25 in a fluid state, and is cured to the extent that flexibility is maintained, so that the transparent member 22 and the frame body 25 are formed. Contact. In addition, it is desirable that a flow path is set so that air can escape when the heat conducting member 26 is filled in the frame body 25, and through holes or grooves for venting air reaching from the gap to the outside of the frame body 25. Etc. can also be provided.

(Conditions for selecting transparent materials)
Next, conditions for selecting the material and the like of the transparent member 22 will be described along the selection conditions 1 to 3. Examples of the material satisfying the selection conditions 1 to 3 include synthetic quartz and transparent zirconia in addition to the glass material described above. That is, the transparent member 22 only needs to satisfy the selection conditions 1 to 3 and may be formed of, for example, synthetic quartz, transparent zirconia, or the like in addition to the glass material. Furthermore, as long as the transparent member 22 satisfies the selection conditions 1 to 3, the transparent member 22 may be filled with a phase change material.

<Selection condition 1>
A material having a thermal conductivity lower than that of sapphire or quartz (quartz) is selected as the transparent member 22. Here, in general, a material having a high thermal conductivity is expensive. Therefore, when the condition 1 is satisfied, the cost of the display unit 20 can be suppressed. In the vicinity of room temperature, the thermal conductivity of quartz is about 8 W / (m · k), and the thermal conductivity of sapphire is about 40 W / (m · k).

<Selection condition 2>
As shown in FIG. 4, the total heat capacity of the display member 21 and the transparent member 22 is set so that the temperature of the display member 21 is less than the heat resistant temperature Th during the temperature rise time T1. The material of the transparent member 22 is selected so as to satisfy the condition 2. The heat resistant temperature Th is a temperature set based on the Bonanza generation temperature at which the liquid crystal panel (display member 21) is blackened or the heat resistant temperature of the polarizing plate of the liquid crystal panel. The temperature rise time T <b> 1 is expected to be due to sunlight, light from the light source unit 30, and heat generated by a voltage applied to an electrode (not shown) of the display member 21 to the display member 21. It is time to be. In this example, the temperature rise time T <b> 1 is set to a time required for the focus O due to sunlight to pass through the display member 21 as shown in FIG. 7. In addition, in the radiation fin or heat pipe described in Patent Documents 1 and 2, heat dissipation is efficiently started after the temperature rise time T1 has elapsed.

  Specifically, in the head-up display device 100 mounted on the vehicle, the sunlight Ls reaches the display member 21 by going back the path of the display light L as shown in FIG. At this time, since sunlight Ls is condensed by the concave mirror 70, a focal point O where the light gathers is formed on the display member 21. The focal point O moves in the display member 21 as the sun tilts over time. Therefore, the temperature rise time T1 is set based on the time required for the display member 21 to move to the predetermined position. Therefore, after the temperature rise time T1 has elapsed, the focus O does not exist on the display member 21, and thus the temperature rise of the display member 21 is suppressed. The moving path of the focus O in FIG. 7 is an example. Furthermore, in this example, the temperature rise time T1 starts from time t1 when the ignition switch of the vehicle 2 is switched on. The head-up display device 100 starts displaying the virtual image V by starting the light irradiation from the light source unit 30 to the display unit 20 when the ignition switch of the vehicle 2 is switched on.

  The heat capacity is determined by the product of specific heat, density and volume. As the heat capacity increases, the temperature rise of the display member 21 can be delayed. Therefore, it is desirable that the transparent member 22 is set to have a large volume and thus a large heat capacity by forming a thick thickness within a range that does not hinder light transmission, mountability, weight of the entire product, and the like. That is, in the selection condition 2, not only the material of the transparent member 22 but also the volume of the transparent member 22 is an element for satisfying the condition.

ここで、面方向とは、表示部材２１の表示面２１ａに沿う方向をいう。また、断面積は、表示部材２１及び透明部材２２からなる複合材料をその厚さ方向に沿って切った場合の複合材料の断面積をいう。
複合材料の面方向等価熱伝導率は以下の式（２）により算出される。

