JP7047799B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting device.

As a conventional technique, a light emitting device including a light source and a light guide plate that guides light incident from the light source, deflects the guided light through an optical path, and emits an image from an exit surface to form an image in space. Are known.

Japanese Unexamined Patent Publication No. 2016-114929 (published on June 23, 2016)

In the conventional light emitting device, in a normal usage environment, as shown in FIGS. 5 and 7A, the amount of light emitted from the light guide plate gradually increases from the vicinity of the observation angle of 0 degrees, and the observation angle is particularly high. At around 30 to 60 degrees, the amount of emitted light becomes maximum. Here, the observation angle is an angle formed by the normal of the exit surface of the light guide plate and the path of the light emitted from the light guide plate and visually recognized by the observer (in FIG. 7A, the right side (the side far from the light source) is +, The left side (the side closer to the light source) indicates-). In reality, the light guide plate is arranged so that the normal direction of the surface is the horizontal direction. That is, in FIG. 7A, the left side is the downward direction and the right side is the upward direction.

However, as shown in FIGS. 6 and 7A, when the light emitting device is exposed to an unexpectedly high temperature (140 degrees) environment, the shape of the light guide plate formed of the resin material may be deformed. In FIG. 6, in the shape of the cross section of the light guide plate, the deepest portion of the groove constituting the optical path deflection portion becomes shallow, and the inclined portion of the groove becomes small. Therefore, as shown in FIG. 7B, in an environment of 140 degrees, almost no light emitted from the light guide plate is present near an observation angle of -20 to 30 degrees, and the peak of the amount of emitted light is an observation angle of 70 degrees. It shifts to about. As a result, there is a problem that the light cannot be visually recognized from the assumed position of the observer. For example, when this light emitting device is used for a tail lamp of a vehicle or the like, if the light becomes invisible, a safety problem arises.

In view of the above problems, one aspect of the present invention is to realize a light emitting device in which the light emitted from the light guide plate can be visually recognized by an observer even if the surrounding environment becomes an unexpectedly high temperature. do.

In order to solve the above problems, the light emitting device according to one aspect of the present invention guides the light source and the light incident from the light source, and deflects the guided light to emit light from the emission surface. A light emitting device including a light guide plate for forming an image on space, wherein the light guide plate includes a light path deflection unit group having a reflection surface for light path deflecting the light, and the optical path deflection unit group includes a light path deflection unit group. Includes a first optical path deflection unit group in which the angle of the reflection surface with respect to the emission surface is 30 to 55 degrees, and a second optical path deflection unit group in which the angle of the reflection surface with respect to the emission surface is 65 degrees or more. ..
According to the above configuration, the inclination angle of the first optical path deflection unit group becomes small due to the high temperature of the surrounding environment of the light emitting device, and even if it becomes invisible to the observer, it is deflected by the second optical path deflection unit group. The emitted light becomes visible. Therefore, it can be applied even when it is used in an application where the visual recognition of light emission is surely required.

In order to solve the above problems, in the light emitting device according to one aspect of the present invention, the number of optical path deflection units constituting the first optical path deflection unit group is the number of optical path deflection units constituting the second optical path deflection unit group. It may be 4 times or more of the number of.
According to the above configuration, in a normal environment, the amount of emitted light deflected by the first optical path deflecting group can be sufficiently secured, and the emitted light deflected by the first optical path deflecting group can be sufficiently secured. Even when it becomes invisible, the emitted light deflected by the second optical path deflection unit group is at least visible, so that safety can be ensured.

In order to solve the above problems, in the light emitting device according to one aspect of the present invention, the image formed by the second optical path deflection unit group is an image showing that an abnormality has occurred in the light guide plate. There may be.
According to the above configuration, by showing the observer that the emitted light deflected by the first optical path deflection group is invisible due to the image formed by the second optical path deflection group. , Repair and replacement of the light guide plate can be promoted, and safety can be ensured.

