JP7298602B2 - Display device - Google Patents

Description

The present invention relates to a display device mounted on a vehicle such as an automobile.

2. Description of the Related Art Vehicles such as automobiles and motorcycles are equipped with a display device including a needle-type speedometer, a tachometer, and a liquid crystal display device for digitally displaying necessary information. Such a display device has a dial plate having designs such as scales, numerals, characters, symbols, etc. printed in the form of cutout characters, and pointers indicating these designs. Designs and pointers convey information to viewers by the presence or absence of illumination and colors by transmitting light from the light source on the circuit board provided on the back side through the light guide, and provide design. ing.

The light guide is arranged with respect to the light source after its shape and arrangement are designed so as to efficiently guide the light from the light source. For example, as shown in Patent Document 1, the light guide has positioning pins that are inserted into holes provided in the circuit board. The light guide is positioned relative to the light source by being positioned with the circuit board via the positioning pin.

Japanese Patent Application Laid-Open No. 2004-151028

In the display device, members around the light source may be affected by heat from an external heat source such as sunlight or an internal heat source such as heat generated by the light source, and may then contract. Here, the light guide is made of a synthetic resin such as PMMA (Polymethyl methacrylate). Further, the circuit board is made of a rigid wiring board in which a wiring pattern is formed on a flat glass epoxy base material such as FR-4 (Flame Retardant-4). In this case, the light guide is made of a material having a large coefficient of thermal expansion with respect to the circuit board. Therefore, the light guide body affected by the heat moves relative to the circuit board with the positioning pin as a starting point. As a result, the light guide may be displaced with respect to the light source, and the desired brightness may not be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device capable of maintaining the light guide efficiency of a light guide.

In order to solve the above-described problems, the display device according to the present invention includes: a circuit board having a light source; a light guide that guides the light from the light source to an illumination object; and a case that supports the circuit board and the light guide. a first positioning portion that positions the case with respect to the circuit board; and a position that positions the light guide with respect to the case and is provided at a position facing the first positioning portion with respect to the light source. and a second positioning portion, wherein the case expands or contracts with the first positioning portion as a starting point during thermal expansion or thermal contraction, and the light guide body expands or contracts during thermal expansion or thermal contraction. It expands or contracts from the second positioning portion as a starting point .

In the display device according to the present invention, the light guide efficiency of the light guide can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS The front view which shows the display apparatus which is embodiment of the display apparatus which concerns on this invention. Sectional drawing which follows the II-II line of FIG. FIG. 3 is an exploded view of FIG. 2 mainly showing the circuit board, middle case and light guide; FIG. 2 is a cross-sectional view along line III-III in FIG. 1, showing a modification of the display device; FIG. 2 is a cross-sectional view taken along line III-III in FIG. 1, showing another modification of the display device;

An embodiment of a display device according to the present invention will be described with reference to the accompanying drawings. The display device according to the present invention is mounted, for example, on vehicles such as automobiles and motorcycles, ships, agricultural machinery, and construction machinery. In this embodiment, the display device according to the present invention will be described using an example in which the display device is mounted in the instrument panel of an automobile.

FIG. 1 is a front view showing a display device 1 which is an embodiment of a display device according to the present invention.
FIG. 2 is a cross-sectional view taken along line II--II of FIG.

3 is an exploded view of FIG. 2 mainly showing the circuit board 30, the middle case 51 and the light guide 40. FIG.

In the following description, the "front (front) side" is the front side in FIG. 1 and the upper (change: left) side (dial plate 20 side) in FIG. means. The "back (rear) side" means the back side in FIG. 1 and the lower (change: right) side (outer case 52 side) in FIG.

The display device 1 has a speedometer 2 and an engine tachometer 3 . The speedometer 2 is a pointer-type instrument that displays the speed of the vehicle. The engine speed meter 3 is a pointer-type instrument that displays the engine speed of the vehicle.

The display device 1 mainly has pointers 10 , a dial 20 , a circuit board 30 , a light guide 40 , a case 50 and a dial 60 .

The pointer 10 is connected to the tip of a pointer shaft 35 of a pointer driving portion 31 provided on a circuit board 30, and rotates on a plane parallel to the dial 20 on the dial front surface 20a side. The pointer 10 rotates and points to a design 21 (indicator) such as a scale or numbers formed on a dial 20 corresponding to the speed or engine speed of the vehicle. The pointer 10 has a light-emitting portion 11 and a cap 12 .

The light-emitting portion 11 is made of resin (for example, polycarbonate) having transparency (translucency), and is a pointer-shaped member. The light emitting portion 11 receives light from the light source 32 and guides the light to the tip side while reflecting the light.