ここで、全体の厚さは、複合材料の厚さをいう。各層の面方向熱伝達率とは、表示部材２１の熱伝導率又は透明部材２２の熱伝導率をいう。層の厚さとは、表示部材２１の厚さ又は透明部材２２の厚さをいう。層の存在比率は、層の厚さに対して材料が存在する比率をいい、例えば、透明部材２２では空隙がないため１００％となる。なお、透明接着剤２４を含めた複合材料として断面積及び面方向熱伝達率を求めてもよい。 <Selection condition 3>
The thermal resistance in the surface direction of the display surface 21a in the configuration in which the display member 21 and the transparent member 22 are bonded is set to be less than the thermal resistance of the display member 21 to which the transparent member 22 is not bonded. By setting the thermal resistance to be small so as to satisfy this condition 3, in the composite material composed of the display member 21 and the transparent member 22, thermal diffusion is promoted, and temperature unevenness is quickly eliminated. Therefore, before a part of the display member 21 exceeds the heat resistant temperature Th, heat is radiated from the display member 21 to the transparent member 22, thereby suppressing the display member 21 from exceeding the heat resistant temperature Th. The thermal resistance in the surface direction is calculated by the following equation (1).

Here, the surface direction refers to a direction along the display surface 21 a of the display member 21. Moreover, a cross-sectional area means the cross-sectional area of the composite material at the time of cutting the composite material which consists of the display member 21 and the transparent member 22 along the thickness direction.
The plane direction equivalent thermal conductivity of the composite material is calculated by the following equation (2).

Here, the total thickness refers to the thickness of the composite material. The surface direction heat transfer coefficient of each layer refers to the heat conductivity of the display member 21 or the heat conductivity of the transparent member 22. The thickness of the layer refers to the thickness of the display member 21 or the thickness of the transparent member 22. The abundance ratio of the layer refers to a ratio of the material to the thickness of the layer. For example, the transparent member 22 has 100% because there is no void. In addition, you may obtain | require a cross-sectional area and a surface direction heat transfer rate as a composite material containing the transparent adhesive 24. FIG.

  (Function)

  Next, the operation of the head-up display device 100 will be described.

  Since the head-up display device 100 is mounted on the vehicle, the temperature in the passenger compartment tends to rise particularly in summer. Therefore, the ambient temperature Ta of the display member 21 corresponding to the temperature in the passenger compartment rises and becomes close to the heat resistant temperature Th of the display member 21. In such a state, when the ignition switch of the vehicle 2 is turned on, light is emitted from the light source unit 30 to the display member 21. Since the display member 21 absorbs a part of the light by the polarizing plate, the display member 21 receives the light from the light source unit 30 and generates heat. The display member 21 generates heat when a voltage is applied between the electrodes. Furthermore, at this time, when the focus O is positioned on the display member 21 based on the sunlight Ls, the temperature of the display member 21 rises based on the sunlight Ls.

  Even in such a situation, the transparent member 22 is bonded to the display member 21, so that the temperature of the display member 21 rises while the temperature is lower than the heat resistant temperature Th. For this reason, the occurrence of a display abnormality in the display member 21 is suppressed. Moreover, since the focus O of the sunlight Ls does not exist on the display member 21 after the temperature rise is settled, the temperature of the display member 21 is maintained below the heat-resistant temperature Th and even after the temperature rise time T1 has elapsed. Occurrence of display abnormality is suppressed.

  As described above, the head-up display device 100 includes the plate-like display member 21 including the display surface 21 a that emits the display light L corresponding to the image, and the display surface 21 a of the display member 21 via the transparent adhesive 24. And a transparent member 22 to be bonded. The transparent member 22 is made of a material having a thermal conductivity lower than that of quartz, for example, a glass material. In addition, during the time when the temperature of the display member 21 is expected to increase due to the amount of heat applied to the display member 21 (a predetermined time after the head-up display device 100 is activated), the temperature of the display member 21 is The total heat capacity of the display member 21 and the transparent member 22 is set so as to be lower than the heat-resistant temperature Th at which the display is expected to be abnormal.

  As the overall heat capacity of the display member 21 and the transparent member 22 increases, the temperature rise of the display member 21 can be delayed. Therefore, by setting the heat capacity as described above, the temperature of the display member 21 is maintained below the heat resistant temperature Th during the temperature rise time T1, and the display of the display member 21 is suppressed from being abnormal.

  In general, since a material having a high thermal conductivity is expensive, a material having a thermal conductivity lower than that of quartz is adopted as the transparent member 22, thereby reducing the cost of the head-up display device 100. Can be suppressed.

  Furthermore, the transparent member 22 is bonded to the display member 21 so that the thermal resistance is set small. Thereby, in the composite material which consists of the display member 21 and the transparent member 22, thermal diffusion is accelerated | stimulated. Therefore, it is suppressed that a part of display member 21 exceeds the heat-resistant temperature Th and the temperature rises. Further, in the head-up display device 100 of the present embodiment, the heat dissipating fins or heat pipes described in Patent Documents 1 and 2 can be omitted. Therefore, the head-up display device 100 can be configured more compactly.