In order to solve the above problems, in the light emitting device according to one aspect of the present invention, the image by the first optical path deflection unit group is imaged in a space different from the arrangement position of the light guide plate, while the above. The image produced by the second optical path deflection unit group may be imaged on the surface of the light guide plate.
According to the above configuration, since the image formed at the time of abnormality is different from the image formed at the time of normal, the observer can recognize that the light emitting device has an abnormality, and the safety can be improved. Can be secured.

In order to solve the above problems, the light emitting device according to one aspect of the present invention has an area of a region where the first optical path deflection unit group is formed and a region where the second optical path deflection unit group is formed. The sum with the area may be 30% or less of the total area of the exit surface of the light guide plate.
According to the above configuration, since the pattern is not visually recognized and the light guide plate feels transparent, it is possible to provide a light emitting device having excellent design.
In order to solve the above-mentioned problems, the light emitting device according to one aspect of the present invention has the optical path deflection unit group.
A third optical path deflection unit group in which the angle of the reflecting surface with respect to the emitting surface is 55 to 65 degrees may be further included.
According to the above configuration, it is observed that a problem occurs in the light emitting device by the image by the third optical path deflection group before the emitted light deflected by the first optical path deflection group becomes completely invisible. Since it is recognized by the person, the user can take measures such as replacement of the light emitting device more quickly.

According to one aspect of the present invention, even if the surrounding environment becomes an unexpectedly high temperature, it is possible to realize a light emitting device in which the light emitted from the light guide plate is visible to the observer.

It is a side view of the light emitting device 4 which concerns on Embodiment 1 of this invention. It is a top view which shows the structural example of the light guide plate provided in the light emitting device of this invention. It is a perspective view which shows the image formation method of the stereoscopic image by the light emitting device of FIG. It is a perspective view which shows the image formation method of the stereoscopic image by the light emitting device different from the light emitting device of FIG. 2 of this invention. It is a graph which shows the measurement result of the directivity of the emitted light by the light guide plate of the conventional light emitting device. It is a figure which shows the cross-sectional shape change with temperature in the light guide plate of the conventional light emitting device. It is a figure which shows the distribution of the observation angle at a normal temperature of a light guide plate in a conventional light emitting device. It is a figure which shows the distribution of the observation angle in the high temperature environment of the light guide plate in the conventional light emitting device.

Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as “the present embodiment”) will be described with reference to the drawings.

First, a method of forming a stereoscopic image in a light emitting device according to an embodiment of the present invention will be described.

[Image forming method 1 of stereoscopic image]
FIG. 2A is a cross-sectional view showing the configuration of the light emitting device 4 according to the present embodiment. As shown in FIG. 2A, the light emitting device 4 includes a light source 12 and a light guide plate 11 (first light guide plate). FIG. 2B is a plan view showing the configuration of the light guide plate 11 included in the light emitting device 4.

In FIGS. 2 to 4, the direction in which the light incident on the light guide plate 11 from the light source 12 is guided through the light guide plate 11 is the Y-axis direction, and the direction in which the light is emitted from the light guide plate 11 is the Z-axis direction. The direction perpendicular to both the Y-axis direction and the Z-axis direction is defined as the X-axis direction.

The light guide plate 11 is a member that guides the light (incident light) incident from the light source 12. The light guide plate 11 is made of a transparent resin material having a relatively high refractive index. As the material for forming the light guide plate 11, for example, a polycarbonate resin, a polymethylmethacrylate resin, or the like can be used. In this embodiment, the light guide plate 11 is made of a polymethylmethacrylate resin. As shown in FIG. 2A, the light guide plate 11 includes an emission surface 11a (light emission surface), a back surface 11b, and an entrance surface 11c.

The emission surface 11a is a surface that guides the inside of the light guide plate 11 and emits light whose optical path is changed by the optical path deflection unit 16 similar to the optical path deflection unit 13. The emission surface 11a constitutes the front surface of the light guide plate 11. The back surface 11b is a surface parallel to the exit surface 11a, and is a surface on which the optical path deflection portion 16 described later is arranged. The incident surface 11c is a surface on which the light emitted from the light source 12 is incident on the inside of the light guide plate 11.

