JP2002175031A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems in a display device, having an LED as inner illumination when the optical axis of the LED is made perpendicular to the display screen. SOLUTION: Light emission in a conical state from an LED 69 is partially reflected by a flat face 75 (L1) or scattered and reflected (L2, L3) on an inclined face 71 to propagate to a display plate 56. The light includes light L4, directly propagating to the display plate 56 or includes such light once reflected by a substrate 67, an inner wall 65 or the like to propagate to the display plate 56. Because most of the light, emitting from the LED 69, propagates toward the display plate 56, characters in the center of the display plate 56, namely, characters of 'STOP' can be displayed very clearly with a small number of LEDs 69. The direction of the light propagating to the display plate 56 is random, and since the light, emitting from many LEDs 69, is mixed so that the display plate 56 will not be affected by the color irregularities or luminance irregularities of each LED 69.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a display device in which a light emitting diode is internally illuminated.

[0002]

2. Description of the Related Art A display device in which a box-shaped body is formed by a frame member and front and back members, and a light source is disposed inside, and for example, characters and figures on a display surface are raised or conspicuous by light directed from the light source to the outside. (For example, signboards). In addition, in many cases, one of the front and back members also serves as the display surface.

[0003]

When a light bulb or a fluorescent lamp is used as the internal light source, there is no particular problem because the direction of the light emitted from these bulbs is small,
When a light emitting diode (hereinafter, also referred to as an “LED”) is used, there is a problem that the light emission direction is limited to the vicinity of the optical axis.

Specifically, conventionally, the optical axis of the LED is set to be perpendicular to the display surface, so that the area where one LED illuminates the display surface is narrow (spots), and in order to illuminate a wide area, Many LEDs had to be arranged, for example, in a matrix. In addition, when the number of LEDs is reduced, there is a problem that the display surface has a difference in brightness and is hard to see.

[0005]

According to a first aspect of the present invention, there is provided a display device, comprising: a frame member, a front member for closing one opening of the frame member, and a face to face with the front member. A box-shaped body composed of a back member arranged as
In a display device including a light-emitting diode disposed inside the box-shaped body and a display surface for displaying information by transmitting light derived from the light-emitting diode, the light-emitting diode has an optical axis equal to the display surface. It is characterized by being arranged in a parallel direction.

[0006] Since the light emitted from the LED spreads conically around its optical axis, the light in the spread portion transmits through the display surface to display information. Also, there is light that is reflected inside the box-shaped body and passes through the display surface. In short, since the direction in which the light originating from the LED passes through the display surface becomes random, the display surface can be made to have substantially uniform brightness.
Moreover, the number of LEDs is extremely small as compared with a case where the LEDs are arranged in a matrix with the optical axis perpendicular to the display surface.

The frame member and the front member or the back member may be integrally formed, for example, so that the manufacturing process can be simplified and the manufacturing cost can be reduced. According to a second aspect of the present invention, in the display device of the first aspect, since the display surface is provided on the front member or the back member, a member for forming the display surface (a plate material, a sheet, a film, or the like). ) Is not required. That is, the structure is simplified.
The display surface may be provided on both the front member and the back member.

According to a third aspect of the present invention, in the display device according to the first or second aspect, a scattering plate for scattering transmitted light is disposed between the light emitting diode and the display surface. The direction of the light to be emitted can be made more random,
The display surface can be made more evenly bright.

The scattering plate is formed, for example, by printing a white pigment or the like on the surface of a transparent resin plate, dispersing the white pigment inside the transparent resin plate by so-called kneading, or roughening one or both surfaces of the transparent plate. This can be realized by using a surface (scattering surface). According to a fourth aspect of the present invention, in the display device according to the first or second aspect, the display surface is provided only on the front member, and the back surface is provided along a direction parallel to an optical axis of the light emitting diode. And a scattering reflection surface disposed farther from the light emitting diode than the flat surface.

[0010] Since a flat surface arranged along a direction parallel to the optical axis of the light emitting diode and a scattering reflection surface arranged farther from the light emitting diode than the flat surface are provided on the back member side, the LED is provided. A portion of the light (the portion that goes to the flat surface side from the optical axis) emitted from the light beam in a conical shape is reflected by the flat surface, and its direction is changed to the optical axis side. Light from the flat surface goes to the display surface (front member) arranged at a position facing the flat surface (back plate member). Although the light from the LED is emitted in a conical shape, the apex angle of the cone is not large (for example, 20 to 30 degrees), and the light enters the flat surface at such an angle.

