JPH10247413A - Surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the leakage of light from a space between a light emitting module and a light guide plate by bonding a reflection tape onto a light outgoing face side and its opposite face side so as to hardly peel off. SOLUTION: A reflection tape 13 is flatly bonded between a light guide plate 2 top face (a light outgoing face 6) and the wiring board 8 upper end face of a light emitting module 5. A slope 22 is provided on the bottom face light incident side end portion of a light guide plate 2 bottom face so as to face a light incident face 3 slantingly downward. A reflection tape 14 is bonded onto the slope 22 of the light guide plate 2 bottom face so that the reflection tape 14 is caused to protrude obliquely toward the light emitting module 5 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a surface light source device. In particular, it relates to a surface light source device used for a liquid crystal display device or the like.

[0002]

2. Description of the Related Art FIG. 1 is an exploded perspective view showing a conventional surface light source device 1. A light guide plate 2 is made of a transparent resin material having a large refractive index, such as polycarbonate resin or methacrylic resin. One end surface of light guide plate 2 (light incident surface 3)
A plurality of recesses 4 each having a substantially arc shape are cut out, and
Each light source 10 of the light emitting module 5 is arranged so as to face. In addition, a diffusion pattern (not shown) is formed on the lower surface of the light guide plate 2 by unevenness processing, dot printing of diffuse reflection ink, or the like in order to make the luminance distribution on the upper surface (light emission surface 6) of the light guide plate 2 uniform. Have been. Further, on the lower surface side of the light guide plate 2, there is provided a reflection plate 7 for preventing light from leaking from a portion other than the light emission surface 6 to cause loss. The reflection plate 7 may be provided on the outer peripheral surface of the light guide plate 2 other than the light incident surface 3 in some cases.

The light emitting module 5 has a plurality of light sources 10 provided on a wiring board 8. Each light source 10 has a light emitting diode (LED) chip 10 a mounted on a wiring pattern 9 of the wiring board 8 and a transparent resin. 11 is sealed. For example, as shown in FIG. 2, the light emitting module 5 includes pocket portions 12 provided at both ends of the light incident surface 3 of the light guide plate 2.
The light guide plate 2 is arranged so as to face the light incident surface 3 by inserting both ends of the light guide plate 2.

[0004] When light R is emitted from the light emitting module 5 arranged to face the light incident surface 3 of the light guide plate 2, the light R emitted from the light source 10 is, as shown in FIG. The light enters the light guide plate 2 from the concave portion 4 of the light guide plate 3, spreads throughout the light guide plate 2 while repeating total reflection inside the light guide plate 2, and exits from the entire light exit surface 6 to the outside. Moreover, the light source 10
Is introduced into the light guide plate 2 from the recess 4,
When the light R enters the inside of the light guide plate 2 from the concave portion 4, the light R of the light source 10 spreads laterally as shown in FIG. 2, and only the front of the light source 10 becomes bright, causing uneven brightness on the light emitting surface 6. And the brightness distribution on the light exit surface 6 is made uniform.

[0005]

The light R is also emitted obliquely upward and downward from the light source 10 of the light emitting module 5, and the light R enters the light incident surface 3 of the light guide plate 2. If the light escapes from the space between the light emitting module 5 and the light guide plate 2 upward or downward without any change, the optical coupling efficiency between the light emitting module 5 and the light guide plate 2 decreases.

Therefore, conventionally, as shown in FIG. 3, a reflective tape 13 is attached between the light emitting surface 6 of the light guide plate 2 and the upper surface of the wiring board 8 of the light emitting module 5, and the light source 10 and the light guide plate Light is prevented from leaking upward from the space between the two.

However, since the height of the light emitting module 5 is about 1.5 times the thickness of the light guide plate 2, the lower part of the light emitting module 5 projects below the lower surface of the light guide plate 2 and It was difficult to attach a reflective tape between the lower surface of the light emitting module 2 and the light emitting module 5. Therefore, in general, no reflective tape is attached to the lower surface of the light emitting module 5, and about 60 to 70% of the light emitted downward leaks to the outside.

