JP2019168377A - Display unit - Google Patents

Abstract

To provide a display unit that can achieve both visibility and light guide efficiency.SOLUTION: A display unit comprises: a light source that emits light; a dial that is provided on the front side of the light source and transmits the light to display a design; and a light guide body 16 that is arranged on the back side of the dial, guides the light to the dial, and has a front face and a back face 16a. The back face 16a has concave parts 45 that reflect the light incident on the back face 16a and inside the light guide body 16 toward the front face side, and flat parts 46 that are located between the concave parts 45 and connected with the concave parts 45 in a curved manner at the boundaries 49 with the concave parts 45.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a display device mounted on a vehicle or the like.

  A vehicle such as an automobile is equipped with a display device that displays information necessary for driving such as a speedometer and an engine speed meter. Such a display device has a dial plate having designs such as scales, numbers, characters, symbols and the like formed in a letter shape. The dial plate transmits the light of the light source provided on the back side through the light guide, thereby displaying the design or making it stand out by illuminating it. In order to make the design visible well, a plurality of minute recesses are formed on the back surface of the light guide.

JP 2010-190599 A

  While the minute recess can make the design visible well, the light in the light guide incident on the boundary between the back surface of the light guide and the recess is guided without being reflected in the light guide. It will be emitted outside the body. For this reason, the minute recess is required to achieve both improved visibility and improved light guide efficiency.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a display device that can achieve both visibility and light guide efficiency.

  In order to solve the above-described problems, a display device according to the present invention includes a light source that emits light, a dial plate that is provided on the front side of the light source and displays a design by transmitting the light, and the dial plate A light guide that is arranged on the back side of the light guide and guides the light to the dial and has a front surface and a back surface, and the back surface transmits the light in the light guide that is incident on the back surface to the front surface. And a flat part located between the concave parts and connected to the concave part at a boundary with the concave part.

  In the display device according to the present invention, both visibility and light guide efficiency can be achieved.

The front view which shows embodiment of the display apparatus which concerns on this invention. Sectional drawing which follows the II-II line | wire of FIG. The expanded sectional view of the light guide back. The expanded sectional view of the light guide back of the light guide as a comparative example.

  Embodiments 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 on a vehicle such as an automobile or a motorcycle, a ship, an agricultural machine, or a construction machine.

  FIG. 1 is a front view showing a display device 1 which is an embodiment of a display device according to the present invention.

  2 is a cross-sectional view taken along line II-II in FIG.

  In the following description, the “front side” means the near side in FIG. 1 and the upper side in FIG. 2 and FIG. 3 (the dial 12 side) and the side that is visible to the viewer (driver). “Back side” means the back side in FIG. 1 and the lower side in FIG. 2 and FIG. 3 (circuit board 15 side).

  The display device 1 includes a speedometer 2 and an engine speed meter 3. The speedometer 2 is a pointer-type (mechanical) meter that displays the speed of the vehicle. The engine speed meter 3 is a pointer-type meter that displays the engine speed of the vehicle.

  The display device 1 mainly includes a pointer 11, a dial plate 12, a facing plate 14, a circuit board 15, a light guide 16, and an intermediate case 50.

  The pointer 11 is connected to a pointer shaft of a pointer driving unit provided on the circuit board 15, and rotates on a surface parallel to the dial 12 on the front side of the dial 12. The pointer 11 indicates a design 21 such as a scale or a number formed on the dial 12 corresponding to the speed or the engine speed according to the speed of the vehicle or the engine speed.

  The dial 12 is a thin plate-like member provided on the front side of the light source 31 and the back side of the pointer 11. The dial 12 has a base material and a light shielding layer.

  The base material of the dial 12 is, for example, a transparent polycarbonate resin and is a plate-like member having transparency (translucency).

  The light shielding layer is a printed layer printed with a black light shielding ink formed on the front side (or back side) of the substrate. The light shielding layer has a blank portion corresponding to the shape of the design 21. The design 21 is a scale or number indicated by letters, symbols, and pointers 11. The dial 12 displays the design 21 by lighting through the light from the light source 31.

  The facing plate 14 covers the front surface of the dial 12 and shields unnecessary areas on the dial 12. The facing plate 14 has an opening window 14 a that defines (exposes) display areas of the speedometer 2 and the engine speed meter 3. The facing plate 14 is fitted with a cover (not shown) made of, for example, translucent polycarbonate resin or inorganic glass on the front side, and a lower case (not shown) made of, for example, black synthetic resin on the back side. By fitting, the housing of the display device 1 is formed.

  The circuit board 15 mainly includes a pointer driving unit, a light source 31, and a control unit including a driver of the light source 31, the pointer driving unit, and the like.

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

  The light source 31 is provided on the front surface of the circuit board 15 and emits light. The light source 31 is, for example, a top view type (upside light emission type) LED (Light Emitting Diode). The light sources 31 are provided according to the number and positions of the designs 21 of the display device 1.

  The light guide 16 is made of a transparent resin such as polymethyl methacrylate (PMMA). The light guide 16 is arranged on the dial back 12 a side and guides the light from the light source 31 to the dial 12. The light guide 16 has a light incident part 41 and a main body part 42.

  The light incident part 41 is a piece projecting substantially perpendicularly to the main body part 42 from two end parts of the main body part 42, and has an incident surface 41 a facing the light source 31 (circuit board 15) at the end part. ing. The light incident portion 41 guides light emitted from the light source 31 to the main body portion 42.