Further, there is also light that does not hit the flat surface but enters the scattering reflection surface ahead of the flat surface. Light incident on the scattering reflection surface is randomly scattered by the scattering reflection surface and travels toward the display surface. Further, there is light that is reflected on the flat surface or the scattering reflection surface and then travels toward the display surface after being reflected inside the box-shaped body.

As described above, since the light emitted from the LED is efficiently and directed to the display surface from a random direction, the display surface can have an extremely excellent and uniform brightness. In addition, since the light emitted from the LED efficiently reaches the display surface, the brightness of the display surface becomes extremely good.

The light emitted from the plurality of LEDs is
Since the light passes through the display surface in a mixed state, the color unevenness and the brightness unevenness of the individual LEDs are not reflected on the display surface.
This is very advantageous when using white LEDs. A white LED is obtained by adding a fluorescent agent that emits yellow light to a blue LED, and the color of an element serving as a light source (more precisely, a light emitting diode) is blue. The blue light is used to excite the fluorescent agent to emit yellow light, and white light is obtained through its synthesis.
Color unevenness (for example, blue wins or pinkish)
At present, it is extremely difficult to eliminate the color unevenness. For this reason, when the light of the white LED is directly applied to the display surface, the emission color of each LED is directly reflected on the display surface, and the white color is not uniform.

However, according to the configuration of claim 4 (the same applies to the configuration of claim 3), the light emitted from the plurality of LEDs is mixed and reaches the display surface, so that the color unevenness and brightness unevenness of each LED are reduced. It is not reflected on the display surface, and, for example, a very uniform white display without unevenness of brightness is realized. Needless to say, the same effect of equalization can be obtained without using a white LED.

According to a fifth aspect of the present invention, in the display device of the fourth aspect, the scattering reflection surface includes an inclined surface whose angle with the optical axis of the light emitting diode is obtuse on the display surface side. Therefore, for example, light near the optical axis of the LED can be scattered on the inclined surface and can be favorably reflected toward the display surface. Further, light reflected on the flat surface can also be scattered on the inclined surface and reflected well in the direction of the display surface. As a result, the brightness of the display surface can be further improved.

The entire scattering / reflecting surface may be an inclined surface, or only a part thereof may be an inclined surface. The inclined surface may be a flat surface, a curved surface, or a combination of a flat surface and a curved surface, for example, as long as light near the optical axis of the LED can be directed toward the display surface.

[0017]

Next, an embodiment of the present invention will be described with reference to an embodiment of the present invention.

[0018]

[Embodiment 1] This embodiment is an example in which the display device of the present invention is applied to a sign for a bus stop. As shown in FIG. 1, the bus stop sign 10 corresponding to the display device has a frame-shaped aluminum frame 12 corresponding to a frame member.

On both surfaces of the aluminum frame 12, a diffusion plate 13 made of white diffusion acrylic and a protection plate 14 made of transparent polycarbonate are respectively attached in two layers. That is, the box-shaped body 15 is formed by closing the opening of the aluminum frame 12 with the diffusion plate 13 and the protection plate 14.
Respectively correspond to a front member and a back member. In the case of this embodiment, a transparent film (corresponding to the display surface) in which the name of the stop or the name of the bus company is printed in a dark color system (for example, black or green) is sandwiched between the diffusion plate 13 and the protection plate 14. (Not shown). In addition, the name of the stop, the name of the bus company, and the like may be printed on the diffusion plate 13 or the protection plate 14, and in this case, the printing surface is the display surface.

Since the diffusion plate 13 is made of white diffusion acrylic, light is transmitted from one side to the other side, but the direction of light emitted after transmission is random (scattered).
Inside the box 15, a pair of printed circuit boards 16
(One set of three substrates 16) is attached to the long side of the aluminum frame 12 via the substrate holder 21, and each substrate 16 holds a large number of white light emitting diodes (LEDs) 18.

An LED 18 is attached to a hole (not shown) formed in the board 16 by penetrating a terminal pin, and power can be supplied to each LED 18 by a wiring (not shown). The LEDs 18 are all white LEDs of the same type. In this embodiment, NSPW50 of Nichia Corporation
0BS is used. Other white LEDs include NSPW510BS, NSPW300BS, NSP
W312BS, NSPW310BS, etc. can also be used. These LEDs 18 are all arranged with the optical axis perpendicular to the substrate 16, that is, in the direction parallel to the diffusion plate 13 and the protection plate 14.