In the case where the reflection tape 14 is also adhered to the lower surface of the light emitting module 5, one end of the reflection tape 14 is adhered to the lower surface of the light guide plate 2 and the other is connected to the wiring of the light emitting module 5, as shown in FIG. The reflection tape 14 is bent at a large curvature because the reflection tape 14
Of the light guide plate 2 by the springback of
And the wiring board 8 easily peeled off or dropped off.

When the reflection tape 14 is peeled off, the reflection direction of the light R changes, so that the luminance distribution on the light exit surface 6 changes, and for example, the vicinity of the light source 10 sometimes becomes partially bright. . Also, the reflection tape 14
Usually, a metal tape is used.
If it falls off and falls on a circuit board or the like on which a signal processing circuit or the like is mounted, the circuit may be short-circuited and cause a failure.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to provide a light emitting module and a light guide in a surface light source device using a light emitting module having a light source mounted on a substrate. It is an object of the present invention to provide a structure for attaching a reflection tape for preventing light from leaking from a space between plates to a light emitting surface side and an opposite surface side so as not to be easily peeled off.

[0011]

A surface light source device according to a first aspect of the present invention comprises a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light source arranged to face the light incident surface of the light guide plate. In a surface light source device having a light emitting module mounted on a substrate, an inclined surface is provided at a light incident side end of the light guide plate on a light emission surface or a surface opposite to the light guide plate, and a reflection tape attached to the inclined surface Are projected from the light guide plate toward the light emitting module.

In the surface light source device according to the first aspect,
Since the reflective tape is stuck on the inclined surface of the light guide plate, the reflective tape can be disposed obliquely between the light emitting module and the light guide plate, avoiding the light source. The warpage of the tape can be reduced, and peeling and falling off of the reflective tape can be reduced.

According to a second aspect of the present invention, in the surface light source device according to the first aspect, a reflection tape is attached to the light guide plate only on the inclined surface.

Further, if the reflection tape is applied only to the inclined surface on the side of the light guide plate as in the embodiment of the second aspect, the reflection tape applied to the light guide plate is at the boundary between the inclined surface and the flat portion. And the risk of peeling or falling off of the reflective tape is further reduced.

According to a third aspect of the present invention, in the surface light source device of the first aspect, the inclined surface is partially provided along a light incident side end of the light guide plate. I have.

In the embodiment of the present invention, the inclined surface is provided in the light guide plate where the optical characteristics of the surface light source device are adversely affected by providing the inclined surface. For example, if a large inclined surface is provided at the position facing the light source, inconvenience may occur. In such a case, the inclined surface may not be provided at the position facing the light source.

According to a fourth aspect of the present invention, there is provided a surface light source device comprising: a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface; and a light source disposed opposite to the light incident surface of the light guide plate. In a surface light source device including a mounted light emitting module,
At the light emitting surface of the light guide plate or the opposite surface, a reflective tape is attached to the light incident side end of the light guide plate, and the reflective tape is projected from the light guide plate toward the light emitting module. The part is separated from the light emitting module.

In the surface light source device according to the fourth aspect,
Since the reflective tape is applied only to the light guide plate and the other end is suspended in the air, the reflective tape does not warp, and the risk of the reflective tape peeling off the light guide plate is reduced.

According to a fifth aspect of the present invention, in the surface light source device, a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light source disposed opposite to the light incident surface of the light guide plate are provided on the substrate. In a surface light source device including a mounted light emitting module,
On the light emitting surface of the light guide plate or the opposite surface, a reflective tape is attached to the light incident side end of the light guide plate, and the reflective tape is projected from the light guide plate toward the light emitting module, and the surface of the substrate on the light source mounting side The end provided on the light emitting module side of the reflection tape is attached to the projection provided on the light emitting module.

In the surface light source device according to the fifth aspect,
Since the projection is provided on the surface on the light source mounting side of the substrate, the reflection tape attached to the light emission surface of the light guide plate or the opposite surface thereof is attached to the projection of the substrate, so that the reflection tape is attached with a small warpage. And the reflection tape can be prevented from peeling or falling off.

