JP3624760B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device suitable for an indicator lamp, an illumination display unit of an illuminated push button switch, and the like.
[0002]
[Prior art]
FIG. 16 is a configuration diagram of a conventional display device, in which 20 is a cap made of a substantially transparent resin material, 21 is a name plate on which required characters are engraved or printed, and 22 is a lens with a lens. A diffusion plate for diffusing light emitted from the LED 23, a cap holder 24 for fitting the cap 20 to hold the name plate 21 and the diffusion plate 22, an LED holder 25 for fixing the LED 23, 26 an LED substrate, 27 Is a mounting panel to which the display device is mounted by a holding metal fitting 28, 29 is a case, and 30 is an external electrode. In this conventional example, the LEDs 23 with a lens are arranged in two rows of four each along the longitudinal direction (perpendicular to the paper surface) of the cap 20.
[0003]
In such a display device, when a voltage is applied to the external electrode 30, the LED 23 emits light through the LED substrate 26, and the light is diffused and transmitted through the diffusion plate 22 to be illuminated.
[0004]
As shown in FIG. 17A, the LED 23 with a lens shown in FIG. 17B has a directional characteristic that emits a lot of light forward, and thus the luminance in the display unit of the display device of FIG. In the distribution, as shown in FIG. 18, the luminance at the position corresponding to the LED 23 is high.
[0005]
FIG. 19 is a diagram showing a connection state in the case where divided lighting is performed for each column of four LEDs 23 using such a conventional display device. Reference numerals 31 and 32 are mounted on the LED board 26 described above. Current limiting resistor. An operation of applying a voltage between the first and second electrodes 33-1 and 33-2 to light the four LEDs 23-1 in one row with the first emission color, and the first and third electrodes By separately applying the voltage between 33-1 and 33-3 and lighting the four LEDs 23-2 in the other row with the second emission color, the two-color split lighting is performed. be able to.
[0006]
[Problems to be solved by the invention]
Generally, in order to improve the visibility in the display unit, it is necessary to increase the luminance of the display unit and make the luminance uniform.
[0007]
In addition, in a display device attached to an attachment panel or the like, there is a demand for a smaller and shorter body that is shortened in the thickness direction of the attachment panel.
[0008]
However, in the above-described conventional display device, when the distance between the diffusion plate 22 and the LED 23 is shortened in order to increase the luminance of the display unit and further reduce the size, the luminance of the display device is increased as shown in FIG. There is a problem that the difference between the high portion and the low portion is further increased, luminance non-uniformity is increased, and visibility is lowered.
[0009]
In addition, in the case of divided lighting, visibility can be improved by aligning the luminance between LEDs of different colors, but in general, if the emission color of the LEDs is different, the amount of voltage drop at the LEDs is reduced. In order to make the brightness uniform, as shown in FIG. 19, the first current limiting resistor 31 corresponding to the first emission color LED 23-1 and the second emission color LED 23-2 are provided. It is necessary to individually set the resistance value with the corresponding second current limiting resistor 32 in accordance with the LEDs 23-1 and 23-2 having different emission colors. It is necessary to prepare LED substrates having different resistance values, and there is a problem that the management cost increases due to an increase in the number of components to be managed.
[0010]
The present invention has been made paying attention to such a point, and has as its main purpose to improve the visibility of the display device, and further provides a display device that can cope with divided lighting at low cost. With the goal.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0012]
That is, the present invention relates to a display device that illuminates the display surface with light from a light source disposed on the back side of the display surface, wherein the light source is a surface-mounted LED, and on the back side of the display surface A diffusion member for diffusing and transmitting light is disposed, and the two LED substrates on which the LEDs are mounted are arranged on the display surface so that the emission direction of the LEDs on the respective substrates is parallel to the display surface. The reflective surface that is vertically installed on the LED holder so that the non-LED mounting surfaces oppose each other and reflects the emitted light from the LED toward the diffusing member is inclined with respect to the LED substrate. Then, the LED holder is provided, and the reflection surface is configured to scatter and reflect the emitted light.
