JP2008094283A - On-vehicle display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the necessity of application of a moisture-proof agent by providing structure to prevent dew condensation on one face side of circuit boards mounted on an on-vehicle display unit. <P>SOLUTION: The on-vehicle display unit mounted to an instrument panel of an automobile is provided with a front panel comprising a front wall part with a front face serving as a design face and a peripheral wall part projecting rearward from the peripheral edge of the front wall part; a display panel arranged on the rear face side of the front panel; the circuit boards opposingly arranged on the rear face of the display panel and mounted with an electronic component at least on the front face; and a rear cover arranged in the rear of the circuit boards and comprising a rear wall part and a peripheral wall part projecting forwardly from the peripheral edge of the rear wall part. The peripheral edges of the display panel and circuit boards arranged to oppose to each other are surrounded by the peripheral wall part of the front panel and/or rear cover, and a gap between the display panel and circuit boards is surrounded by the peripheral wall part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle display unit, and more specifically, is attached to an instrument panel of an automobile and used as an audio unit, a car navigation system, or the like.

2. Description of the Related Art Conventionally, an in-vehicle display unit mounted on an automobile and used as a car navigation system or the like includes a circuit board on which electronic components are mounted in order to control display of various information on a display panel.
When outside air containing moisture flows into such an in-vehicle display unit and condensation occurs on the circuit board, migration occurs between the leads of the electronic components or between the electrodes due to the water droplets, and the insulated conductor There is a problem of short circuiting.

Therefore, in JP-A-8-32214 (Patent Document 1), as shown in FIG. 4, a moisture-proofing agent 3 is applied to a place where the electronic component 2 of the circuit board 1 is mounted so that no migration occurs. Yes.
However, the configuration disclosed in Patent Document 1 requires a step of applying a moisture-proofing agent in the printed circuit board manufacturing process, and particularly on a circuit board on which electronic components are mounted on both sides. There is a problem that a process of applying a moisture-proofing agent is required, which increases the manufacturing process and increases the cost.

JP-A-8-32214

  The present invention has been made in view of the above problems, and makes it unnecessary to apply a moisture-proofing agent by preventing the formation of condensation on one surface side of a circuit board mounted on a vehicle-mounted display unit. It is an issue.

In order to solve the above problems, the present invention is an in-vehicle display unit attached to an instrument panel of an automobile,
A front panel comprising a front wall portion whose front surface is a design surface and a peripheral wall portion protruding rearward from the periphery of the front wall portion;
A display panel that is disposed on the rear surface side of the front panel, and the display surface is viewed from the front side of the front panel through an opening or a transmissive material provided in the front panel;
A circuit board disposed opposite to the rear surface of the display panel and having electronic components mounted on at least the front surface;
A rear cover that is disposed behind the circuit board and includes a rear wall portion and a peripheral wall portion protruding forward from a peripheral edge of the rear wall portion;
The periphery of the display panel and the circuit board that are arranged to face each other is surrounded by a peripheral wall portion of the front panel and / or the rear cover, and a gap between the display panel and the circuit board is surrounded by the peripheral wall portion. A display unit is provided.

  According to the in-vehicle display unit of the present invention, the display panel and the circuit board are surrounded by the front panel and / or the peripheral wall of the rear cover and the gap between the display panel and the circuit board is surrounded. The outside air hardly flows between the substrates, and the front surface of the circuit board is opposed to the rear surface of the display panel, so that the heat generated by the display panel is maintained at a high temperature that does not cause condensation on the front surface of the circuit board. Therefore, no dew condensation occurs on the front surface of the circuit board, and it is not necessary to apply a moisture-proofing agent to the place where the electronic component is mounted on the front surface side of the circuit board.

The distance between the display panel and the peripheral edge of the circuit board and the peripheral wall of the front panel and / or the rear cover surrounding the peripheral edge is preferably 3 to 5 mm.
If the distance between the peripheral edge of the display panel and the circuit board and the peripheral wall portion is smaller than 3 mm, it is difficult to assemble the front panel and the rear cover to the display panel and the circuit board. This is because outside air easily flows into the gaps between the circuit boards.

It is preferable that the circuit board has an electronic component mounted on a rear surface facing the rear cover and a moisture proofing agent is applied thereto, while a moisture proofing agent is not applied on the surface facing the display panel.
According to the above configuration, when manufacturing a circuit board having electronic components mounted on both sides, it is not necessary to apply a moisture-proofing agent on both sides, and it is only necessary to apply the moisture-proofing agent only on the rear surface side. The cost can be reduced.
In addition, examples of the moisture-proofing agent include tuffy manufactured by Hitachi Chemical Co., Ltd.