According to a sixth aspect of the present invention, in the surface light source device, a light guide plate for introducing light from the light incident surface and extracting light from the light exit surface, and a light source disposed opposite to the light incident surface of the light guide plate, In a surface light source device including a mounted light emitting module,
In the middle of the light source position, a notch is provided at the edge of the substrate,
At the light exit surface of the light guide plate or the opposite surface, a reflective tape is attached to the light incident side end of the light guide plate, the reflective tape is projected from the light guide plate toward the light emitting module, and the notch is formed at the edge of the reflective tape. It is characterized in that a protruding piece is provided to be inserted into the hole.

In the surface light source device according to the sixth aspect,
The notch is provided on the substrate on which the light source is provided, and the protruding piece of the reflective tape is inserted into the notch, so that the warp of the reflective tape can be reduced. While holding power can be increased,
By engaging the reflective tape with the substrate, a gap can be prevented from being generated.

[0023]

FIG. 5 is an enlarged partially sectional view showing a surface light source device 21 according to an embodiment of the present invention.
The description of the same components as in the conventional example will be omitted by retaining the same reference numerals.

The light guide plate 2 made of a transparent resin material has an inclined surface 22 at the light incident side end on the surface (lower surface) opposite to the light exit surface 6. The inclined surface 22 is provided over substantially the entire width along the direction of the light incident surface 3. The inclined surface 22 is obliquely downward toward the light incident surface 3. The inclined surface 22 may reach the end on the light incident surface 3 side, or may not reach the end on the light incident surface 3 side.

The reflection tape 14 is a metallic tape having a metallic luster or a resin tape made of a white resin having a high reflectance, and an adhesive or an adhesive is applied to the back surface. As shown in FIG. 5, on the light emitting surface 6 side,
Reflective tape 1 between light emitting surface 6 and upper end surface of wiring board 8
3 is stuck flat. On the lower surface of the light guide plate 2, the reflection tape 14 is adhered to the inclined surface 22 so as to protrude from the light guide plate 2. The end of the reflection tape 14 on the light emitting module 5 side is adhered to the front surface of the wiring board 8. Therefore, the reflection tape 14 is disposed between the light guide plate 2 and the light emitting module 5 with substantially the same inclination as the inclined surface 22 so as not to adhere to the light source 10. The reflective tape 14 may be adhered over substantially the entire width along the direction of the light incident surface 3 of the light guide plate 2 or may be partially adhered only at a position corresponding to the light source 10.

Thus, the light R emitted forward from the light source 10 enters the light guide plate 2 from the concave portion 4 and spreads in the lateral direction by the concave portion 4 when entering the light guide plate 2. on the other hand,
The light R emitted obliquely upward from the light source 10 is reflected by the reflective tape 13 on the upper surface side, and then from the light incident surface 3 to the light guide plate 2.
R incident on the light source and emitted obliquely downward from the light source 10
Also, after being reflected by the reflection tape 14 on the lower surface side, the light enters the light guide plate 2 from the light incident surface 3. As a result, the light coupling efficiency between the light source 10 and the light guide plate 2 is improved, and the luminance of the surface light source device 21 is improved. However, if the inclination of the inclined surface 22 is small, the effect of reducing the warpage of the reflection tape 14 is small, and
If the inclination of 2 is large, the light R reflected by the reflection tape 14 returns to the light source 10 or exits from the light exit surface 6 in the vicinity of the light source 10 (see FIG. 12). There is a need to.

Further, since the reflection tape 14 is substantially flat and is obliquely attached to the light source 10 so as not to adhere to the light source 10, the reflection tape 14 is hardly peeled off from the light guide plate 2 or the wiring board 8 by springback or the like. There is little danger of peeling and falling down.

The boundary region between the flat portion of the lower surface of the light guide plate 2 and the inclined surface 22 may have its inclination gradually changed by a curved surface.

(Second Embodiment) As shown in FIG.
On the lower surface of the light guide plate 2, the slope 22
The reflective tape 14 may be attached to the light emitting module 5, and the edge of the reflective tape 14 may be bent and attached to the front surface of the wiring board 8 on the light emitting module 5 side. However, as shown in the surface light source device 23 of FIG.
If only the edge of the reflective tape 14 (for example, the end of the adhesive on the back surface) is attached to the wiring board 8 on the light emitting module 5 side, the entire reflective tape 14 can be attached straight. Can be.