[0014]
According to the present invention, the emission direction of the light source, so as to parallel to the display surface and the outgoing light to be reflected by the reflecting surface, so out Shako is to be illuminated indirectly display surface, out Compared to the conventional example in which the display surface is directly illuminated by the incident light, the luminance unevenness on the display surface is reduced and the visibility is improved. In addition, since the luminance unevenness is small, the light source can be arranged closer to the display surface, and the display device can be downsized.
[0016]
According to the present invention, since a surface-mounted LED, a so-called chip LED, is used as a light source, it is possible to increase the luminance, reduce the luminance unevenness as described above, and further, it is sufficiently scattered and reflected by the reflecting surface. Therefore, the transmittance of the diffusing member can be set high, and higher brightness can be achieved.
[0018]
According to the present invention, since the main emitted light from the LED mounted on the LED substrate substantially perpendicular to the display surface is scattered and reflected by the inclined reflecting surface toward the diffusing member, uneven luminance on the display surface is reduced. As a result, the luminance can be made uniform and the luminance can be increased.
[0019]
Furthermore, in a preferred embodiment of the present invention, a light shielding member is disposed on an optical path in which emitted light from the LED goes directly to the diffusing member.
[0020]
According to the present invention, since the direct light reaching the display surface is shielded by the light shielding member, the ratio between the direct light that directly illuminates the display surface and the indirect light that is reflected by the reflective surface and illuminates can be changed. Can be further reduced.
[0021]
In another embodiment of the present invention, a base substrate for holding the LED substrate is provided, and a current limiting resistor for limiting a current to the LED is mounted on each of the substrates.
[0022]
According to the present invention, the LED substrate can be held by the base substrate, and by mounting the main current limiting resistor on the base substrate, it is possible to reduce the influence of heat generated by the current limiting resistor on the LEDs of the LED substrate.
[0023]
Furthermore, in another embodiment of the present invention, a plurality of the LED substrates are provided, and LEDs having different emission wavelengths are mounted for each LED substrate, and current limiting resistors are provided so that the power consumption in each LED substrate is substantially equal. The resistance value is set.
[0024]
According to the present invention, since the power consumption of each LED board on which LEDs of different emission wavelengths are mounted is substantially equal, when using an LED board with a different emission color, it is only necessary to replace the LED board while leaving the base board as it is.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
(Embodiment 1)
FIG. 1 is a sectional view of a display device according to the present invention, and FIG. 2 is an exploded perspective view thereof.
[0027]
In these figures, 1 is a cap made of a substantially transparent resin material, 2 is a light transmitting material in which required characters such as “ON”, “OFF”, “operation”, and “abnormal” are formed by engraving or printing. The name plate 3 made of the above material is a semi-light transmissive diffuser that diffuses light from the LED 4 to reduce unevenness of brightness, and coloring the diffuser 3 enables color illumination. . Further, the diffusing plate 3 has a satin-like unevenness on the surface in order to increase the diffusion of light. Generally, when the diffusion of light on the diffusion plate is increased, the light transmittance is lowered.
[0028]
Reference numeral 5 denotes a cap holder that fits the cap 1 and holds the name plate 2 and the diffusing plate 3. The cap holder 5 is made of a substantially white material that scatters and reflects light or a material that is coated in a substantially white color. The cap 1, the name plate 2 and the diffusion plate 3 constitute a display unit.
[0029]
6 is a mounting panel to which the display device is attached, 7 is a holding metal fitting that is attached to the case 8 to prevent the display device from falling off the opening of the mounting panel 6, and 9 is an external electrode that pulls out the internal electrode 10 to the outside. is there.
[0030]
The display device of this embodiment is configured as follows in order to reduce luminance unevenness on the front surface of the cap 1 serving as a display surface and to improve visibility by increasing the luminance.