  As shown in FIG. 1, the main body 42 is an arc-shaped disc in which a part of a circle having an outer diameter and an inner diameter is cut out, and is disposed so as to face the design 21. And a light guide body front surface 16b. The light guide back surface 16a is a reflection surface, and repeatedly reflects the light incident from the incident surface 41a and guides it to the light guide front surface 16b. The light guide back surface 16 a faces the wall surface 52 of the light shielding wall 51 of the middle case 50. The light guide front surface 16b is an emission surface, and mainly emits light reflected by the light guide rear surface 16a toward the dial plate 12. The light guide front surface 16 b faces the dial back surface 12 a (design 21) of the dial 12.

  Here, FIG. 3 is an enlarged cross-sectional view of the light guide back surface 16a.

  The light guide back surface 16 a (reflection surface) has a recess 45. The recess 45 reflects light incident on the light guide back surface 16a to the light guide front surface 16b side. The concave portions 45 have, for example, a conical shape with a diameter of about 60 μm on the bottom surface, and are arranged at regular intervals. For this reason, the light guide back surface 16 a has a flat portion 46 located between the recesses 45 and connected to the periphery of the recess 45. The flat portion 46 is connected to the concave portion 45 in a curved manner. That is, the extension line of the flat part 46 and the conical generatrix 48 of the concave part 45 intersects to form a predetermined angle (45 degrees in FIG. 3), but the boundary 49 has no angle and is curved ( (Draw an arc)

  The curvature of the boundary 49 varies the luminance of the light emitted from the light guide front surface 16b. That is, the greater the curvature, the better the reflection efficiency and the greater the brightness. For this reason, the light guide 16 varies the curvature of the boundary 49 according to the distance from the light source 31. That is, the curvature of the boundary 49 was increased as the distance from the light source 31 was increased. Thereby, the brightness | luminance of the design 21 in the dial 12 can be made uniform.

  According to the inventor's knowledge, a radius of curvature that is too small has little effect, and it is preferable that one quarter or more of the length of the side surface of the cone (bus 48) is formed by an arc. .

  In addition, light incident from the two light incident portions 41 intersects at an intermediate point (a position where the distance from the light source 31 is the largest) 42 a between the two light incident portions 41 of the main body portion 42. Since the light from two directions intersects and the luminance increases at the intermediate point 42a, the curvature of the boundary 49 of the recess 45 is made smaller than the largest curvature. Thereby, the brightness | luminance of the design 21 in the dial 12 can be made uniform.

  The middle case 50 is made of a synthetic resin such as white, and fixes or supports the dial plate 12, the circuit board 15, and the light guide 16. As shown in FIG. 2, the middle case 50 includes a light shielding wall 51 that surrounds the light source 31 and guides light. The light shielding wall 51 forms a cylindrical space with a wall that divides an illumination (light emission) region of the light source 31, and light passes through the cylindrical space. One end of the light shielding wall 51 (the end surface of the light shielding wall 51 facing the circuit board 15) is in contact with the circuit board 15, and the other end (the end surface of the light shielding wall 51 facing the dial plate 12) is in contact with the dial plate rear surface 12a. Yes.

  In such a display device 1, the concave portion 45 provided on the light guide back surface 16 a and the flat portion 46 are connected in a curved manner. Thereby, the light guide efficiency of the light guide 16 can be improved.

  Here, FIG. 4 is an enlarged cross-sectional view of the light guide back surface 100a of the light guide 100 as a comparative example.

  In the light guide 100, the concave portion 145 and the flat portion 146 are connected not at a curve but at an angle (for example, 45 degrees) as in the light guide 16 in the present embodiment. In such a light guide 100, when light toward the light guide back surface 100a in the light guide 100 enters the boundary 149, the light guide 100 is emitted from the light guide back surface 100a without being reflected. The emitted light is reflected by the middle case and enters the light guide 100 again. However, there is a considerable loss in the amount of light reaching the design.

  On the other hand, the light guide 16 in this embodiment connected the recessed part 45 and the flat part 46 in a curve. For this reason, light incident on the boundary 49 is reflected at the curved boundary 49. Therefore, the light guide 16 can exhibit the effect of the recessed part 45 and can improve visibility, without reducing light guide efficiency.

  Although several embodiments of the present invention have been described, these embodiments are 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 changes 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 invention described in the claims and the equivalents thereof.

  For example, the recess 45 is not limited to a conical shape, and may be a quadrangular pyramid shape or a triangular pyramid shape. Moreover, the recessed part 45 may be formed not in dot shape but in a groove shape longer than dots.

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Speedometer 3 Engine speed meter 11 Pointer 12 Dial 12a Dial back surface 14 Look-back plate 14a Opening window 15 Circuit board 16 Light guide 16a Light guide back 16b Light guide front 21 Design 31 Light source 41 Incident light Part 41a Incident surface 42 Body part 42a Intermediate point 45 Recess 46 Flat part 48 Bus line 49 Boundary 50 Middle case 51 Light shielding wall 52 Wall surface 100 Light guide 100a Light guide back surface 145 Recess 146 Flat part 149 Boundary

Claims (3)

A light source that emits light;
A dial that is provided on the front side of the light source and displays a design by transmitting the light;
A light guide disposed on the back side of the dial for guiding the light to the dial and having a front surface and a back surface;
The back surface includes a recess that reflects the light in the light guide incident on the back surface toward the front surface, and a flat portion that is located between the recesses and is connected to the recess in a curved line at a boundary between the recess and the recess. And a display device. The display device according to claim 1, wherein the light guide has a larger curvature at the boundary as the distance to the light source increases. The display device according to claim 1, wherein the recess has a conical shape, a quadrangular pyramid shape, or a triangular pyramid shape.

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