CN215219371U - Planar lighting device - Google Patents

Abstract

The utility model aims to provide a surface-shaped lighting device which can utilize an elastic component, help to narrow a frame and can easily design a gap. The planar lighting device of the embodiment includes a light guide plate, a light source, a frame, and an elastic member. The light guide plate is used for guiding light from the light incident side. The light source irradiates light to the light incident side. The frame accommodates the light guide plate and the light source. The elastic member is partially accommodated in a side wall of the frame facing a terminal surface of the light guide plate on the side opposite to the light incident side surface, and presses the terminal surface. The elastic member includes a beam portion extending in the longitudinal direction of the side wall, and a projection extending from the approximate center of the beam portion toward the light guide plate side. The beam portion is held at both ends thereof inside the side wall so as to be deformable to a side opposite to an extending direction of the convex portion.

Description

Planar lighting device

Technical Field

The utility model relates to a surface form lighting device.

Background

A so-called edge-light type planar lighting device is known in which light is incident from a light incident side surface of a light guide plate and light is emitted from one main surface of the light guide plate (see, for example, patent document 1). Such a planar lighting device is used as a backlight or the like in a liquid crystal display device for a vehicle.

In order to stabilize optical characteristics, the Light guide plate needs to stably maintain a distance between a Light source such as an LED (Light Emitting Diode) and a Light incident side surface, and is essential to stably maintain the Light guide plate so as not to be loosened by vibration or the like. In this regard, since the light guide plate made of resin or the like has a linear expansion coefficient larger than that of a material such as metal constituting the housing, the light incident side surface is often urged toward the light source side and held by an elastic member such as rubber disposed in a gap portion outside the three side surfaces other than the light incident side surface so that expansion and contraction of the light guide plate due to temperature change can be absorbed (see, for example, patent document 1). When an elastic member such as rubber is used, it is preferable because stable holding of the light guide plate can be easily performed.

In general, in a planar lighting device, a top frame provided with an opening for light emission is often used as a part of a housing, and a portion of the top frame where the opening for light emission is formed is called a bezel. Recently, a narrow bezel is required to narrow the width of the bezel mainly from the viewpoint of design.

Patent document 1: japanese laid-open patent publication No. 2012 and 216528

However, in the configuration in which the elastic member such as rubber is disposed in the gap portion outside the three side surfaces other than the light incident side surface of the light guide plate, the bezel portion cannot be narrowed in view of the space required for disposing the elastic member, and it is difficult to achieve a narrowed bezel.

In the case of using an elastic member such as rubber, when the elastic member is formed to have an excessively large size with respect to the gap so as to be easily crushed and inserted at the time of assembly at normal temperature, the amount of contraction of the light guide plate at the lowest temperature of the standards for the elongation compensation of the elastic member may not be allowed to pass, and the necessary pressing force may not be maintained. Conversely, when the size of the elastic member is large relative to the gap, assembly at normal temperature becomes difficult, and as the maximum temperature on the specification is approached, the elastic member exceeds the compression limit and breaks due to the light guide plate, and deforms in the thickness direction to wrinkle the optical sheet, thereby deteriorating the optical characteristics. That is, it is difficult to design a gap including a gap and a size of the elastic member so as to maintain a necessary pressing force to the light guide plate in a predetermined temperature range and not to cause abnormal deformation of the elastic member.

SUMMERY OF THE UTILITY MODEL

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a planar lighting device which can contribute to a narrow frame while using an elastic member, and can easily perform a gap design.

In order to solve the above-described problems and achieve the object, a planar lighting device according to an aspect of the present invention includes a light guide plate, a light source, a frame, and an elastic member. The light guide plate is used for guiding light from the light incident side. The light source irradiates light to the light incident side. The frame accommodates the light guide plate and the light source. The elastic member is partially accommodated in a side wall of the frame facing a terminal surface of the light guide plate on the side opposite to the light incident side surface, and presses the terminal surface. The elastic member includes a beam portion extending in the longitudinal direction of the side wall, and a projection extending from the approximate center of the beam portion toward the light guide plate side. The beam portion is held at both ends thereof inside the side wall so as to be deformable to a side opposite to an extending direction of the convex portion.