Therefore, according to the surface light source device 23 of FIG.
As in the embodiment of FIG. 5, the reflective tape 14 floats at the boundary between the flat surface of the lower surface of the light guide plate 2 and the flat surface before the inclined surface 22 and the inclined surface 22, or is bent at the front surface of the wiring board 8. There is no possibility that the reflection tape 14 is peeled off at a portion, the reflection tape 14 can be made harder to peel, and the reliability can be further improved.

(Third Embodiment) FIG. 7 is an enlarged partially sectional view showing a surface light source device 24 according to still another embodiment of the present invention. In this embodiment, one end of the reflective tape 14 is adhered to the lower surface of the light guide plate 2 so that the reflective tape 13 protrudes from the light guide plate 2, and the other end is close to the light emitting module 5. The light-emitting module 5 is suspended in the air without being bonded to the light-emitting module 5.

According to such an embodiment, the reflection tape 14
Although it is slightly warped by its own weight, it is unlikely to be peeled off because it is not forcedly bent by an external force.

(Fourth Embodiment) FIG. 8 is an enlarged partially sectional view showing a surface light source device 25 according to still another embodiment of the present invention. In this embodiment, a protrusion 26 is provided on the front surface of the wiring board 8 of the light emitting module 5 and slightly below the light source 10. To do so, the protrusion 2
6 is preferably provided in a portion intermediate between the light sources 10. One end of the reflection tape 14 is adhered to the lower surface of the light guide plate 2, and the other end of the reflection tape 14 protruding from the light guide plate 2 is adhered to the lower surface of the protrusion 26.

As described above, the protrusion 26 is provided on the front surface of the wiring board 8.
Is provided, the reflection tape 14 can be stopped in a direction perpendicular to the wiring board 8, so that there is a step difference between the end bonded to the light guide plate 2 and the end bonded to the protrusion 26. However, since the reflective tape 14 is applied in a substantially flat state, it is difficult to peel it off.

(Fifth Embodiment) FIG. 9 is a partially broken view showing a surface light source device 27 according to still another embodiment of the present invention, and is a perspective view in a state of being turned upside down. In this embodiment, the inclined surface 22 is formed at the light incident side end on the lower surface of the light guide plate 2, but the inclined surface 22 is not provided at the position of the concave portion 4 and the concave portion 4 The inclined surface 22 is provided only in the middle. The reflection tape 14 is provided on the inclined surface 22 and the light emitting module 5 which are partially provided.
To the wiring board 8. FIG. 10 is a diagram showing a cross section in the middle between the concave portions 4, and FIG. 11 is a diagram showing a cross section in the concave portion 4. The reflecting tape 14 is the light incident surface 3
10, the reflection tape 14 is adhered to the inclined surface 22 as shown in FIG. 10 in the middle of the light source 10, but at a position facing the light source 10. As shown in FIG. 11, there is no inclined surface 22, and the reflection tape 14 is floating in the air.

When an inclined surface 22 having a large inclination angle is provided at a position facing the light source 10, as shown in FIG.
The light R emitted from the light source 10 may be reflected by the lower reflective tape 14 and return to the light source 10, or may be emitted from the light emitting surface 6 near the light source 10 and only locally emit light near the light source 10. is there. Therefore, in this embodiment, the light source 1
The inclined surface 22 is not provided at the position facing 0, and the inclined surface 22 is provided only between the light sources 10 to avoid the inconvenience shown in FIG.

(Sixth Embodiment) In the embodiments described above, the reflection tape 13 is horizontally adhered on the light emitting surface 6 and the reflection tape 14 is obliquely adhered on the lower surface of the light guide plate 2.
This relationship may be reversed. For example, as in a surface light source device 28 shown in FIG. 13, by disposing the light emitting module 5 so as to be deviated toward the upper surface side from the center of the light guide plate 2, the lower end surface of the wiring board 8 has the same height as the lower surface of the light guide plate 2. And a reflective tape 14 on the lower surface side is stuck flat between the lower surface of the light guide plate 2 and the lower end surface of the wiring board 8, and the light exit surface 6 of the light guide plate 2
The reflective tape 13 attached to the inclined surface 22 is projected toward the light emitting module 5.