A pair of scattering plates 20, both ends of which are held by a substrate holder 21, are arranged so as to block the LED 18 and the diffusion plate 13. The scattering plate 20 is formed by printing a white pigment (for example, titanium oxide powder) on one side of a transparent polycarbonate plate, and transmits light from one side to the other side. However, since the transmitted light hits the white pigment and is reflected, the direction of the emitted light is random (scattered) even if the directions of the incident light are aligned.

The base of the scattering plate 20 (near the substrate holder 21)
Is parallel to the optical axis of the LED 18, but the central portion is bent in a chevron and has an inclined surface 20 in a direction intersecting the optical axis of the LED 18.
a is formed. Although the bus stop sign 10 is used, for example, attached to a support, illustration and description of the support and the like are omitted.

In this bus stop sign 10, the scattering plate 2
0 is an inclined surface 20 at which the angle between the LED 18 and the optical axis is an acute angle.
a, almost all of the light emitted from the LED 18 (spreads in a conical shape with the optical axis as the center. The amount of light is mostly near the optical axis) hits the inclined surface 20a.

A part of the light hitting the inclined surface 20a passes through the scattering plate 20 as it is, and the rest is reflected by the inclined surface 20a and travels to the other (counter) scattering plate 20. Since the angle between the optical axis of the LED 18 and the inclined surface 20a is an acute angle, the light that is reflected and travels toward the scatter plate 20 on the other side is located at the center of the diffusion plate 13 and the protection plate 14 (around the vertical center line). Heading. Then, the light passes through the scattering plate 20 of the other party. Some of the light is reflected here, but such light will eventually be
Through.

The light transmitted through the scattering plate 20 is randomly scattered here and travels to the diffusion plate 13. The light incident on the diffusion plate 13 is also randomly scattered here,
The light passes through the transparent film sandwiched between the protective film 14 and the protective plate 14, and further passes through the protective plate 14 and is radiated to the outside. When the light passes through the transparent film, a part of the light is absorbed by the stop name or the like printed thereon, so that the stop name or the like is clearly displayed.

The light incident on the scattering plate 20 is incident on the inclined surface 20a.
Is moved to the center by the action of, so that the center is better prevented from becoming relatively darker (than the portion near the LED 18). Also, the light is randomly scattered by the scattering plate 20.
As a result, the intensity distribution of the light incident on the diffusion plate 13 is substantially uniform over the entire area of the diffusion plate 13.

The light radiated from the diffusion plate 13 is
It transmits through a transparent film, which is a display surface, from a random direction and with a substantially uniform intensity distribution, and clearly displays a stop name and the like printed thereon. Since the direction at which the light originating from the LED 18 passes through the display surface becomes random,
The display surface, that is, the name of the stop, etc., can be made extremely excellent in uniform brightness.

Further, the number of the LEDs 18 is extremely small as compared with a case where the optical axes are perpendicular to the display surface and the scattering plate 13, for example, in a matrix. Further, since the light emitted from the many LEDs 18 is mixed and reaches the display surface through the scattering plate 13, the color unevenness and brightness unevenness of the individual LEDs 18 are not reflected on the display surface, and the uniform white color is obtained. Light is applied to the display surface, and there is no uneven brightness.

[0030]

Embodiment 2 This embodiment is an example in which the display device of the present invention is applied to a road sign. As shown in FIG.
Numeral 0 is provided with an aluminum peripheral wall 51 corresponding to a frame member, an aluminum back member 53 is mounted on the back side thereof, and a display plate 56 and a scattering plate 54 are mounted on the front side in an overlapping manner. .

The display panel 56 is made of transparent polycarbonate.
The central red area 58 and the outer edge red area 62 shown in FIG. 3 are printed in red on the back surface (the surface on the side of the scattering plate 54).
The letters "stop" (illustrated in black but actually transparent) and the white area 60 around the central red area 58 are not printed, and this part is transparent with the material of the transparent polycarbonate as it is.

The scattering plate 54 is a transparent polycarbonate plate, and its surface (the surface on the display plate 56 side) has a side of about 3 mm.
The reflection area of the square is printed in a checkered pattern, and the reflection area and the transmission area are in a ratio of approximately 50:50, the reflection / transmission surface, and the back surface is printed with a white pigment (titanium oxide powder in this embodiment). It is a diffusion surface. For this reason, the character “STOP” and the white area 60 on the display panel 56 appear white.