The cap 12 is made of black resin (for example, ABS resin) and covers the vicinity of the rotation center of the light emitting section 11 from the front side to shield unnecessary portions. The cap 12 has a sheath portion 13 and side portions 14 . The sheath portion 13 exposes the light-emitting portion 11 in a stripe shape. The side portion 14 protrudes (extends) from the peripheral edge 15 of the cap 12 toward the dial front surface 20a.

The dial 20 is a thin plate member provided on the front side of the light source 32 and on the back side of the hands 10 . The dial 20 has a base material and a light shielding layer.

The substrate is a plate-like (sheet-like) member made of a resin (for example, polycarbonate) having transparency (light-transmitting property).

The light-shielding layer is a printed layer printed with black light-shielding ink and formed on the front side (or back side) of the substrate. The light shielding layer has a cutout character portion corresponding to the shape of the design 21 . The design 21 is characters, symbols, and scales and numbers indicated by the pointer 10 . The dial 20 lights up and displays the design 21 by transmitting light from a light source (not shown) for the design 21 .

The periphery of the dial 20 , that is, the periphery of the speedometer 2 and the engine speed indicator 3 is covered with a decorative ring 23 . The decoration ring 23 is made of black resin (for example, ABS resin) coated with silver, and is a ring member fitted to the periphery of the speedometer 2 and the engine tachometer 3 .

In addition to the dial 20, the display device 1 has a dial 25 arranged around the speedometer 2 and the engine tachometer 3, although detailed description thereof is omitted in this embodiment. .

The circuit board 30 is, for example, a glass epoxy board based on FR4 (Flame Retardant Type 4), and is provided behind the middle case 51 on the dial back surface 20b side. The circuit board 30 mainly has a pointer driving section 31 , a light source 32 , and a control section including drivers for the light source 32 and the pointer driving section 31 .

The control unit has a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and executes predetermined arithmetic processing according to a program written in the ROM, for example. The control unit, for example, acquires various vehicle information from an ECU (Electronic Control Unit) of the vehicle. The control unit turns on the light source 32 and drives the pointer driving unit 31 based on the acquired information.

The pointer drive unit 31 is composed of a stepping motor or the like that rotates the pointer shaft 35 in accordance with the input vehicle speed and engine speed. The pointer shaft 35 extends vertically from the circuit board 30 toward the front side.

The light source 32 is provided on the front surface of the circuit board 30 and illuminates the front side. The light source 32 is, for example, a top-view type (top emission type) LED (Light Emitting Diode). Three light sources 32 are evenly provided around the pointer driving portion 31 (pointer shaft 35). Light sources (not shown) for the designs 21 are provided according to the number and positions of the designs 21 of the display device 1 .

The light guide 40 is made of transparent resin (for example, polymethyl methacrylate (PMMA)). The light guide body 40 is formed in a substantially cylindrical shape surrounding the pointer shaft 35 with a certain gap therebetween so as not to hinder the rotation of the pointer shaft 35. The light from the light source 32 is guided to. The shape and position of the light guide 40 are set so that the light from the light source 32 is received without loss on the light receiving surface 41 and guided to the light emitting section 11 . Therefore, the position of the light guide 40 (light receiving surface 41) with respect to the light source 32 (circuit board 30) is important.

The case 50 has middle cases 51 and 53 and an outer case 52 .

The middle case 51 (the first middle case 51) and the middle case 53 (the second case 53) are made of light-blocking synthetic resin (for example, polypropylene) such as white. The middle case 51 has the dial 20 mounted on its front surface and accommodates the light guide 40 inside. The middle case 53 has the dial plate 25 mounted on the front surface and the circuit board 30 fixed on the rear surface. The middle case 51 is fixed to the middle case 53 and the circuit board 30 from the front surface of the dial 25 . That is, the middle cases 51 and 53 support the circuit board 30 and the light guide 40 . Hereinafter, the term “middle case” simply means the first middle case 51 .

The outer case 52 is made of black or other light-shielding resin (for example, polypropylene), accommodates the inner case 51 , the inner case 53 , and the circuit board 30 therein, and forms the back surface of the display device 1 .

The facing 60 is made of a light-shielding resin (for example, polypropylene) of black color or the like. The dial 60 is attached to the front side of the outer case 52 . The facing 60 also functions as a case on the front side of the display device 1 . The dial 60 has a cover 62 made of translucent resin (for example, PMMA or inorganic glass) on the front side. The cover 62 covers the opening formed by the dial peripheral edge 63 so that dust and the like do not enter the inside of the display device 1 .

Next, the positioning structure between the middle case 51, the circuit board 30 and the light guide 40 will be described in detail.