(Seventh Embodiment) FIG. 14 is a perspective view of a surface light source device 29 according to still another embodiment of the present invention, partially cut away from the lower surface side. In this surface light source device 29, a notch 30 is provided at the lower edge of the wiring board 8 of the light emitting module 5, and a protrusion 31 is formed between the notches 30. The notch 30 is desirably formed between the light source 10 and the light source 10 such that the upper surface (ceiling surface) has the same height as the lower surface of the light guide plate 2. Therefore, the notch 30 extends above the lower end of the light source 10. On the other hand, the reflection tape 14 attached to the lower surface of the light guide plate 2
Has, as shown in FIG. 15, a protruding piece 32 having the same width as the notch 30 of the wiring board 8,
Is formed.

The reflection tape 14 has an end opposite to the projecting piece 32 adhered to the lower surface of the light guide plate 2, projects the projecting piece 32 toward the light emitting module 5, and reflects the projecting part 31 of the wiring board 8. The reflective tape 14 is inserted into the concave portion 33 of the tape 14.
By inserting the protruding piece 32 into the notch 30 of the wiring board 8, the wiring board 8 and the reflection tape 14 are engaged.

With such a shape, the height of the wiring board 8, that is, the place where the light source 10 is provided, is ensured at the place where the height of the wiring board 8 is required.
Can be stuck to the lower surface of the light guide plate 2 with a small warp. Moreover, since the reflection tape 14 can be adhered to the upper surface of the notch 30, the tip of the reflection tape 14 can be held, and a structure in which a gap is hardly generated between the reflection tape 14 and the wiring board 8 can be provided. it can.

(Liquid Crystal Display) FIG. 16 is an exploded perspective view showing a liquid crystal display 81 using the surface light source device 80 according to the present invention. A diffuse reflection sheet 82 is disposed on the front surface of the surface light source device 80, and a liquid crystal display panel 83 is disposed on the front surface. The liquid crystal display panel 83 includes a transparent electrode and a TF.
Two liquid crystal substrates (glass substrate, film substrate) 84 on which T, color filters, black matrix, etc. are formed,
A liquid crystal material is sealed between the liquid crystal substrates 85, and polarizing plates 86 are provided on both outer surfaces of the liquid crystal substrates 84 and 85.

According to such a liquid crystal display device 81, the surface light source device 80 having a high light coupling efficiency between the light source 32 and the light guide plate 22 and a high luminance can be used. Can be enhanced.

(Electronic Device Equipped with Liquid Crystal Display Device) The liquid crystal display device according to the present invention is a wireless information transmission device such as a mobile phone or a low power radio device, a portable personal computer, an information processing device such as an electronic organizer or a calculator. It is preferable to use it for devices and the like. FIG. 17 is a perspective view showing a mobile phone 89 provided with a liquid crystal display device 81 as shown in FIG. 16 for display according to the present invention, and FIG. 18 is a functional block diagram thereof. A button switch 90 such as a numeric keypad for dial input is provided on the front of the mobile phone 89, a liquid crystal display device 81 is provided above the switch 90, and an antenna 91 is provided on the upper surface. When a dial or the like is input from the button switch 90, the input dial information or the like is transmitted from the antenna 91 to the base station of the telephone company through the transmission circuit 92. On the other hand, the input dial information and the like are sent to the liquid crystal drive circuit 93, and the liquid crystal display device 81 is driven by the liquid crystal drive circuit 93, and the dial information and the like are displayed on the liquid crystal display device 81.

FIG. 19 is a diagram showing an example of FIG.
6. A portable information terminal 9 such as an electronic organizer or a portable personal computer having a liquid crystal display device 81 as shown in FIG.
4 is a perspective view, and FIG. 20 is a functional block diagram thereof.
When the cover 95 is opened, the portable information terminal 94 includes a key input section 96 and a liquid crystal display device 81. Inside the portable information terminal 94, a liquid crystal driving circuit 93, an arithmetic processing circuit 97, and the like are provided.
Thus, for example, when a ten key, a kana key, or the like is input from the key input unit 96, the input information is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81. Next, when a control key such as a calculation key is pressed, predetermined processing and calculation are executed in the calculation processing circuit 97, and the result is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a conventional surface light source device.

FIG. 2 is a plan view of the surface light source device.