A housing 55 is housed inside a box 52 composed of a peripheral wall 51, a back member 53, a display plate 56 and a scattering plate 54. The housing 55 is made of white polycarbonate and includes an outer peripheral groove 57 along the outer periphery, a central concave portion 59 provided from the center to the upper part, a flat portion 61 formed between the outer peripheral groove 57 and the central concave portion 59, and a nut chamber 63. The shape is uneven. The tip of a bolt standing on the back member 53 and penetrating through the spacer reaches the nut chamber 63, and the nut in the nut chamber 63 is tightened to the bolt, whereby the housing 55 is attached to the back member 53.

The central recess 59 is substantially rectangular, and the display plate 56
Is located behind the word "stop" when joined. As shown in FIGS. 2 and 4, a printed board 67 is attached to upper and lower inner walls 65 connected to the flat portion 61. An LED 69 is attached to the board 67 by penetrating a terminal pin through a hole (not shown) formed in the board 67, and power can be supplied to each LED 69 by a wiring (not shown).

The LEDs 69 are all the same type of white LEDs. In this embodiment, NSPW50 of Nichia Corporation
0BS is used. Other white LEDs include NSPW510BS, NSPW300BS, NSP
W312BS, NSPW310BS, etc. can also be used.

Each of the LEDs 69 is arranged with the optical axis perpendicular to the substrate 67, that is, in the direction parallel to the display panel 56. The central recess 59 has upper and lower inclined surfaces 71.
Is formed. Yamabe 7
The ridge line 3 is in the horizontal direction (perpendicular to the optical axis of the LED 69),
The angle between the inclined surface 71 and the optical axis C of the LED 69 is determined by the display
The angle is set to an obtuse angle on the side, and an acute angle (about 30 degrees in this example) on the inclined surface 71 side. Further, a flat surface 75 is provided between the inner wall 65 and the inclined surface 71.

As shown in FIG. 2, in the outer edge groove 57, two LEDs 69 facing each other are held on a substrate (not shown), and three sets of LEDs 69 are arranged on each side. On each side of the outer edge groove 57, a pair of inclined surfaces 7 similar to the peak 73 in the central recess 59 is provided at a position between the LEDs 69 facing each other.
7 and a flat surface 81 provided on both sides thereof. The angle between the inclined surface 77 and the optical axis of the LED 69 is set in the same manner as the inclined surface 71.

As shown in FIG. 3, the character "STOP" is described in the center of the display panel 56. As described above, the character "STOP" is located at the position corresponding to the central concave portion 59, and the central red region is displayed. 58, white area 60 and outer edge red area 62
Correspond to the flat portion 61 and the outer edge groove 57, respectively.

The road sign 50 is used, for example, attached to a column, but illustration and description of the column and the like are omitted. The LED 69 is not turned on in the daytime or the like on the road sign 50, and the character of "stop" is displayed by the outside light (usually sunlight) being reflected by the display panel 56.

On the other hand, when it is dark at night or in rainy weather, LE
D69 is turned on. The optical path of the light emitted from the LED 69 in that case will be described with reference to FIG. The light from the LED 69 spreads conically around the optical axis C. However, the amount of light increases near the optical axis C and decreases as the distance from the vicinity increases.

Assuming such a light cone, the light L1 near the side surface is reflected by the flat surface 75,
It goes to the scattering plate 54. The light L2 closer to the optical axis C and the light L3 near the optical axis C hit the inclined surface 71. There is also light that is reflected by the flat surface 75 and then hits the inclined surface 71. In any case, the light that hits the inclined surface 71 is scattered and reflected here and goes to the scattering plate 54. Note that FIG. 4 shows that the lights L2 and L3 are scattered at one point in multiple directions, but this is for the sake of simplicity.
In practice, the direction of reflection varies depending on the slight difference in the incident position and angle of incidence, resulting in scattered reflection.

Further, there is also light L4 which goes directly to the scattering plate 54 without going to the flat surface 75 or the inclined surface 71. Some light is reflected by the inner wall 65 and the like, and any of those light is reflected directly or by the flat surface 75 or the inclined surface 77 toward the scattering plate 54. That is, most of the light emitted from the LED 69 goes to the scattering plate 54.

The light incident on the scattering plate 54 is scattered and radiated in a random direction, and is transmitted through the display plate 56 and radiated to the outside. It can be clearly displayed. Although not shown, most of the light of the LEDs 69 arranged in the outer peripheral groove 57 is also directed toward the white area 60 of the display panel 56 by the function of the inclined surface 77 and the flat surface 81 similar to the above, and the light is clarified. indicate.

As described above, the light radiated from the LED 69 is directed to the display panel 56 and transmitted therethrough very efficiently, so that the characters "stop" printed on the display panel 56 can be very well and uniformly. Brightness can be adjusted. That is, the number of the LEDs 69 is extremely small as compared with a case where the optical axes C of the LEDs 69 are arranged in a matrix in a direction perpendicular to the display plate 56, for example.