The planar lighting device according to one aspect of the present invention can contribute to narrowing the frame while using the elastic member, and can easily perform the gap design.

Drawings

Fig. 1 is an external perspective view of a planar lighting device according to an embodiment.

Fig. 2 is an X-X end view of the planar illumination device in fig. 1.

Fig. 3 is a plan view showing a bottom end frame, a light guide plate, and an optical sheet of the planar lighting device.

Fig. 4A is an enlarged view of the region R1 of fig. 3 at normal temperature.

Fig. 4B is an enlarged view at the lowest temperature on the scale of the region R1 of fig. 3.

Fig. 4C is an enlarged view at the highest temperature on the scale of the region R1 of fig. 3.

Fig. 5 is an enlarged view of the region R2 of fig. 3.

Fig. 6A is an enlarged view of the vicinity of the elastic member of the planar lighting device of the comparative example at room temperature.

Fig. 6B is an enlarged view of the planar lighting device of the comparative example at the lowest temperature in the specification in the vicinity of the elastic member.

Fig. 6C is an enlarged view of the planar lighting device of the comparative example at the highest temperature in the specification in the vicinity of the elastic member.

Description of reference numerals:

a planar lighting device; a bottom end frame; a groove; 2b2, 2b3... open; a top frame; an emitting surface; a reflective sheet; 6.. a light guide plate; 7-9. A substrate; a light source; a pin; an elastic member; a beam section; convex part 13b

Detailed Description

The planar lighting device according to the embodiment will be described below with reference to the drawings. Further, the present invention is not limited to the embodiment. In addition, the relationship of the sizes of the elements and the ratios of the elements in the drawings may be different from the actual ones. In some cases, the drawings include portions having different dimensional relationships and ratios from each other. In principle, the contents described in one embodiment and modification are also applicable to other embodiments and modifications.

Fig. 1 is an external perspective view of a planar lighting device 1 according to an embodiment. In fig. 1, for convenience of explanation, a left-right direction (a longitudinal direction of the planar illumination device 1) is set as an X-axis direction, a depth direction (a short-side direction of the planar illumination device 1) is set as a Y-axis direction, and a vertical direction (a thickness direction of the planar illumination device 1) is set as a Z-axis direction. The longitudinal direction and the short-side direction of the planar lighting device 1 may be opposite to each other.

In fig. 1, a planar lighting device 1 has a substantially rectangular (or substantially square) and substantially plate-like outer shape, and is configured as a housing by a bottomed box-shaped bottom frame 2 that houses a light guide plate or the like described later, and a top frame 3 that covers an opening side of the bottom frame 2. The top frame 3 is provided with an emission surface 4 through a substantially rectangular opening 3a, and emits light from the inside of the planar lighting device 1 to the outside. The bottom end frame 2 and the top frame 3 are formed by die casting, a metal plate, or the like. When the planar lighting device 1 is used as a backlight of a navigation device, an indicator, or the like for a vehicle, a liquid crystal display device or the like is attached to the emitting surface 4 side.

Fig. 2 is an X-X end view of the planar lighting device 1 in fig. 1. In fig. 2, the bottom end frame 2 has a bottom 2a and side walls 2b surrounding four sides of the periphery of the bottom 2 a. The reflective sheet 5, the light guide plate 6, and the optical sheets 7, 8, and 9 are stacked in this order on the bottom portion 2a of the bottom chassis 2.

The reflective sheet 5 is a reflective sheet for reflecting light leaking from the light guide plate 6 to the bottom portion 2a side and returning it to the light guide plate 6. When the inner surface of the bottom portion 2a of the bottom end frame 2 is coated with white paint or the like to have good reflection characteristics, the reflection sheet 5 may be omitted.

The light guide plate 6 is made of a transparent resin such as polycarbonate or acrylic, guides light incident from the light incident side surface 6a, which is one side surface, to the entire surface, and emits the light from one main surface (an upper main surface in the drawing). A recess 6c is provided at a substantially center in the longitudinal direction of the light incident side end of the light guide plate 6, and a shaft portion of a pin 12 screwed from the outside of the bottom portion 2a is inserted into the recess 6 c. The details will be described later.

