JP6291944B2 - Display device - Google Patents

Description

  The present invention relates to a display device using a heat conductive member in a mounting portion of a case in which a display unit is accommodated.

  The display device includes a liquid crystal display unit and a case in which the liquid crystal display unit is accommodated. The liquid crystal display unit includes a liquid crystal display element called a TFT type and a backlight device that illuminates the liquid crystal display element. A synthetic resin holder for holding the liquid crystal display element and the backlight device, a metal holding frame for fixing the liquid crystal display element and the backlight device to the holder, and a liquid crystal display element disposed behind the holder And a circuit board on which electronic components for lighting a light source to be described later are mounted, a shield case made of steel, and the like. Although not shown, the liquid crystal display element and the circuit board are electrically connected.

  The backlight device includes a cold-cathode tube as a light source, a colorless and transparent light guide member that guides light from the cold-cathode tube incident on the inside from the end face to the back side of the liquid crystal display element, and the back of the light guide member And an optical sheet such as a diffusion sheet or a prism sheet disposed between the liquid crystal display element and the light guide member. The backlight device illuminates the liquid crystal display element from behind so that the display (for example, in the case of a display device for a vehicle, the remaining amount of fuel, temperature, message, etc.) can be seen well.

  Further, the liquid crystal display unit includes a hard main substrate and a frame made of synthetic resin. Each component described above is housed in a frame, and although not shown in detail, it is unitized by fixing a main board to the frame. On the main board, electronic components for a power supply circuit of a display device and a circuit for sending display data to a liquid crystal display element are mounted.

  The case is composed of a divided upper case and lower case, and the upper case is integrally formed with a window portion made of a colorless and transparent synthetic resin and a cover portion made of an impermeable (for example, black) synthetic resin. Is. The cover part consists of a front part and a side part. Further, a substantially cylindrical upper mounting boss is integrally provided at the front portion of the upper case. The lower case is made of an impermeable synthetic resin like the upper case, and has a bottom portion and side portions. Further, the lower case has a lower mounting boss projecting from the bottom corresponding to the upper mounting boss provided on the upper case, and has a substantially cylindrical shape with an opening on the bottom side.

In the liquid crystal display unit, a heat sink made of aluminum is disposed behind the shield case via a heat dissipation sheet made of silicone rubber. The heat dissipation sheet is disposed so as to be sandwiched between the shield case and the heat dissipation plate.

Japanese Patent No. 3896593

  However, the display device described above is a transformer that is an inverter circuit component that turns on a cold cathode tube when heat is generated from a cold cathode tube, an electronic component mounted on a circuit board, and a main substrate. The temperature in the case rises due to high heat generated from the liquid crystal display, and display unevenness may occur in the liquid crystal display element. In addition, when the display device is attached to a motorcycle or an agricultural machine that is exposed to the outside, a ventilation path that communicates the inside and outside of the case cannot be provided in the case because of the necessity of waterproofing and dustproofing. As described above, since a gap is not generated at the joint of the upper case and the lower case, such a tendency is stronger.

Therefore, the heat sink made of aluminum is placed behind the shield case through the heat dissipation sheet made of silicone rubber, so that the heat released from the display unit is dissipated by transferring heat to the heat dissipation sheet and the heat dissipation plate. However, there is a problem that the structure becomes complicated and the cost becomes high.

  The present invention has been made in view of such a point, by dissipating the heat in the case in which the display unit is stored, the heat transmitted to the circuit board, and the like outside the case as much as possible without using a heat sink, An object is to provide a display device with favorable visibility.

In order to achieve the above object, the present invention includes a case and a display unit that includes a circuit board and is accommodated in the case, and the case is integrally formed on the case on the back side of the circuit board. A display device that is screwed to the display unit by screws passing through the mounting portion, wherein the case is a thermally conductive member disposed between the mounting portion and the circuit board And an indentation in which the elastic member is disposed .

  Further, the elastic member has a thickness in a direction in which the screw is tightened rather than the concave portion.

  The elastic member conducts heat released from the circuit board to the mounting portion.

  The display unit includes a boss body to which the screw is fastened.

  According to the present invention, the heat trapped in the case or the heat transmitted to the circuit board is dissipated outside the case through the mounting portion made of the heat conductive member. A display device with good characteristics can be obtained.

Sectional drawing of the display apparatus which shows embodiment of this invention. The partial detail drawing which shows the attaching part of the display apparatus.

  An example in which the present invention is applied to a display device for a vehicle will be described as an embodiment. FIG. 1 is a cross-sectional view of a display device, and FIG. 2 is a partial detail view showing an insert-molded attachment portion.

  The display unit 1 includes a TFT type display element 13 in this embodiment, and includes a holder 5 in which the display element 13 is housed and held, and a lighting member (not shown), which is united.

  The case 2 includes a divided upper case 2A and lower case 2B. The upper case 2A has a window portion made of a colorless and transparent synthetic resin and a cover portion made of an impermeable (for example, black) synthetic resin. Are integrally formed. An attachment boss (attachment part) 22 is insert-molded in the lower case 2B, and the bottom part 21 side is opened. Further, the lower case 2 </ b> B has a recess 23 formed by a gap in which the heat transfer sheet 31 is disposed between the mounting boss 22 and the circuit board 8.