The display device 1 includes a first positioning portion 80 for positioning the middle case 51 (case) with respect to the circuit board 30 and a second positioning portion 90 for positioning the light guide 40 with respect to the middle case 51 . have.

The first positioning portion 80 has a board hole 81 and a case positioning pin 82 . The board hole 81 is provided in the circuit board 30 and has an insertion direction perpendicular to the surface of the circuit board 30 . The case positioning pin 82 is provided on the middle case 51 and is inserted into the board hole 81 with a small gap to position the middle case 51 with respect to the circuit board 30 . The first positioning portion 80 is preferably provided at a position close to the light source 32 from the viewpoint of preventing positional deviation between the light source 32 and the light guide 40 . For example, within the radius of rotation (for example, 50 mm) of the speedometer 2 and the engine tachometer 3, that is, within the length of the pointer 10 (the distance from the center of rotation to the tip of the light emitting unit 11), the first positioning unit Preferably 80 is provided. When the light source for the design 21 is arranged at a position farther than the light source 32 with respect to the pointer shaft 35, a second One positioning portion 80 may be provided.

The display device 1 further has a first detent 85 so that the middle case 51 does not rotate on the circuit board 30 around the case positioning pin 82 . The first detent 85 is a board detent hole 86 provided in the circuit board 30 and a case detent pin 87 provided in the middle case 51 . The board anti-rotation hole 86 has a small gap with the case anti-rotation pin 87 so that the middle case 51 suppresses the movement of the case anti-rotation pin 87 in the direction of rotation about the case positioning pin 82 . On the other hand, in consideration of workability during assembly, a gap is provided in the radial direction of rotation (the direction connecting the case positioning pin 82 and the case anti-rotation pin 87).

The second positioning portion 90 is located at a position facing the first positioning portion 80 with respect to the light source 32 (axis Z3) (on a straight line connecting the first positioning portion 80 and the light source 32 and positioned between the light source 32 and the pointer shaft 35). is provided at a position opposite to the reference). The second positioning portion 90 has a case hole 91 and a light guide positioning pin 92 . The case hole 91 is provided in the middle case 51 so that the light guide positioning pin 92 is inserted in the same direction as the substrate hole 81 (regardless of the positive or negative direction). The light guide positioning pin 92 is provided on the light guide 40 and is inserted into the case hole 91 with a small gap to position the light guide 40 with respect to the middle case 51 .

The display device 1 further has a second detent 95 to prevent the light guide 40 from rotating on the inner case 51 around the light guide positioning pin 92 . The second detent 95 is a case detent hole 96 provided in the middle case 51 and a light guide detent pin 97 provided in the light guide 40 . Similar to the substrate rotation prevention hole 86 , the case rotation prevention hole 96 has a small gap from the substrate rotation prevention hole 86 in the direction in which the light guide 40 rotates about the light guide positioning pin 92 . On the other hand, the case anti-rotation hole 96 has a gap in the radial direction of rotation (the direction connecting the light guide positioning pin 92 and the light guide anti-rotation pin 97). The number of the first and second detents 85 and 95 is not limited as long as they can prevent rotation around the case positioning pin 82 and the light guide body positioning pin 92 .

Next, in the display device 1, the influence of the heat generated by the light source 32 on the middle case 51 and the light guide 40 will be described.

When the light source 32 emits light, heat is generated. Due to this heat, the circuit board 30, the inner case 51, and the light guide 40, which are members surrounding the light source 32, are affected by the heat. The circuit board 30 has a smaller coefficient of thermal expansion (thermal contraction) than the inner case 51 and the light guide 40, and is less susceptible to heat. Therefore, the middle case 51 and the light guide 40 are more susceptible to thermal expansion and contraction than the circuit board 30 .

The middle case 51 is positioned and supported by the circuit board 30 at the first positioning portion 80 . Therefore, the middle case 51 expands or contracts with the first positioning portion 80 as a starting point during thermal expansion or thermal contraction. For example, as shown in FIG. 3, the middle case 51 expands with the axis Z1 of the case positioning pin 82 as a base point. As a result, the second positioning portion 90 in which the light guide 40 is positioned moves in the arrow X1 direction.

Also, the light guide 40 is positioned and supported by the middle case 51 at the second positioning portion 90 . Therefore, the light guide 40 expands or contracts with the second positioning portion 90 as a starting point during thermal expansion or thermal contraction. For example, the light guide 40 expands with the axis Z2 of the light guide positioning pin 92 as a base point. As a result, the light receiving surface 41 of the light guide 40 moves in the arrow X2 direction.