On at least one side of the peripheral edges of the display panel and the circuit board, a switch device connected to the circuit board is disposed between the front panel and / or the peripheral wall of the rear cover.
Thus, the member surrounding the periphery of the display panel and the circuit board is not limited to the peripheral wall portion of the front panel and the rear cover, and may be another member used for an in-vehicle display unit such as a switch device.

The distance between the display panel and the circuit board is preferably 3 to 7 mm, and more preferably 5 mm.
This is because if the distance between the display panel and the circuit board is smaller than 3 mm, the circuit on the rear surface of the display panel and the circuit on the front side of the circuit board may be short-circuited due to vibration. is there. In particular, when the distance is 5 mm, the display panel and the circuit board can be reliably insulated and the inflow of outside air can be prevented.

Preferably, the display panel is a liquid crystal panel, and the circuit board is for controlling the liquid crystal panel.
According to the above configuration, the liquid crystal panel always operates when a current is applied to the conductor of the circuit board, so that a high temperature is maintained so that condensation does not occur due to the heat generated by the liquid crystal panel when the circuit board is energized. It is possible to prevent migration from occurring.
In addition, when a direct-type backlight is used for the liquid crystal panel, the light source can be disposed opposite to the entire surface of the circuit board, and the heat generated by the light source can cause a high temperature state over the entire surface of the circuit board. Can be maintained. This makes it unnecessary to apply the moisture-proofing agent no matter where the electronic component is mounted on the front side of the circuit board.

  As described above, according to the present invention, the peripheral edge of the display panel and the circuit board is surrounded by the peripheral wall portion of the front panel and / or the rear cover, and the gap between the display panel and the circuit board is surrounded by the peripheral wall portion. Keeping the front of the circuit board facing the back of the display panel is difficult for outside air to flow between the panel and the circuit board, and maintains a high temperature that does not cause condensation on the front of the circuit board due to the heat generated by the display panel. Yes. Therefore, no dew condensation occurs on the front surface of the circuit board, and it is not necessary to apply a moisture-proofing agent to the place where the electronic component is mounted on the front surface side of the circuit board.

Embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of the present invention, and an in-vehicle display unit 10 is attached to an instrument panel of an automobile and is used for a car navigation system.

  As shown in FIG. 1, the in-vehicle display unit 10 includes a front panel 11 having a transparent display cover 20 (transmission material) and a switch device 19 and a front surface serving as a design surface. The liquid crystal panel 12 disposed on the rear surface side, the printed boards 13 and 14 (circuit boards) disposed opposite to the rear surface of the liquid crystal panel 12 and stacked via the spacers 21, and the rear surface of the printed board 14 are covered. And a rear cover 15.

  The printed circuit board 13 disposed opposite to the rear surface of the liquid crystal panel 12 is connected to the liquid crystal panel 12 via the flexible flat cable 12a and the terminal 12b, and functions as a control for the liquid crystal panel 12. The printed circuit board 13 and the liquid crystal panel 12 are arranged to face each other at a close position with a gap of 5 mm. As shown in FIG. 3A, an electronic component 16 having a terminal pitch of 0.5 mm is mounted on the front surface 13a of the printed circuit board 13 facing the rear surface of the liquid crystal panel 12. A moisture-proof agent is not applied to the mounting position of the component 16. On the other hand, as shown in FIG. 3B, a moisture-proof agent 18 is applied to the mounting position of the electronic component 17 on the rear surface 13 b of the printed circuit board 13.

As shown in FIG. 2, the peripheral edges of the liquid crystal panel 12 and the printed circuit board 13 that are arranged opposite to each other are peripherally protruded rearward from the peripheral edge of the front wall 11 a of the front panel 11 and the peripheral edge of the rear wall 15 a of the rear cover 15. Is surrounded by a peripheral wall portion 15b protruding forward, and a gap between the liquid crystal panel 12 and the printed circuit board 13 is surrounded by the peripheral wall portions 11b and 15b. In the present embodiment, the interval between the peripheral edge of the liquid crystal panel 12 and the printed board 13 and the peripheral wall portions 11b and 15b surrounding the peripheral edge is set to 3 to 5 mm.
In addition, a switch device 19 connected to the printed circuit board 13 is arranged between the front panel 11 and the peripheral wall portions 11 b and 15 b of the rear cover 15 on the lower side of the peripheral edges of the liquid crystal panel 12 and the printed circuit board 13. The switch device 19 surrounds the lower side gap between the liquid crystal panel 12 and the printed board 13.