[0031]
That is, in this embodiment, in order to increase the luminance of the display unit, a surface-mounted LED 4, that is, a so-called chip LED 4 is used as a light source. As shown in FIG. 3A, the LED 4 has a wide directivity characteristic compared with the conventional LED 23 with a lens. As shown in the relative luminance distribution on the LED front plane in FIG. The brightness in the vicinity is sufficiently high. Therefore, in the configuration in which the diffusing plate 3 is arranged in front of the LED 4, uneven brightness occurs on the display surface.
[0032]
Therefore, in this embodiment, in order to reduce luminance unevenness, the main emission direction of the LED 4 is not a direction (upward in FIG. 1) toward the display surface of the display unit, but a direction substantially parallel to the display surface. For this reason, the two LED substrates 11 on which the LEDs 4 are respectively mounted are erected substantially vertically with respect to the display surface and are held by the LED holders 12, respectively. It arrange | positions so that the inner wall 12-1 may be opposed. On each LED substrate 11, four LEDs 4 are mounted, and current limiting resistors 13 that limit the drive current to the LEDs 4 are mounted.
[0033]
The LED holder 12 scatters and reflects (diffusely reflects) the light emitted from the LED 4, and is made of a substantially white material or a material painted in a substantially white color. The inner wall 12-1 facing the LED 2. Is a reflection surface, and this reflection surface is an inclined surface so as to guide the light emitted from the LED 4 to the diffusion plate 3 of the display unit. By setting the inclination angle, it is possible to change the amount of light that can be guided to the diffusion plate 3 by scattering and reflecting the light emitted from the LED 4.
[0034]
The LED substrate 11 on which the LED 4 is mounted has a portion other than the LED mounting portion painted in white by, for example, silk screen printing so that light can be scattered and reflected. If a ceramic substrate is used as the LED substrate 11, there is no need for painting because the substrate color is white.
[0035]
Next, the principle of uniforming and increasing the luminance in the display device having the above configuration will be described in more detail with reference to FIG.
[0036]
A circle A in FIG. 5 indicates the directivity characteristics of the reflected light when one light beam emitted from the LED 4 reaches the scattering reflection surface of the inner wall 12-1 of the LED holder 12.
[0037]
The main emitted light emitted from the LED 4 is scattered and reflected by the scattering reflection surface of the inner wall 12-1 of the LED holder 12 and reaches the diffusion plate 3. Further, a part of the emitted light emitted upward or obliquely upward from the LED 4 reaches the diffusion plate 3 directly. Of the scattered and reflected light, the light that reaches the other scattering reflection surfaces of the LED substrate 11 and the LED holder 12 is scattered and reflected again, which contributes to uniformly illuminating the display unit.
[0038]
As described above, since most of the light reaching the diffusion plate 3 is scattered and reflected indirect light, the LED light passing through the diffusion plate 3 is shown in the relative luminance distribution example B above the diffusion plate 3. Further, the luminance unevenness can be reduced and the display portion can be illuminated. At this time, if the light reaching the diffusion plate 3 is not sufficiently diffused, it is necessary to further diffuse the light with the diffusion plate 3, so that the transmittance of the diffusion plate 3 cannot be set high, and the display In this embodiment, the light reaching the diffusion plate 3 is sufficiently scattered by the scattering reflection surface. Therefore, the transmittance of the diffusion plate 3 is set high. In this case, uniformity in luminance can be obtained, and high luminance can be obtained in the display unit.
[0039]
FIG. 6 is a diagram showing the luminance distribution of the display unit of the display device of this embodiment, and it can be seen that the luminance unevenness is greatly reduced as compared with the conventional example of FIG.