FIG. 3 is a cross-sectional view showing a surface light source device in which a reflective tape is attached between an upper surface of a light emitting module and a light guide plate.

FIG. 4 is a partially broken cross-sectional view showing a conventional surface light source device in which a reflection tape is also applied between a lower surface of a light emitting module and a light guide plate.

FIG. 5 is an enlarged partially sectional view showing the surface light source device according to the embodiment of the present invention.

FIG. 6 is an enlarged sectional view showing a surface light source device according to another embodiment of the present invention, with a part cut away.

FIG. 7 is an enlarged cross-sectional view showing a surface light source device according to still another embodiment of the present invention, with a part cut away.

FIG. 8 is an enlarged partially sectional view showing a surface light source device according to still another embodiment of the present invention.

FIG. 9 is a partially cutaway perspective view showing a surface light source device according to still another embodiment of the present invention from the back side.

FIG. 10 is a partially broken sectional view of the surface light source device of the above.

FIG. 11 is a partially broken sectional view of the surface light source device of the above.

FIG. 12 is a diagram for explaining the operation of the embodiment.

FIG. 13 is an enlarged partially sectional view showing a surface light source device according to still another embodiment of the present invention.

FIG. 14 is a partially cut away perspective view showing a surface light source device according to still another embodiment of the present invention.

FIG. 15 is a partially broken plan view showing the reflective tape of the above.

FIG. 16 is an exploded perspective view of a liquid crystal display device using the surface light source device of the present invention.

FIG. 17 is a perspective view showing a mobile phone provided with a liquid crystal display device according to the present invention for a display.

FIG. 18 is a block diagram showing a configuration for driving a liquid crystal display device in the above mobile phone.

FIG. 19 is a perspective view showing a portable information terminal such as an electronic organizer provided with a liquid crystal display device according to the present invention for a display.

FIG. 20 is a block diagram showing a configuration for driving a liquid crystal display device in the portable information terminal of the above.

[Explanation of symbols]

 Reference Signs List 2 light guide plate 4 concave portion 5 light emitting module 8 wiring board 10 light source 13, 14 reflective tape 22 inclined surface 26 protrusion 30 cutout 32 protrusion

Claims (6)

[Claims] 1. A surface having a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light emitting module having a light source mounted on a substrate, which is disposed to face the light incident surface of the light guide plate. In the light source device, an inclined surface is provided at a light incident side end of the light guide plate on the light emitting surface or the opposite surface of the light guide plate, and the reflection tape attached to the inclined surface is projected from the light guide plate toward the light emitting module. A surface light source device. 2. The surface light source device according to claim 1, wherein a reflection tape is attached to the light guide plate only on the inclined surface. 3. The surface light source device according to claim 1, wherein the inclined surface is partially provided along a light incident side end of the light guide plate. 4. A surface having a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light emitting module having a light source mounted on a substrate, which is disposed to face the light incident surface of the light guide plate. In the light source device, a reflection tape is attached to a light incident side end of the light guide plate on the light emission surface or the opposite surface of the light guide plate, and the reflection tape is projected from the light guide plate toward the light emitting module, and the light emission of the reflection tape is performed. A surface light source device wherein an end on the module side is separated from the light emitting module. 5. A surface having a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light emitting module having a light source mounted on a substrate, which is disposed to face the light incident surface of the light guide plate. In the light source device, a reflective tape is attached to a light incident side end of the light guide plate on the light emitting surface or the opposite surface of the light guide plate, and the reflective tape is protruded from the light guide plate toward the light emitting module. A surface light source device, wherein an end of a reflection tape on a light emitting module side is attached to a protrusion provided on a surface on a mounting side. 6. A surface provided with a light guide plate for introducing light from a light incident surface and extracting light from a light exit surface, and a light emitting module having a light source mounted on a substrate and disposed opposite to the light incident surface of the light guide plate. In the light source device, a notch is provided at an edge of the substrate in the middle of the light source position,
At the light exit surface of the light guide plate or the opposite surface, a reflective tape is attached to the light incident side end of the light guide plate, the reflective tape is projected from the light guide plate toward the light emitting module, and the notch is formed at the edge of the reflective tape. A surface light source device characterized by comprising a projection inserted into the surface light source.