The liquid crystal panel 12 and the printed boards 13 and 14 are fixed by bolting, and the front panel 11 is covered on the front side of the liquid crystal panel 12 fixed by bolting, and the rear cover 15 is covered on the rear side of the printed board 14. These front panel 11, printed circuit boards 13, 14 and rear cover 15 are fixed by bolting.
In this assembled state, the display surface of the liquid crystal panel 12 can be viewed from the front side of the front panel 11 through the transparent display cover 20 assembled in the opening 11c of the front panel 11.

According to the above configuration, the peripheral edges of the liquid crystal panel 12 and the printed board 13 are surrounded by the peripheral walls 11b and 15b of the front panel 11 and the rear cover 15, and the gap between the liquid crystal panel 12 and the printed board 13 is surrounded by the peripheral walls 11b and 15b. Therefore, it is difficult for outside air including moisture to flow between the liquid crystal panel 12 and the printed board 13. In addition, the front surface of the printed circuit board 13 is opposed at a position close to the rear surface of the liquid crystal panel 12, and the gap between the liquid crystal panel 12 and the printed circuit board 13 is surrounded by the peripheral wall portion as described above, and the flow of air in the gap is prevented. By reducing the heat dissipation and reducing the heat dissipation, a high temperature is maintained such that no condensation occurs on the front surface of the printed circuit board 13 due to the heat generated by the liquid crystal panel 12. Therefore, condensation does not occur on the front surface of the printed circuit board 13, and it is not necessary to apply a moisture-proofing agent to the place where the electronic component 16 is mounted on the front surface side of the printed circuit board 13. Thereby, the process of apply | coating a moisture-proof agent in the manufacturing process of the printed circuit board 13 can be reduced, and cost reduction can be achieved.
In the present embodiment, the display panel is a liquid crystal panel, but may be another display such as a fluorescent display tube.
Alternatively, the peripheral edges of the liquid crystal panel 12 and the printed board 13 may be surrounded by only one of the peripheral wall portion 11b of the front panel 11 and the peripheral wall portion 15b of the rear cover 15.

It is a disassembled perspective view of the vehicle-mounted display unit of embodiment of this invention. It is sectional drawing of a vehicle-mounted display unit. FIG. 2A shows a printed circuit board, FIG. 2A is a drawing showing a front surface, and FIG. 2B is a drawing showing a rear surface. It is drawing which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 In-vehicle display unit 11 Front panel 11a Front wall part 11b Perimeter wall part 12 Liquid crystal panel 13, 14 Printed circuit board 15 Rear cover 15a Rear wall part 15b Perimeter wall part 16, 17 Electronic component 19 Switch apparatus

Claims (5)

An in-vehicle display unit attached to an instrument panel of an automobile,
A front panel comprising a front wall portion whose front surface is a design surface and a peripheral wall portion protruding rearward from the periphery of the front wall portion;
A display panel that is disposed on the rear surface side of the front panel, and the display surface is viewed from the front side of the front panel through an opening or a transmissive material provided in the front panel;
A circuit board disposed opposite to the rear surface of the display panel and having electronic components mounted on at least the front surface;
A rear cover that is disposed behind the circuit board and includes a rear wall portion and a peripheral wall portion protruding forward from a peripheral edge of the rear wall portion;
The periphery of the display panel and the circuit board that are arranged to face each other is surrounded by a peripheral wall portion of the front panel and / or the rear cover, and a gap between the display panel and the circuit board is surrounded by the peripheral wall portion. Display unit.   2. The circuit board according to claim 1, wherein an electronic component is mounted on a rear surface facing the rear cover and a moisture-proofing agent is applied to the circuit board, while a moisture-proofing agent is not applied to a surface facing the display panel. In-vehicle display unit.   The switch device connected to the circuit board is disposed between the front panel and / or the peripheral wall of the rear cover on at least one side of the peripheral edges of the display panel and the circuit board. Item 3. A vehicle-mounted display unit according to Item 2.   The in-vehicle display unit according to any one of claims 1 to 3, wherein a distance between the display panel and the circuit board is 3 to 7 mm.   The in-vehicle display unit according to any one of claims 1 to 4, wherein the display panel is a liquid crystal panel, and the circuit board is used for controlling the liquid crystal panel.

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