[0040]
In this embodiment, the LEDs 4 are mounted on the two substrates 11, respectively. However, as another embodiment of the present invention, the LEDs 4 may be mounted on both surfaces of one substrate. Further, by changing the emission color of the LED 4 to be mounted for each substrate, a two-color emission display device can be easily realized. Furthermore, if the number of substrates is four, a display device that emits four colors can be easily realized.
[0041]
(Embodiment 2)
FIG. 7 is a cross-sectional view of a main part of the embodiment of the reference example , and parts corresponding to the above-described embodiment are denoted by the same reference numerals.
[0042]
In the above embodiment, the main emission direction of the LED 4 is a direction perpendicular to the mounting surface (substrate surface). However, in this embodiment, as shown in FIG. The LED 4a having a main emission direction in a direction parallel to) is used.
[0043]
According to this embodiment, the distance between the diffusing plate 3 and the LED 4a can be increased, more favorable diffused light can be obtained, and luminance unevenness can be further reduced.
[0044]
Moreover, since it is not necessary to stand the LED board 11 unlike the above-mentioned embodiment, a display apparatus can be shortened in the thickness direction (up-down direction of FIG. 7) of a mounting panel, and a small-sized body is shortened. It is effective in planning.
[0045]
(Embodiment 3)
FIG. 9 is a cross-sectional view of a main part of still another embodiment of the present invention, and parts corresponding to those of the above-described first embodiment are denoted by the same reference numerals.
[0046]
In the above-described first embodiment, the inner wall 12-1 of the LED holder 12 made of a reflecting surface for scattering reflected light emitted from the LED 4, Domo Re only was plane, in this embodiment, the inner wall 12 of the LED holder 12b -1 is a curved surface. Thus, by making the inner wall 12b-1 of the LED holder 12b serving as a scattering reflection surface a curved surface, the degree of scattering of the scattered and reflected light can be increased, Scattered light can be obtained.
[0047]
In this embodiment, although the curved surface is formed in a convex shape, it may be formed in a concave shape as another embodiment of the present invention.
[0048]
(Embodiment 4)
FIG. 10 is a cross-sectional view of a main part of another embodiment of the present invention, and parts corresponding to the above-described embodiment are denoted by the same reference numerals.
[0049]
In this embodiment, a light shielding member 14 that shields the emitted light from the LED 4 is provided on the upper end of the LED substrate 11 on the optical path of the emitted light from the LED 4 directly toward the diffusion plate 3, in this example, the LED substrate 11. Are arranged along the longitudinal direction (perpendicular to the paper surface).
[0050]
By this light shielding member 14, the ratio of the indirect light reaching the diffusion plate 3 scattered and reflected by the inner wall 12-1 of the LED holder 12 and the direct light reaching the diffusion plate 3 directly from the LED 4 can be changed. Good scattered light can be obtained.
[0051]
By using a chip resistor, a chip capacitor, or a dummy surface mount component as the light shielding member 14, the light shielding member 14 can be mounted simultaneously with the mounting of the LED 4, and the light shielding member 14 can be realized at a low cost.
[0052]
(Embodiment 5)
FIG. 11 is an exploded perspective view of still another embodiment of the present invention, and FIG. 12 is a cross-sectional view of the main part thereof. Parts corresponding to those of the first embodiment are denoted by the same reference numerals. Is attached.
[0053]
In this embodiment, a base substrate 15 that holds two LED substrates 11 b is provided, and the LED substrate 11 b and the electrode 10 a are connected via the base substrate 15. The base substrate 15 has two slit-like fitting holes 16 extending in the longitudinal direction for attaching the two LED substrates 11b, and the lower end of the LED substrate 11b is inserted into the fitting holes 16. The parts are inserted and fitted, soldered from the back side, and held as shown in FIG.
[0054]
Current limiting resistors 17-1 and 17-2 are mounted on the back surface of the base substrate 15, and current limiting resistors 13-1 and 13-2 that match the characteristics of the LED 4 are also mounted on each LED substrate 11 b. Has been.