The light emitted from the light source 12 and incident on the light guide plate 11 from the incident surface 11c is totally reflected by the emission surface 11a or the back surface 11b and guided through the light guide plate 11.

As shown in FIG. 2A, the optical path deflection portion 16 is formed on the back surface 11b inside the light guide plate 11, and changes the optical path of the light guided in the light guide plate 11 from the emission surface 11a. It is a member for emitting light. A plurality of optical path deflection portions 16 are provided on the back surface 11b of the light guide plate 11.

The optical path deflection portion 16 is provided along a direction (X-axis) parallel to the incident surface 11c. The optical path deflecting portion 16 has a triangular pyramid shape and includes a reflecting surface Ra that reflects (totally reflected) the incident light. The optical path deflection portion 16 may be, for example, a recess formed in the back surface 11b of the light guide plate 11. The optical path deflection portion 16 is not limited to the triangular pyramid shape. As shown in FIG. 2B, a plurality of optical path deflection section rows 17a, 17b, 17c ... Consisting of a plurality of optical path deflection sections 16 are formed on the back surface 11b of the light guide plate 11.

In each of the optical path deflection unit rows 17a, 17b, 17c ..., The plurality of optical path deflection units 16 are arranged on the back surface 11b of the light guide plate 11 so that the reflecting surfaces Ra have different angles with respect to the incident direction of the light. As a result, each of the optical path deflection unit rows 17a, 17b, 17c ... changes the optical path of the incident light and emits the incident light from the emission surface 11a in various directions.

Next, a method of forming a stereoscopic image I by the light emitting device 4 will be described with reference to FIG. Here, a case will be described in which a stereoscopic image I as a surface image is formed on the stereoscopic image forming surface P which is a plane perpendicular to the emission surface 11a of the light guide plate 11 by the light whose optical path is changed by the optical path deflection unit 16. ..

FIG. 14 is a perspective view showing a method of forming a stereoscopic image I by the light emitting device 4. Here, it will be described that an image having a diagonal line in a circle is formed as a stereoscopic image I on the stereoscopic image forming surface P.

In the light emitting device 4, as shown in FIG. 14, for example, the light whose optical path is changed by each optical path deflection unit 16 of the optical path deflection unit row 17a intersects the stereoscopic image forming surface P with the line La1 and the line La2. As a result, the line image LI, which is a part of the stereoscopic image I, is formed on the stereoscopic image forming surface P. The line image LI is a line image parallel to the YZ plane. In this way, the line image LI of the line La1 and the line La2 is formed by the light from a large number of optical path deflection units 16 belonging to the optical path deflection unit row 17a. The light that forms an image of the line La1 and the line La2 may be provided by at least two optical path deflection portions 16 in the optical path deflection unit row 17a.

Similarly, the light whose optical path is changed by each optical path deflection unit 16 of the optical path deflection unit row 17b intersects the stereoscopic image forming surface P at the line Lb1, the line Lb2, and the line Lb3. As a result, the line image LI, which is a part of the stereoscopic image I, is formed on the stereoscopic image forming surface P.

Further, the light whose optical path is changed by each optical path deflection unit 16 of the optical path deflection unit row 17c intersects the stereoscopic image forming surface P at the line Lc1 and the line Lc2. As a result, the line image LI, which is a part of the stereoscopic image I, is formed on the stereoscopic image forming surface P.

The positions of the line images LI imaged by the optical path deflection portions 17a, 17b, 17c ... In the Z-axis direction are different from each other. In the light emitting device 4, by reducing the distance between the optical path deflection unit rows 17a, 17b, 17c ..., the distance in the Z-axis direction of the line image LI imaged by each optical path deflection unit row 17a, 17b, 17c ... It can be made smaller. As a result, in the light emitting device 4, by accumulating a plurality of line image LIs imaged by the light whose optical path is changed by each of the optical path deflection portions 16 of the optical path deflection unit rows 17a, 17b, 17c ... The stereoscopic image I, which is an image, is formed on the stereoscopic image forming surface P.