The optical sheet 7 is, for example, a diffusion sheet. The optical sheet 8 is, for example, a prism sheet. The optical sheet 9 is, for example, a Brightness Enhancement Film (DBEF). The number of optical sheets arranged on the light-emitting surface side of the light guide plate 6 is not limited to three.

A predetermined gap (slit) is formed between the end portions of the light guide plate 6 and the optical sheets 7, 8, and 9 on the non-incident light side and the side wall 2b of the bezel 2 to allow expansion and contraction of the light guide plate 6 and the optical sheets 7, 8, and 9 due to a temperature change. Further, one end of an elastic member 13 made of rubber or the like, which is partially accommodated in the side wall 2b of the base end frame 2, abuts on the end surface 6b of the light guide plate 6 on the side opposite to the light incident side surface 6a, and presses the light guide plate 6 to the light incident side. The details will be described later.

On the other hand, as a structure of the light incident side of the light guide plate 6, a substrate 10 is fixed to the light incident side wall 2b of the bezel frame 2, a plurality of light sources 11 made of LEDs or the like are arranged in a row on the substrate 10, for example, and the light emitting surface of the light source 11 faces the light incident side surface 6a of the light guide plate 6. In addition, although the light source 11 is illustrated as being configured by an LED or the like of a Top view type (Top view type) (a type that emits light from the Top surface), an LED or the like of a Side view type (Side view type) that emits light from the Side surface may be used as the light source 11 instead of the Top view type. In this case, the surface of the substrate 10 is arranged perpendicular to the light incident side surface 6a of the light guide plate 6.

Fig. 3 is a plan view showing the bottom frame 2, the light guide plate 6, and the optical sheets 7 to 9 of the planar lighting device 1. The elastic member 13 shown in fig. 2 is disposed in, for example, three regions R1 in the side wall 2b on the non-light-incident side of the bezel 2. The pin 12 shown in fig. 2 is disposed in the light entrance side region R2.

Fig. 4A is an enlarged view of the region R1 of fig. 3 at normal temperature. The normal temperature is, for example, 25 ℃.

In fig. 4A, a substantially rectangular groove 2b1 is provided in the side wall 2b, an opening 2b2 is provided on the light guide plate 6 side of the groove 2b1, and an opening 2b3 is provided on the opposite side. Further, a substantially T-shaped elastic member 13 is provided along the inner surfaces of the groove 2b1 and the opening 2b 2. The elastic member 13 includes a beam portion 13a extending in the longitudinal direction of the side wall 2b, and a projection portion 13b extending from the substantial center of the beam portion 13a toward the light guide plate 6. Both ends of the beam portion 13a in the longitudinal direction are held by portions of the groove 2b1 other than the openings 2b2 and 2b3, and the beam portion 13a of the elastic member 13 can be deformed to the opposite side to the extending direction of the convex portion 13b by the presence of the opening 2b3. The front end surface of the projection 13b presses the end surface 6b of the light guide plate 6.

In fig. 4A, at normal temperature, the end surface 6b of the light guide plate 6 is located at the position of the line L1, and the elastic member 13 is loaded in a state compressed to some extent in the light guiding direction (vertical direction in the drawing), and presses the end surface 6b of the light guide plate 6 toward the light incident side. In general, assembly is performed at normal temperature, and when the elastic member 13 is set to a long size in the light guiding direction in consideration of an extension margin at low temperature, it is difficult to crush and insert the elastic member. However, since the elastic member 13 can be deformed outward and inserted by the presence of the opening 2b3, even the elastic member 13 having a long dimension in the light guiding direction can be easily inserted, and the pressing force can be maintained at the minimum temperature in the specification.

The pressing force F applied from the elastic member 13 to the light guide plate 6 is a vector sum of the elastic force F1 of the elastic member 13 itself and the escape force F2 due to the opening 2b3, and the escape force F2 is substantially proportional to a value obtained by dividing the width W2 of the opening 2b3 by the width W1 of the opening 2b 2. That is, the larger the width W2 of the opening 2b3 is, the more easily the elastic member 13 deforms outward, so the larger the escape force F2 is, the larger the width W1 of the opening 2b2 is, the higher the proportion of the elastic member 13 itself that contributes to the elastic force F1 is, and the smaller the escape force F2 is. Therefore, the pressing force F applied to the light guide plate 6 can be appropriately adjusted by adjusting the widths W1 and W2 of the openings 2b2 and 2b3 in addition to adjusting the material (for example, hardness) and size of the elastic member 13.