[0055]
FIG. 14 is a diagram showing a connection state between the LED 4 of this embodiment and the current limiting resistors 13-1, 13-2, 17-1, 17-2, and FIG. The case (b) shows the case of split lighting.
[0056]
In FIG. 2A, all LEDs 4 can be turned on by applying a voltage between the first and second electrodes 10a-1 and 10a-2 to flow a current.
[0057]
In FIG. 5B, a voltage is applied between the first and second electrodes 10a-1 and 10a-2 to light up the four LEDs 4-1 in one column with the first emission color, It is possible to perform split lighting of two colors by applying a voltage between the first and third electrodes 10a-1 and 10a-3 to light the four LEDs 4-2 in the other row with the second emission color. .
[0058]
As shown in FIG. 14, the current limiting resistors 13-1 and 13-2 on the LED substrate 11b and the current limiting resistors 17-1 and 17-2 on the base substrate 15 are connected in series. .
[0059]
The voltage drop in each LED board 11b is set to be approximately the same by the selection of the current limiting resistor, that is, the power consumption in each LED board 11b is set to be approximately equal, so that the LED boards having different emission colors. The same base substrate 15 can be used when mounting 11b.
[0060]
When split lighting is used and no current limiting resistor is provided on the LED substrate, base substrates having different resistance values for the current limiting resistors 17-1 and 17-2 to be mounted are prepared for all combinations of emission colors. Therefore, as in the conventional example of FIG. 19 described above, the part management cost increases.
[0061]
For example, when manufacturing a display device capable of two-part lighting using four colors of green, red, white, and orange LEDs, the types of substrates to be prepared include 4 × 4 = 16, including two-part lighting of the same color. Twenty kinds of substrates, that is, the base substrate 15 and four kinds of LED substrates 11b are required.
[0062]
On the other hand, in this embodiment, since the magnitude of the voltage drop in the LED substrate 11b is set to be equal, the types of the substrate are one type of base substrate 15 and four types of LED substrates. A total of five types of substrates 11b are in time.
[0063]
For this reason, it is possible to greatly reduce the types of components to be managed.
[0064]
In this embodiment, the number of divisions is described as two divisions, but it goes without saying that the same effect can be obtained even if the number of divisions is increased to three divisions or four divisions.
[0065]
Further, as the number of divisions increases, the effect of reducing the number of substrates increases.
[0066]
(Embodiment 6)
FIG. 15 is a diagram showing a connection state according to still another embodiment of the present invention, and portions corresponding to FIG. 14B are denoted by the same reference numerals.
[0067]
The difference from the above-described embodiment is that two LED boards 11b connected in parallel are connected in series with the current limiting resistor 17 on the base board 15.
[0068]
In addition to a method of dividing the illumination unit of the display device into two parts and lighting them individually, there is a method of causing the LEDs of two colors 4-1 and 4-2 to emit light in a mixed color and emit light in the third color.
[0069]
When light is emitted in the third color, since two types of colors are lit simultaneously, normally, the third luminescent color has a luminance that is approximately twice that of a single color. For this reason, there is a problem that the difference in luminance is large between the third emission color and the lighting of the single color LED, and the visibility at the time of the single color lighting is relatively lowered.
[0070]
In this embodiment, when the two types of LEDs 4-1 and 4-2 are simultaneously turned on to emit light in the third color, the drive currents flowing through the two types of LEDs 4-1 and 4-2 are determined by the base substrate 15. It becomes smaller than the time of monochromatic lighting limited by the upper current limiting resistor 17. For this reason, it is possible to reduce the luminance difference between the single color lighting and the third color lighting, and it is possible to realize three-color light emission without reducing the visibility.
[0071]
(Other embodiments)
You may combine each above-mentioned embodiment suitably.
[0072]
The display device of the present invention may be used as an illumination display unit (operation unit) of an illuminated push button switch that illuminates according to a pressing operation.