The stereoscopic image forming surface P may be a plane perpendicular to the Z axis, a plane perpendicular to the Y axis, or a plane perpendicular to the X axis. Further, the stereoscopic image forming surface P may be a plane that is not perpendicular to the Z-axis, the Y-axis, or the X-axis. Further, the stereoscopic image forming surface P may be a curved surface instead of a plane. That is, the light emitting device 4 can form a stereoscopic image I on an arbitrary surface (plane and curved surface) in space by the optical path deflection unit 16. Further, by combining a plurality of surface images, a three-dimensional image can be formed.

[Image forming method 2 of stereoscopic image]
Next, with reference to FIG. 4, a method of forming a stereoscopic image in a light emitting device according to another embodiment of the present invention will be described.

FIG. 4 is a diagram showing a configuration example of the light emitting device 1. FIG. 4 shows a state in which the light emitting device 1 displays a stereoscopic image P, more specifically, a button-shaped stereoscopic image P in which the character “ON” is displayed.

The light guide plate 11 has a rectangular parallelepiped shape and is made of a resin material having transparency and a relatively high refractive index. The material forming the light guide plate 11 may be, for example, a polycarbonate resin, a polymethylmethacrylate resin, glass, or the like. The light guide plate 11 has an emission surface 11a (light emission surface) that emits light, a back surface 11b on the opposite side of the emission surface 11a, and end faces 11c, end faces 11d, end faces 11e, and end faces 11f that are four end faces. I have. The end face 11c is an incident surface on which the light projected from the light source 12 is incident on the light guide plate 11. The end surface 11d is a surface opposite to the end surface 11c. The end surface 11e is a surface opposite to the end surface 11f. The light guide plate 11 guides the light incident from the light source 12 and emits it from the emission surface 11a to form an image in space. The light source 12 is, for example, an LED (Light Emitting diode) light source.

A plurality of optical path deflection portions 13 including an optical path deflection portion 13a, an optical path deflection portion 13b, and an optical path deflection portion 13c are formed on the back surface 11b of the light guide plate 11. The optical path deflection portion 13a, the optical path deflection portion 13b, and the optical path deflection portion 13c are formed along the line La, the line Lb, and the line Lc, respectively. Here, the line La, the line Lb, and the line Lc are straight lines substantially parallel to the X-axis direction. The arbitrary optical path deflection portion 13 is formed substantially continuously in the X-axis direction. In other words, the plurality of optical path deflection portions 13 are formed along predetermined lines in a plane parallel to the exit surface 11a.

Light projected from the light source 12 and guided by the light guide plate 11 is incident on each position of the optical path deflection portion 13 in the X-axis direction. The optical path deflection unit 13 substantially converges the light incident on each position of the optical path deflection unit 13 to a fixed point corresponding to each optical path deflection unit 13. In FIG. 3, the optical path deflection unit 13a, the optical path deflection unit 13b, and the optical path deflection unit 13c are particularly shown as a part of the optical path deflection unit 13. Further, in FIG. 3, in each of the optical path deflection unit 13a, the optical path deflection unit 13b, and the optical path deflection unit 13c, a plurality of lights emitted from each of the optical path deflection unit 13a, the optical path deflection unit 13b, and the optical path deflection unit 13c are emitted. The state of convergence is shown.

Specifically, the optical path deflection unit 13a corresponds to the fixed point PA of the stereoscopic image P. The light from each position of the optical path deflection portion 13a converges on the fixed point PA. Therefore, the wavefront of the light from the optical path deflection portion 13a becomes the wavefront of the light emitted from the fixed point PA. The optical path deflection unit 13b corresponds to the fixed point PB on the stereoscopic image P. The light from each position of the optical path deflection portion 13b converges on the fixed point PB. In this way, the light from each position of the arbitrary optical path deflection unit 13 substantially converges to the fixed point corresponding to each optical path deflection unit 13. Thereby, it is possible to provide a wavefront of light such that light is emitted from a corresponding fixed point by an arbitrary optical path deflection unit 13. The fixed points corresponding to each optical path deflection unit 13 are different from each other, and the user is placed on the space (more specifically, on the space on the exit surface 11a side from the light guide plate 11) by a collection of a plurality of fixed points corresponding to the optical path deflection units 13. The stereoscopic image P recognized by is imaged.