However, the first positioning portion 80 and the second positioning portion 90, which have similar coefficients of thermal expansion (thermal contraction), are separated from each other by an axis Z3, which is an axis in the front-rear direction (perpendicular to the circuit board 30) passing through the light source 32. are placed facing each other. Therefore, the movement of the second positioning portion 90 in the direction of the arrow X1 and the movement of the light receiving surface 41 in the direction of the arrow X2 are offset (cancelled), and as a result, the light receiving surface 41 moves with respect to the axis Z3. There is no change (the position hardly changes).

In such a display device 1 , the light guide 40 is not positioned on the circuit board 30 but positioned via the middle case 51 . As a result, the influence of thermal expansion and thermal contraction due to the heat of the light source 32 can be minimized. Therefore, the display device 1 can maintain the light guide efficiency of the light guide 40 .

Moreover, the light guide 40 is provided so as to surround the pointer shaft 35 while having a certain gap from the pointer shaft 35 . This gap must be maintained so as not to hinder the driving of the pointer shaft 35 . In the display device 1 according to the present embodiment, movement of the middle case 51 and the light guide 40 with respect to the circuit board 30 due to thermal expansion and contraction is offset with respect to the axis Z4 of the pointer shaft 35 as well as the light receiving surface 41 described above. can do. Therefore, the display device 1 can keep the gap between the light guide 40 and the pointer shaft 35 constant.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, the illumination object through which the light guide guides the light from the light source may be the design of the dial instead of or in addition to the hands 10 described above.

FIG. 4 is a cross-sectional view along line III-III in FIG. 1 showing a modification of the display device 1. As shown in FIG.

The display device 1 has a display panel 102 such as a liquid crystal display panel in addition to the speedometer 2 and the engine speed counter 3 . The display device 1 has a light source 103 for the design 107 on the circuit board 30 . The light guide 104 guides the light from the light source 103 to the design 107 of the dial 106 provided on the front side of the display panel 102 so as to cover the display panel 102 . The dial 60 is provided on the front side of the dial 106 and covers the shielding portion of the dial 106 .

The display device 1 has a first positioning section 110 and a second positioning section 120 .

The first positioning portion 110 has a board hole 111 and a circuit board case positioning pin 112, substantially similar to the first positioning portion 80. As shown in FIG. The first positioning portion 110 is provided on the surface of the circuit board 30 on which the display panel 102 is not arranged. The display device 1 also has a first detent (not shown), substantially similar to the first detent 85 .

The second positioning portion 120 positions the light guide 104 with respect to the middle case 51 . The second positioning portion 120 is positioned at a position facing the first positioning portion 110 with respect to the light source 103 (on a straight line connecting the first positioning portion 110 and the light source 103 and facing the light source 103 as a reference). is provided. The second positioning portion 120 has a light guide hole 121 and a light guide case positioning pin 122 . The light guide hole 121 is provided in the light guide 104 so that the light guide case positioning pin 122 is inserted in the same direction as the board hole 111 (regardless of the positive or negative direction). . The light guide case positioning pin 122 is provided in the middle case 51 and is inserted into the light guide hole 121 to position the light guide 104 with respect to the middle case 51 . Also, substantially similar to the second detent 95, the display device 1 further has a second detent (not shown).

The display device 1 shown in FIG. 4 as such a modified example has the first positioning portion 110 and the second positioning portion 120, thereby minimizing the effects of thermal expansion and thermal contraction due to the heat of the light source 103. can be suppressed. As a result, positional deviation of the light receiving surface 105 of the light guide 104 can be reduced with respect to the design 107 on the dial 106, and the light guide efficiency of the light guide 104 can be maintained.

FIG. 5 is a cross-sectional view along line III-III of FIG. 1 showing another modification of the display device 1. As shown in FIG. Components and portions corresponding to those of the display device 1 are denoted by the same reference numerals, and overlapping descriptions are omitted.

The display device 1 of FIG. 5 differs from the display device 1 of FIG. 4 in that it has a third positioning portion 210 for reducing positional deviation of the dial 106 and the dial 60 with respect to the light source 103 and the light guide 104. It is a point.

The third positioning portion 210 positions the dial 106 and the dial 60 with respect to the middle case 205 . Similar to the second positioning portion 120, the third positioning portion 210 is located at a position facing the first positioning portion 110 with respect to the light source 103 (on a straight line connecting the first positioning portion 110 and the light source 103, 103).