Fig. 4B is an enlarged view at the lowest temperature on the scale of the region R1 of fig. 3. The minimum temperature in the specification is set to, for example, -40 ℃. In fig. 4B, the light guide plate 6 contracts due to the temperature decrease, and the end surface 6B of the light guide plate 6 is retracted toward the light incident side by the pressing force of the elastic member 13 to be at the position of the line L2. For example, the elastic member 13 can be designed to be fully extended to lose the pressing force at the minimum temperature in the specification, and to maintain the pressing force at a temperature higher than the minimum temperature.

Fig. 4C is an enlarged view at the highest temperature on the scale of the region R1 of fig. 3. The maximum temperature in the specification is, for example, 85 ℃. In fig. 4C, the light guide plate 6 expands due to the temperature rise, and the end surface 6b of the light guide plate 6 is located at the line L3. At this time, when the elastic member 13 tends to break beyond the compression limit, the beam portion 13a of the elastic member 13 is deformed toward the outside like the curve L4 due to the presence of the opening 2b3 of the side wall 2b, preventing deformation in the thickness direction. Therefore, wrinkles do not occur in the optical sheets 7 to 9 stacked on the light guide plate 6, and deterioration of optical characteristics can be prevented.

Fig. 4B shows a specific example of the dimensions in the embodiment. In this example, the thickness from the outer surface of the side wall 2b to the groove 2b1 is 0.5mm, the thickness from the inner surface of the side wall 2b to the groove 2b1 is 0.5mm, the width of the groove 2b1 in the light guiding direction is 1.0mm, the width of the side wall 2b from the inner surface to the terminal surface 6b of the light guide plate 6 at normal temperature is 0.325mm, the width of the terminal surface 6b to the terminal surface 6b at the lowest temperature in the specification is 0.368mm, and the width of the terminal surface 6b at normal temperature to the opening 3a of the top frame 3 in the light guiding direction (frame width) is 0.468mm, whereby the width of the side wall 2b from the outer surface to the opening 3a in the light guiding direction (frame width) is 2.793 mm. The width of 0.468mm in the light guiding direction from the end surface 6B at normal temperature to the opening 3a of the top frame 3 is equal to or less than half of the corresponding width "1.168 mm" in the comparative example (fig. 6B) described later. The reason for this is that it is not necessary to provide the optical sheets 7 to 9 with notches, which will be described later, in correspondence with the elastic members 13. When the notch is present, the brightness in the vicinity thereof becomes uneven, and therefore the ineffective area needs to be increased.

Fig. 5 is an enlarged view of the region R2 of fig. 3. In fig. 5, a substantially rectangular recess 6c is provided at substantially the center in the longitudinal direction of the light incident side end of the light guide plate 6, and the shaft of the pin 12 fixed to the bezel 2 is inserted into the recess 6 c.

Fig. 6A is an enlarged view of the vicinity of the elastic member 13 'of the planar lighting device 1' of the comparative example at room temperature. Fig. 6A shows an enlarged view of the planar lighting device 1' at the same position as the region R1 in fig. 3. As the normal temperature, for example, 25 ℃ is set as in the embodiment.

In fig. 6A, the side wall 2b ' is a flat wall, and an elastic member 13 ' made of substantially rectangular rubber or the like is inserted into a gap portion between the side wall and the light guide plate 6 '. Further, substantially rectangular cutouts 7a ' to 9a ' are provided in portions of the optical sheets 7 ' to 9 ' close to the elastic member 13 '. This is to prevent wrinkles from occurring in the optical sheets 7 ' to 9 ' when the elastic member 13 ' is broken and deformed in the thickness direction.

In fig. 6A, at normal temperature, the end surface of the light guide plate 6 'is located at the line L1', and the elastic member 13 'is loaded in a state compressed to some extent in the light guiding direction (vertical direction in the drawing), and presses the end surface of the light guide plate 6' toward the light entrance side. In general, assembly is performed at normal temperature, and when the elastic member 13' is set to a large size in consideration of an extension margin at low temperature, it is difficult to crush and insert the elastic member.