However, the above describes the method for realizing the three-dimensional display, and the actual design and the like are changed as appropriate depending on the applicable product such as a vehicle lamp, a vehicle display device, and the like.

[Embodiment 1]
§1 Configuration example An example of a situation to which this embodiment is applied will be described below with reference to FIG. Products to which this embodiment is applied are, for example, vehicle lamps, vehicle display devices, and the like, but are not particularly limited. Further, in FIG. 1, the direction in which the light incident on the light guide plate 11 from the light source 12 is guided through the light guide plate 11 is the Y-axis direction, and the normal direction of the light guide plate 11 is the Z-axis direction, and the Y-axis direction and The direction perpendicular to both the Z-axis directions is defined as the X-axis direction.

FIG. 1 is a cross-sectional view showing the configuration of the light emitting device 1 according to the present embodiment and the configuration of the light emitting device 4. As shown in FIG. 1, the light emitting device 4 includes a light source 12 and a light guide plate 11.
The light source 12 causes light to enter the light guide plate 11. In the example shown in FIG. 1, there is only one light source 12.

The light guide plate 11 guides the light incident from the light source 12, and deflects the guided light in an optical path to emit the light from the emission surface 11a, thereby forming an image in space. The light guide plate 11 is formed into a rectangular parallelepiped shape having a thin thickness in the Z-axis direction, and includes an upper surface 11a (emission surface) and a back surface 11b parallel to each other, and an incident surface 11c. Examples of the constituent material of the light guide plate 11 include a transparent resin material having a relatively high refractive index. As the material for forming the light guide plate 11, for example, polycarbonate resin (PC), polymethylmethacrylate resin (PMMA), glass, or the like can be used.
The emission surface 11a is a surface that guides the inside of the light guide plate 11 and emits light whose optical path is changed by the optical path deflection unit 16 similar to the optical path deflection unit 13. The emission surface 11a constitutes the front surface of the light guide plate 11. The back surface 11b is a surface parallel to the exit surface 11a, and is a surface on which the optical path deflection portion 16 described later is arranged. The incident surface 11c is a surface on which the light emitted from the light source 12 is incident on the inside of the light guide plate 11.

The light emitted from the light source 12 and incident on the light guide plate 11 from the incident surface 11c is totally reflected by the emission surface 11a or the back surface 11b and guided through the light guide plate 11.

As shown in FIG. 1, the optical path deflection portion 16 is formed on the back surface 11b inside the light guide plate 11 to change the optical path of the light guided in the light guide plate 11 and emit it from the emission surface 11a. It is a member. A plurality of optical path deflection portions 16 are provided on the back surface 11b of the light guide plate 11.

The optical path deflection portion 16 is provided along a direction (X-axis) parallel to the incident surface 11c. The optical path deflecting portion 16 has a triangular pyramid shape and includes a reflecting surface Ra that reflects (totally reflected) the incident light. The optical path deflection portion 16 may be, for example, a recess formed in the back surface 11b of the light guide plate 11. The optical path deflection portion 16 is not limited to the triangular pyramid shape. As shown in FIG. 1, the back surface 11b of the light guide plate 11 is formed with a plurality of optical path deflection portions 16a and 16b including a plurality of optical path deflection portions 16.

In each of the optical path deflection portions 16a and 16b, the plurality of optical path deflection portions 16 are arranged on the back surface 11b of the light guide plate 11 so that the inclination angles α1 and α2 of the reflection surfaces Ra and Rb are different from each other. The inclination angle indicates the angle of the reflecting surfaces Ra and Rb with respect to the emitting surface 11a. As a result, each of the optical path deflection unit groups 16a and 16b changes the optical path of the incident light and emits the incident light from the emission surface 11a in different directions.