The third positioning portion 210 has a dial hole 211 , a dial hole 212 , and a dial case positioning pin 213 . The dial hole 211 is provided in the dial 106 so that the dial case positioning pin 213 is inserted in the same direction as the board hole 111 (regardless of the positive or negative direction). The dial hole 212 is provided in the dial 60 so that the dial case positioning pin 213 is inserted in the same direction as the board hole 111 (regardless of the positive or negative direction). Also, the dial hole 212 is provided at a position that coincides with the dial hole 211 in the front-rear direction. The dial case positioning pin 213 is provided in the middle case 205 and is inserted into the dial hole 211 and dial hole 212 to position the dial 106 and dial 60 with respect to the middle case 205 .

The display device 1 shown in FIG. can be reduced. As a result, the display device 1 can reduce the positional deviation of the design 107 of the dial 106 with respect to the light guide 104 and maintain the light guide efficiency of the light guide 104 . That is, the display device 1 can illuminate the design 107 with the designed brightness.

Note that the dial hole 211 or the dial hole 212 may be omitted in the display device 1 shown in FIG. Even if either one of the dial hole 211 and the dial hole 212 is fixed by the dial case positioning pin 213, positional deviation with respect to the light source 103 and the light guide 104 can be reduced.

In addition, in the display device 1, the first positioning portions 80 and 110 are formed by holes provided in one of the circuit board 30 and the middle cases 51 and 205 and positioning holes provided in the other of the circuit board 30 and the middle cases 51 and 205. A pin is fine. The second positioning portions 90 and 120 are formed by holes provided in one of the inner cases 51 and 205 and the light guides 40 and 104 and positioning holes provided in the other of the inner cases 51 and 205 and the light guides 40 and 104. A pin is fine. Further, the third positioning portion 210 may be a hole provided in one of the middle case 205 and the dial 106 (the dial 60) and a positioning pin provided in the other of the middle case 205 and the dial 106 (the dial 60). Just do it. That is, the relationship between the holes of the first positioning portions 80, 110, the second positioning portions 90, 120, and the third positioning portion 210 and the positioning pins is not limited to the above-described embodiments and modifications of the display device.

1 Display device 2 Speedometer 3 Engine tachometer 10 Pointer 11 Light-emitting part 12 Cap 13 Sheath part 14 Side part 15 Peripheral edges 20, 25, 106 Dial plate 20a Dial front surface 20b Dial rear surface 21, 107 Design 23 Decoration ring 30 Circuit Substrate 31 pointer driving portions 32, 103 light source 35 pointer shafts 40, 104 light guides 41, 105 light receiving surface 50 case 51, 205 middle case 52 outer case 60 dial 62 cover 63 dial peripheral edges 80, 110 first positioning portion 81, 111 board hole 82 case positioning pin 85 first detent 86 board detent hole 87 case detent pin 90, 120 second positioning portion 91 case hole 92 light guide positioning pin 95 second detent 96 case detent Hole 97 Light guide detent pin 102 Display panel 112 Circuit board case positioning pin 121 Light guide hole 122 Light guide case positioning pin 210 Third positioning portion 211 Dial hole 212 Dial hole 213 Dial case positioning Pins X1, X2 Arrows Z1, Z2, Z3, Z4 Axis

Claims (5)

a circuit board having a light source;
a light guide that guides the light from the light source to an illumination object;
a case that supports the circuit board and the light guide;
a first positioning portion that positions the case with respect to the circuit board;
a second positioning portion that positions the light guide with respect to the case and is provided at a position facing the first positioning portion with respect to the light source ;
The case expands or contracts with the first positioning portion as a starting point during thermal expansion or thermal contraction,
The display device, wherein the light guide expands or contracts with the second positioning portion as a starting point when thermally expanding or contracting . the first positioning portion is a hole provided in one of the circuit board and the case, and a positioning pin provided in the other of the circuit board and the case;
2. The display device according to claim 1 , wherein the second positioning portion is a hole provided in one of the case and the light guide and a positioning pin provided in the other of the case and the light guide. the first positioning portion includes a board hole provided in the circuit board and a case positioning pin inserted into the board hole provided in the case;
3. The display device according to claim 2 , wherein said second positioning portion is a case hole provided in said case and a light guide positioning pin inserted into said case hole provided in said light guide. a pointer driving unit provided on the circuit board and having a pointer shaft extending vertically from the circuit board to the front side;
a pointer that is connected to the pointer shaft, rotates to point to the index, and is illuminated by the light from the light source;
4. The display device according to any one of claims 1 to 3 , wherein said light source is provided around said pointer driving section, and said light guide body guides the light of said light source to said pointer. 4. The device according to any one of claims 1 to 3 , further comprising a dial that is provided on the front side of the light source and displays a design by transmitting the light of the light source, and the light guide guides the light of the light source to the design. The display device according to any one of claims 1 to 3.

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