  The mounting boss 22 of the lower case 2B in the present embodiment is made of aluminum or copper which is a metal material having good thermal conductivity. The mounting boss 22 has a substantially cylindrical shape provided with a through hole 22a and a peripheral wall 22b, and is integrally formed with the lower case 2B by a method such as insert molding in a state where the bottom 21 side of the lower case 2B is opened.

  In the present embodiment, the holder 5 is made of a metal material and is disposed so as to cover the outer peripheral side of the display element 13. Although not shown, an FPC extends from the display element 13 and is connected to the circuit board 8 located behind.

  The heat transfer sheet 31 in the present embodiment is an insulating member made of, for example, a silicone rubber sheet, and is in contact with the mounting boss 22 so that the heat of the circuit board 8 is transferred to the mounting boss 22 via the heat transfer sheet 31. Is arranged. The heat transfer sheet 31 has an annular shape in which a through hole 31a is formed at the center so as to be disposed in the recess 23 provided in the lower case 2B. Further, since the heat transfer sheet 31 has a thickness in the direction in which the screw is tightened with respect to the recess 23, the heat transfer sheet 31 can be reliably brought into contact with the circuit board 8.

  The circuit board 8 is provided with a through hole 81a through which the screw 24 that has passed through the mounting boss 22 formed integrally with the lower case 2B passes.

  The boss body 9 is formed on the back surface side of the display unit 1 by heat welding or the like, and a screw 24 penetrating the mounting boss 22, the heat transfer sheet 31, and the circuit board 8 is fastened.

  The assembly of the display unit 1 to the case 2 will be described. In the present embodiment, the heat transfer sheet 31 is disposed in the recess 23 and the screw 24 is inserted into the opening space of the mounting boss 22, and then the screw 24 penetrating the heat transfer sheet 31 and the circuit board 8 is attached to the mounting boss body. Tightened to 9.

  Thus, the case 2 has the recess 23 between the circuit board 8 and the heat transfer sheet 31 made of a heat conductive member is disposed in the recess 23, so that the display unit 1, the electronic component 7, etc. The heat generated in the case 2 and trapped in the case 2 or transmitted to the circuit board 8 is transmitted from the circuit board 8 to the mounting boss 22 and the bottom 21 of the lower case 2B.

In addition, since a part of the heat transmitted to the mounting boss 22 is also transmitted to the bottom 21 of the lower case 2B, a heat radiation effect can be expected in a wide range of the lower case 2B, and a heat sink is provided while maintaining waterproof and dustproof properties. However, heat generated from the display unit 1 or the electronic component 7 or the like and trapped in the case 2 or transmitted to the circuit board 8 is transmitted from the circuit board 8 to the mounting boss 22 and the bottom portion 21 of the lower case 2B to the outside. Since it is diffused, it is possible to provide a display device with good visibility while suppressing the temperature rise of the liquid crystal display element 3.

  Further, since the mounting boss 22 made of a good heat conductive material is integrally formed with the lower case 2B, the number of components of the lower case 2B can be reduced, and the assembly workability of the display device can be facilitated.

  The heat transfer sheet 31 may be a synthetic resin having flexibility, and in the case of insulation, a silicone rubber sheet or the like is suitable.

  Further, since the bottom portion 21 is formed at a height equivalent to at least a part of the opening portion of the mounting boss 22, it is possible to easily check whether or not the screw 24 is correctly tightened.

  Further, the display device in which the display unit 1 is accommodated in the case 2 has been described as an embodiment. However, in addition to the display unit 1, an analog speedometer, tachometer, or the like may be accommodated in the case 2. good. Further, a liquid crystal display element, for example, a fluorescent display tube may be used. Further, it is only necessary to include a circuit board on which at least a display element, an illumination member that illuminates the display element, an electronic component for displaying the display element, and the like are mounted.

DESCRIPTION OF SYMBOLS 1 Display unit 2 Case 2A Upper case 2B Lower case 8 Circuit board 9 Boss body 21 Bottom part 22 Mounting boss (attachment part)
22a through hole 22b peripheral wall 23 recess 24 screw (fixing means)
31 Heat transfer sheet (elastic member)
31a Through hole 81a Through hole

Claims (4)

A case and a display unit including a circuit board and housed in the case;
The case has a mounting portion integrally formed with the case on the back side of the circuit board, and is a display device that is screwed to the display unit by a screw that penetrates the mounting portion,
The display device according to claim 1, wherein the case includes an elastic member made of a heat conductive member disposed between the mounting portion and the circuit board, and a concave portion in which the elastic member is disposed . The display device according to claim 1 , wherein the elastic member has a thickness in a direction in which the screw is tightened with respect to the recess.   The display device according to claim 1, wherein the elastic member conducts heat released from the circuit board to the mounting portion. The display device according to claim 1, wherein the display unit includes a boss body to which the screw is tightened.

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