The direction of light traveling toward the display panel 56 is
1 and the flat surface 75 (the inclined surface 77 and the flat surface 81) work, and a large number of LEDs 6 are arranged in random directions.
9 reach the display panel 56 in a mixed state, the color unevenness and brightness unevenness of the individual LEDs 69 are not reflected on the display panel 56, and extremely uniform white light is applied to the display panel 56. Irradiation and no light and dark unevenness.

Further, in this embodiment, since the display plate 56 also serves as the display surface, no member (a plate material, a sheet, a film, etc.) for forming the display surface is required, and the structure is simplified. The reason why the surface of the scattering plate 54 is a reflection / transmission surface is as follows.
For the following reasons. For example, there is a possibility that the LED 69 is not turned on at night due to a failure of the lighting circuit of the LED 69 or a power failure. In this case, when the road sign 50 is illuminated by the headlights of the automobile, the light of the headlights is reflected in the reflection area. The reflected light passes through the display panel 56 and reaches the automobile, that is, the driver, and clearly displays the word "stop".
Since the small-sized reflection area and the transmission area are arranged at a ratio of approximately 50:50, for example, at a distance of 150 m to 250 m, it looks as if the reflected light is emitted from the entire area of the road sign 50.

As described above, the embodiments of the present invention have been described with reference to the examples. However, the embodiments of the present invention are not limited to these examples, and can take various forms. For example, in the embodiment, white polycarbonate is used as the scattering reflection surface. However, as the scattering reflection surface, white or light-colored paper, paper or a plastic plate on which white or light-colored pigment is printed can be adopted. Further, the scattering / reflecting surface does not need to be an inclined surface, and may be parallel to the optical axis of the LED similarly to the flat surface.

As the materials (polycarbonate, acrylic, aluminum, etc.) used in the above two examples, other materials having the same functions (physical properties) can be used. For example, a resin plate such as vinyl chloride can be used instead of acrylic or polycarbonate.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the structure of a bus stop sign according to a first embodiment, (a) is a front view in a state where a protection plate, a diffusion plate and a scattering plate on one side are removed, (b) is a longitudinal sectional view, and (c). ) Is a cross-sectional view.

FIG. 2 is an explanatory view of a main body of a road sign according to a second embodiment, where (a) is a front view and (b) is a longitudinal sectional view.

FIG. 3 is a front view of a display board of a road sign according to a second embodiment.

FIG. 4 is an explanatory diagram of an optical path in a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bus stop sign (display device) 12 Aluminum frame (frame member) 14 Display plate (display surface, front member, back member) 15 Box body 16 Substrate 18 LED (light emitting diode) 20 Scattering plate 50 Road sign (display device) 51 Peripheral wall (frame member) 53 Back member 55 Box-shaped body 56 Display plate (display surface, front member) 67 Substrate 69 LED (light emitting diode) 71, 77 Inclined surface (scattering and reflecting surface) 75, 81 Flat surface C Optical axis

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toru Furuta 281-1, Imafuku, Kinjocho, Naga-gun, Shimane Prefecture F term in Shimane Electronics Imafuku Seisakusho (reference) 2D064 AA11 AA22 BA02 CA03 DA01 DA11 EA02 EB05 EB35 5C096 AA05 BA01 BB07 CA32 CB01 CC06 CC21 CE06 CF00 FA03

Claims (5)

[Claims] 1. A box-shaped body comprising a frame member, a front member for closing one opening of the frame member, and a back member arranged to face the front member, and a box-shaped body formed inside the box-shaped body. In a display device including a light emitting diode to be disposed and a display surface for displaying information by transmitting light derived from the light emitting diode, the light emitting diode is disposed in a direction in which an optical axis thereof is parallel to the display surface. A display device characterized by the above-mentioned. 2. The display device according to claim 1, wherein the display surface is provided on the front member or the back member. 3. The display device according to claim 1, wherein a scattering plate for scattering transmitted light is provided between the light emitting diode and the display surface. 4. The display device according to claim 1, wherein the display surface is provided only on the front member, and the display surface is provided on the back member side along a direction parallel to an optical axis of the light emitting diode. A display device comprising: a flat surface; and a scattering / reflecting surface disposed farther from the light emitting diode than the flat surface. 5. The display device according to claim 4, wherein the scattering reflection surface includes an inclined surface whose angle with the optical axis of the light emitting diode is obtuse on the display surface side. apparatus.