Further, in the present embodiment, the sum of the area of the region where the first optical path deflection portion group 16a is formed and the area of the region where the second optical path deflection portion group 16b is formed is the sum of the area of the light guide plate. It is 30% or less of the total area of the exit surface 11a. As described above, since the area where the optical path deflection portions 16a and 16b are formed is small with respect to the total area of the exit surface 11a, the image pattern is difficult to see and the light guide plate feels transparent, which improves the design. An excellent light emitting device 4 can be provided.
As described above, the light guide plate 11 includes optical path deflection unit groups 16a and 16b having reflecting surfaces Ra and Rb that deflect the light in the optical path, respectively. Further, the optical path deflection unit group includes a first optical path deflection unit group 16a and a second optical path deflection unit group 16b.
In the present embodiment, the number of optical path deflection portions constituting the first optical path deflection unit group 16a is four times the number of optical path deflection portions constituting the second optical path deflection unit group 16b.
The optical path deflection portions constituting the first optical path deflection portion group 16a are all made of the same material. The optical path deflection portion constituting the first optical path deflection portion group 16a has an inclination angle α1 of 30 to 55 degrees.
On the other hand, the optical path deflection portion constituting the second optical path deflection portion group 16b has an inclination angle α2 of 65 degrees or more.
Therefore, the image formed by the emitted light reflected by the reflecting surfaces Ra and Rb has different image forming directions.

As shown in FIG. 1, the light deflected by the optical path deflection unit constituting the first optical path deflection unit group 16a forms an image within a range Aa having an observation angle of about −20 to 30 degrees. Therefore, in a normal usage environment, that is, in the issuing device 4 used only in the usable temperature range, the imaged image can be sufficiently visually recognized from the position of a normal observer.
On the other hand, as shown in FIG. 1, the light deflected by the optical path deflection unit constituting the second optical path deflection unit group 16b forms an image within a range Ab having an observation angle of about -40 degrees or less. Therefore, in the issuing device 4 used only in a normal usage environment, the imaged image cannot be visually recognized from the position of a normal observer.

On the other hand, in the issuing device 4 which has experienced being placed in an unexpectedly high temperature environment, for example, an environment having a temperature of 140 degrees or higher, the shape of the pattern on the light guide plate changes as described above. As a result, the position of the image formed by the light deflected by the optical path deflection unit group is displaced to the side where the observation angle is high, that is, to the right side in FIG.

That is, the light deflected by the optical path deflection unit constituting the first optical path deflection unit group 16a is formed into an image within the range Ba shown in FIG. 1. As a result, the imaged image is tilted to the right side of the range that the observer can see, so that the image cannot be seen by the observer.

On the other hand, the image formed by the light deflected by the optical path deflection unit constituting the second optical path deflection unit group 16b also has a large observation angle in the issuing device 4 which has experienced being placed in a high temperature environment. Move to the side, that is, to the range Bb on the right side in FIG. As a result, the image formed by the light deflected by the optical path deflection unit constituting the second optical path deflection unit group 16b, which could not be visually recognized under a normal environment, can be visually recognized by the observer. ..

As described above, according to the first embodiment, the emitted light deflected by the optical path deflection unit of the first optical path deflection unit group 16a, which can be visually recognized in a normal state, can be visually recognized by being placed in an unexpected high temperature environment. Even if it disappears, the emitted light deflected by the optical path deflection portion of the second optical path deflection portion group 16b can be visually recognized. Therefore, for example, when the lamp is used for a vehicle lamp or the like, the light emission can be visually recognized by the observer even after experiencing a high temperature environment, and safety can be ensured.

Further, according to the first embodiment, the first optical path deflection unit group 16a includes four times as many optical path deflection units as the second optical path deflection unit group 16b, so that the observer can use the normal environment. , The image can be visually recognized with a sufficient amount of light.

[Embodiment 2]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will not be repeated.

In the first embodiment, the image formed by the light deflected by the optical path deflection unit constituting the second optical path deflection unit group 16b is also the light deflected by the optical path deflection unit constituting the first optical path deflection unit group 16a. Both of the images formed by the image were stereoscopic images.

However, in the light emitting device of the present invention, the image by the first optical path deflection unit group is imaged in a space different from the arrangement position of the light guide plate, while the image by the second optical path deflection unit group is the above. An image may be formed on the surface of the light guide plate. That is, the image produced by the second optical path deflection unit group may be a planar image formed on the surface of the light guide plate.