  The display unit 20 of the head-up display device 100 includes a plate-like display member 21 that emits display light L, and a plate-like transparent member that is bonded to the display surface 21 a of the display member 21 via a transparent adhesive 24. A member 22 and a frame body 25 made of a metal material are provided along the side surface of the transparent member 22. The frame body 25 is provided on the side surface 22c side other than the incident surface 22a and the emission surface 22b through which the display light L in the transparent member 22 mainly passes.

  Thereby, when the display member 21 generates heat, the frame 25 can efficiently extract the heat of the display member 21 via the transparent member 22 without obstructing the optical path passing through the display region S. Therefore, the display device for a vehicle suppresses the occurrence of an abnormality in display as the temperature of the display member 21 increases.

  Moreover, even if there is a dimensional tolerance between the frame 25 and the transparent member 22 by providing the heat conducting member 26 filled between the frame 25 and the side surface of the transparent member 22, these gaps are filled. The heat transfer between the transparent member 22 and the frame body 25 can be performed efficiently.

  Further, the frame body 25 can be expected to transfer heat from the display member 21 in the same manner as the transparent member 22 by being bonded to the display member 21 using the transparent adhesive 24. In addition, by using an adhesive that bonds the transparent member 22 and the display member 21, there is an effect that the process and time when the transparent member 22 and the frame body 25 are assembled to the display member 21 can be reduced.

  Although the present invention has been described by way of example in the configuration of the above-described embodiment, the present invention is not limited to this, and various other configurations can be used without departing from the spirit of the present invention. Of course, it is possible to improve the display and change the display. For example, in the above embodiment, the rectangular parallelepiped flat transparent member 22 is applied, but as shown in FIG. 5, the incident surface of the transparent member 220 (the surface facing the display surface 21a of the display member 21). The area on the emission surface 220b side is smaller than that of 220a, and the side surface 220c of the transparent member 220 is inclined, and the surface 250a facing the frame body 250 can be formed along the side surface 220c. At this time, the frame body 250 can be expected to suppress the separation of the transparent member 220 from the display member 21. Here, in FIG. 5 showing the display unit 200 as another example of the above-described embodiment, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Further, the frame bodies 25 and 250 can be structured to act as holders for holding other members of the transparent members 22 and 220. For example, the frame bodies 25 and 250 can also be used as holders for holding hot mirrors and plane mirrors. May be.

  Moreover, in the said embodiment, although the display member 21 was comprised by the transmissive | pervious TFT liquid crystal panel, an organic EL (OLED: Organic Light Emitting Diode) display may be sufficient. In this case, the light source unit 30 can be omitted.

  In the above embodiment, the display device (display units 20 and 200) is applied to the vehicle head-up display device 100. However, in addition to this, the head-up display device mounted on a vehicle such as an airplane or a ship is used. You may apply. Further, the projection member on which the display light L is projected is not limited to the windshield, but may be a dedicated combiner.

  The present invention relates to a display device for a vehicle, for example, an in-vehicle head-up that is mounted on a moving body including an automobile, a motorcycle, an agricultural machine, or a construction machine, and projects and displays road information such as vehicle information and turn-by-turn display. It is suitable as a display.

100 Head-Up Display Device 2 Vehicle 20, 200 Display Unit (Vehicle Display Device)
21 Display member 21a Display surface 22, 220 Transparent member 221 Thin film layer 23 Bezel 231 Adhesive portion 24 Transparent adhesive 25, 250 Frame body 26 Heat conduction member 30 Light source unit 60 Flat mirror 70 Concave mirror

Claims (5)

A plate-like display member that emits display light;
A plate-like transparent member bonded to the display surface of the display member via a transparent adhesive;
A vehicle display device comprising: a frame body made of a metal material along a side surface of the transparent member. The vehicle display device according to claim 1, further comprising a heat conductive member filled between the frame and a side surface of the transparent member. The vehicle display device according to claim 1, wherein the frame body is bonded to the display member using the transparent adhesive. The vehicle display device according to claim 1, wherein the frame body is provided on a side surface other than an incident surface and an exit surface through which the display light in the transparent member mainly passes. The vehicle display device according to claim 1, wherein the display light is used as projection light for a head-up display.

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