[0073]
【The invention's effect】
According to the present invention As is apparent from the above description, the output morphism direction of the light source, since by varying the direction toward the display surface and so as to illuminate the indirect display surface, Direct display surface in Shako Compared with the conventional example in which the light is illuminated, the luminance unevenness on the display surface is reduced and the visibility is improved. In addition, since the luminance unevenness is small, the light source can be arranged closer to the display surface, and the display device can be downsized.
[0074]
Further, according to the present invention, since the surface mount type LED is used as the light source, it is possible to increase the luminance, reduce the luminance unevenness as described above, and further, it is sufficiently scattered and reflected by the reflecting surface. Since it is diffused, the transmittance of the diffusing member can be set high, and higher brightness can be achieved.
[0075]
Furthermore, according to the present invention, since the power consumption of each LED board on which LEDs of different emission wavelengths are mounted is substantially equal, when using an LED board having a different emission color, the base board remains unchanged and only the LED board is replaced. What is necessary is that the number of substrates to be managed can be reduced compared with the conventional example, and the management cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a display device according to the present invention.
2 is a divided perspective view of the display device of FIG. 1. FIG.
FIG. 3 is a diagram showing the directivity and appearance of the LED of FIG.
4 is a diagram showing a relative luminance distribution on the front surface of the LED of FIG. 3; FIG.
FIG. 5 is a diagram for explaining the principle of uniforming and increasing luminance.
6 is a diagram showing a relative luminance distribution of a display unit of the display device of FIG. 1. FIG.
FIG. 7 is a cross-sectional view of a main part of an embodiment of a reference example .
FIG. 8 is a view showing main emission directions of the LED of FIG. 7;
FIG. 9 is a cross-sectional view of a main part of still another embodiment of the present invention.
FIG. 10 is a cross-sectional view of a main part of another embodiment of the present invention.
FIG. 11 is an exploded perspective view of a display device according to still another embodiment of the present invention.
12 is a sectional view of a main portion of the display device in FIG 11.
FIG. 13 is a perspective view showing a fitting state of the LED substrate and the base substrate.
FIG. 14 is a diagram illustrating a connection state between collective lighting and divided lighting.
FIG. 15 is a diagram showing a connection state according to still another embodiment of the present invention.
FIG. 16 is a cross-sectional view of a conventional display device.
17 is a diagram showing a luminance distribution of a display unit of the display device of FIG.
18 is a diagram showing a luminance distribution of a display unit of the display device of FIG.
19 is a diagram showing a connection state of split lighting of the display device of FIG.
[Explanation of symbols]
3 Diffuser 4, 4a LED
11, 11a, 11b LED substrate 12, 12a, 12b, 12c LED holder 14 Light shielding member 15 Base substrate

Claims (4)

In a display device that illuminates the display surface with light from a light source disposed on the back side of the display surface,
The light source is a surface-mounted LED, and a diffusion member that diffuses and transmits light is disposed on the back side of the display surface,
The two LED substrates each mounted with the LEDs are perpendicular to the display surface and the non-LED mounting surfaces face each other so that the LED emission direction of each substrate is parallel to the display surface. Standing on the LED holder back to back,
A reflective surface that reflects the emitted light from the LED so as to go toward the diffusing member is provided on the LED holder so as to be inclined with respect to the LED substrate,
The display device , wherein the reflection surface is configured to scatter and reflect the emitted light . Display device according to claim 1 wherein placing the light shielding member on an optical path directly toward the exit light is the diffusion member from the LED. The LED includes a base substrate for holding the substrate, wherein the LED substrate and the base substrate, a current limiting resistor that limits the current to the LED is the display device according to claim 1, wherein the mounted respectively. Together comprise a plurality of the LED substrate, each LED substrate, different emission wavelength LED are mounted, the display device according to claim 3, wherein setting the resistance value of the current limiting resistor so that the power consumption in each LED substrate becomes equal properly .

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