According to the above configuration, since the image is formed on the plane of the light guide plate, the observer can recognize that the light emitting device has an abnormality. Therefore, safety can be ensured by encouraging repair and replacement of the light guide plate.
[Embodiment 3]
In the first embodiment, the optical path deflection unit group consists of two types, an optical path deflection unit constituting the first optical path deflection unit group 16a and an optical path deflection unit constituting the second optical path deflection unit group 16b, which have different inclination angles from each other. An example having an optical path deflection group is described.

However, the optical path deflection unit group may further include a third optical path deflection unit group in which the angle of the reflection surface with respect to the emission surface is 55 to 65 degrees. According to the third optical path deflection unit group, the optical path constituting the first optical path deflection unit group 16a is before the image due to the light deflected by the optical path deflection unit constituting the first optical path deflection unit group 16a becomes completely invisible. The image due to the light deflected by the deflection unit can be visually recognized. Therefore, before the image due to the light deflected by the optical path deflection unit constituting the first optical path deflection unit group 16a becomes invisible, the observer causes an abnormality in the light emitting device by the optical path deflection unit of the third optical path deflection unit group. It can be recognized, and the user can take measures such as replacement of the light emitting device more quickly.
[Embodiment 4]
The image formed by the second optical path deflection unit group 16b may be an image showing that an abnormality has occurred in the light guide plate. For example, characters or symbols notifying the observer that an abnormality has occurred in the light emitting device may be displayed together with the image to be imaged.
In the above description, an example in which the optical path deflection unit constituting the first optical path deflection unit group 16a and the optical path deflection unit constituting the second optical path deflection unit group 16b are arranged in a row has been described. However, in the first embodiment, the relative positions of the optical path deflection unit constituting the first optical path deflection unit group 16a and the optical path deflection unit constituting the second optical path deflection unit group 16b are determined by the respective optical path deflection unit groups. It may be arbitrary depending on the position of the image to be imaged.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1, 4 Light emitting device 11 Light guide plate 11a Emission surface 11b Back surface 11c Incident surface 12 Light source 13, 13a, 13b, 13c, 16 Optical path deflection part 16a First optical path deflection part group 16b Second optical path deflection part group 17a, 17b, 17c Optical path Deflection section Ra, Rb Reflective surface a, a1, a2, b, b1, b2, b3, c, c1, c2 Line L
Aa, Ab Range Ba, Bb Range α1, α2 Tilt angle

Claims (6)

Light source and
A light emitting device including a light guide plate that guides light incident from the light source, deflects the guided light through an optical path, and emits the guided light from an emission surface to form an image in space.
The light guide plate includes an optical path deflection unit group having each reflecting surface for optical path deflection of the light.
The optical path deflection unit group is
The first optical path deflection unit group in which the angle of the reflecting surface with respect to the emitting surface is 30 to 55 degrees,
A light emitting device including a second optical path deflection unit group in which the angle of the reflecting surface with respect to the emitting surface is 65 degrees or more. The light emitting device according to claim 1, wherein the number of optical path deflection units constituting the first optical path deflection unit group is four times or more the number of optical path deflection units constituting the second optical path deflection unit group. The light emitting device according to claim 1 or 2, wherein the image formed by the second optical path deflection unit group is an image showing that an abnormality has occurred in the light guide plate. While the image produced by the first optical path deflection unit group is formed in a space different from the arrangement position of the light guide plate, the image is formed.
The light emitting device according to any one of claims 1 to 3, wherein the image produced by the second optical path deflection unit group is imaged on the surface of the light guide plate. The sum of the area of the region where the first optical path deflection portion group is formed and the area of the region where the second optical path deflection portion group is formed is 30% of the total area of the emission surface of the light guide plate. The light emitting device according to any one of claims 1 to 4 below. The optical path deflection unit group is
The light emitting device according to any one of claims 1 to 5 , further comprising a third optical path deflection unit group in which the angle of the reflecting surface with respect to the emitting surface is 55 to 65 degrees.

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