Fig. 6B is an enlarged view of the planar lighting device 1 'of the comparative example at the lowest temperature in the vicinity of the elastic member 13' in the specification. The minimum temperature in the specification is, for example, -40 ℃ as in the embodiment. In fig. 6B, the light guide plate 6 'contracts due to the temperature decrease, and the end surface of the light guide plate 6' is retracted toward the light entrance side by the pressing force of the elastic member 13 'to be at the position of the line L2'.

Fig. 6C is an enlarged view of the planar lighting device 1 'of the comparative example at the highest temperature in the vicinity of the elastic member 13' in the specification. The maximum temperature in the specification is, for example, 85 ℃ as in the embodiment. In fig. 6C, the light guide plate 6 ' expands due to the temperature rise, and the end surface of the light guide plate 6 ' is located at the line L3 '.

Fig. 6B shows a specific example of the dimensions in the comparative example. In this example, the thickness of the side wall 2b ' in the light guiding direction is 1.0mm, the width of the light guiding direction from the inner surface of the side wall 2b ' to the end surface of the light guide plate 6 ' at normal temperature is 0.8mm, the width of the light guiding direction from the end surface to the end surface at the lowest temperature in the specification is 0.4mm, and the width of the light guiding direction from the end surface at normal temperature to the opening 3a ' of the top frame 3 ' (corresponding to the opening 3a of the top frame 3 in the embodiment) is 1.168mm, so that the width of the light guiding direction (frame width) from the outer surface of the side wall 2b ' to the opening 3a ' is 2.968 mm.

As is clear from comparison between fig. 4A to 4C showing the embodiment and fig. 6A to 6C showing the comparative example, although an elastic member such as rubber is used in the embodiment, a part of the elastic member 13 is accommodated in the side wall 2b of the bezel 2, and is deformed outward from the opening 2b3 when compressed by thermal expansion of the light guide plate 6. Therefore, the occurrence of wrinkles in the optical sheets 7 to 9, which has been a problem in the conventional technology, is suppressed. This narrows the non-effective region in which the optical characteristics are not uniform, and further, the frame of the planar lighting device can be narrowed.

In addition, in the embodiment, even if the elastic member having a large size in the light guiding direction is used in order to maintain the pressing force to the minimum temperature in the specification, since the elastic member can be inserted by being deformed backward through the opening 2b3, the assembly becomes easy. In addition, even at the highest temperature in the specification, since the breakage of the elastic member 13 can be absorbed in the bottom end frame 2 by the backward deformation through the opening 2b3, the elastic member 13 can be prevented from being deformed in the thickness direction, and the deterioration of the optical characteristics due to the wrinkles can be prevented even without providing the cuts in the optical sheets 7 to 9. This improves the degree of freedom in design, and facilitates the design of a gap including a gap and the size of the elastic member for maintaining a required pressing force to the light guide plate 6 in a predetermined temperature range and preventing abnormal deformation of the elastic member.

Further, by adjusting the mechanical properties of the elastic member 13 and the widths W1 and W2 of the openings 2b2 and 2b3 of the side wall 2b, the amount of deformation of the elastic member 13 and the pressing force against the light guide plate 6 can be adjusted, and appropriate design can be easily performed. Further, by providing a plurality of portions on the end side of the bottom chassis 2 where the elastic member 13 is provided, a necessary pressing force against the light guide plate 6 can be obtained.

As shown in fig. 2 and 5, the pin 12 provided on the bottom end frame 2 is inserted into the recess 6c of the light guide plate 6, whereby the center portion of the light incident side surface 6a of the light guide plate 6 is positioned, and it is not necessary to dispose an elastic member or the like for support at both ends in the direction orthogonal to the light guide direction, which can contribute to narrowing the bezel in this direction.

While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit and scope of the invention.

As described above, the planar lighting device according to the embodiment includes: a light guide plate for guiding light from the light incident side; a light source that irradiates light to the incident light side; a frame, a light guide plate accommodating and a light source; and an elastic member, a part of which is accommodated inside a side wall of the frame facing a terminal surface of the light guide plate opposite to the light incident side surface, the elastic member pressing the terminal surface, the elastic member having a beam portion extending in a longitudinal direction of the side wall, and a convex portion extending from a substantial center of the beam portion toward the light guide plate side, both ends of the beam portion being held inside the side wall so that the beam portion is deformable to a side opposite to an extending direction of the convex portion. This can contribute to narrowing the bezel while using the elastic member, and can facilitate the gap design.

That is, by housing a part of the elastic member inside the side wall of the frame, it is possible to contribute to narrowing the bezel. In addition, even an elastic member having a large size in the light guiding direction can be inserted by the backward deformation, so that the assembly is easy, and the pressing force can be maintained at the minimum temperature in the specification. Further, even at the highest temperature in the specification, by absorbing the breakage of the elastic member in the frame by the backward deformation, the elastic member can be prevented from being deformed in the thickness direction of the planar lighting device, and deterioration of the optical characteristics due to the wrinkle of the optical sheet can be prevented. This improves the degree of freedom in design, and facilitates the gap design.

In addition, the side wall includes: a groove for accommodating the beam portion and extending in the longitudinal direction of the side wall; a first opening provided on the terminal surface side of the groove and through which the projection is inserted; and a second opening provided on an opposite side of the groove from the first opening, allowing deformation of the beam portion. Thus, both ends of the beam portion of the elastic member are held so that the beam portion of the elastic member can be deformed in the direction opposite to the extending direction of the convex portion, and the amount of deformation of the elastic member and the pressing force against the light guide plate can be adjusted by adjusting the sizes of the first opening and the second opening.

The elastic member is provided in plurality on one side of the frame facing the terminal surface. Thus, the required pressing force on the light guide plate can be obtained by adjusting the number of the elastic members.

In addition, a recess through which a pin provided in the frame is inserted is formed on the light incident side of the light guide plate. This makes it possible to fix the center position of the light incident side of the light guide plate, and to eliminate the need to dispose elastic members or the like for support at both ends of the light guide plate in the direction perpendicular to the light guiding direction, thereby contributing to a narrower bezel in that direction.

In addition, the elastic member is made of rubber. This makes it possible to stably hold the light guide plate with a simple structure.

The present invention is not limited to the above embodiment. Embodiments configured by appropriately combining the above-described respective components are also included in the present invention. Further, those skilled in the art can easily derive further effects and modifications. Therefore, the present invention is not limited to the above-described embodiments, and various modifications can be made.

Claims (8)

1. A planar lighting device is provided with:

a light guide plate for guiding light from the light incident side;

a light source that irradiates light to the light incident side surface;

a frame accommodating the light guide plate and the light source; and

an elastic member, a part of which is accommodated inside a side wall of the frame facing a terminal surface of the light guide plate on the opposite side of the light incident side surface, the elastic member pressing the terminal surface,

the elastic member has a beam portion extending in the longitudinal direction of the side wall and a projection extending from the substantial center of the beam portion toward the light guide plate side,

inside the side wall, both ends of the beam portion are held so that the beam portion can be deformed to the side opposite to the extending direction of the convex portion.

2. The planar lighting device according to claim 1,

the side wall is provided with:

a groove that accommodates the beam portion and extends in a longitudinal direction of the side wall;

a first opening provided on the terminal surface side of the groove and through which the projection is inserted; and

a second opening provided on an opposite side of the groove from the first opening, allowing deformation of the beam portion.

3. The planar lighting device according to claim 1 or 2,

the plurality of elastic members are provided on one side of the frame facing the terminal surface.

4. The planar lighting device according to claim 1 or 2,

a recess through which a pin provided in the frame is inserted is formed on the light incident side of the light guide plate.

5. The planar lighting device according to claim 3,

a recess through which a pin provided in the frame is inserted is formed on the light incident side of the light guide plate.

6. The planar lighting device according to claim 4,

the concave portion is formed in a central portion in a longitudinal direction of the light incident side surface of the light guide plate.

7. The planar lighting device according to claim 5,

the concave portion is formed in a central portion in a longitudinal direction of the light incident side surface of the light guide plate.

8. The planar lighting device according to claim 1 or 2,

the elastic member is made of rubber.

Images