LED lighting devices

Abstract

To provide an LED lighting device that illuminates an object with equal output levels of green (G) and red (R), allowing the object's colors to be seen in their original hues, and enabling even illumination of fine details. [Solution] The configuration comprises an LED light-emitting section made of high-brightness white LEDs, a first reflecting section that reflects the light emitted from the LEDs of the LED light-emitting section in one direction, a lens disposed on the opening side of the front of the first reflecting section that concentrates or scatters light, a filter that absorbs light of a predetermined color from the light that has passed through the lens, a second reflecting section that reflects the light reflected by the filter back to the first reflecting section, a light guide provided on the opening side that emits the light reflected by the first reflecting section and the second reflecting section to the outside, and a space of a predetermined interval provided between the lens and the light guide.

Description

Technical Field

[0001] The present invention relates to an LED lighting device, and more particularly to an LED lighting device capable of performing lighting in which G (green) and R (red), which are axial lights with respect to a lighting object, are adjusted to the same output level.

Background Art

[0002] Typical conventional lighting devices include fluorescent lamps and LED lighting devices. In a fluorescent lamp, when an electric current is passed through an electrode to heat it, thermoelectrons are emitted from the electrode. The emitted thermoelectrons collide with mercury atoms in a glass tube to generate ultraviolet rays, and a fluorescent substance coated on the inner wall of the glass tube absorbs the ultraviolet rays and emits visible light as the emission principle.

[0003] In an LED lighting device, holes having a positive property and electrons having a negative property move in a semiconductor chip, collide with each other, and combine (recombine). When recombining, the energy of the electrons and holes becomes smaller than the energy they originally had, and the excess energy is emitted as light as the emission principle.

[0004] By the way, at the 5th Conference of the Parties to the Minamata Convention on Mercury, it was agreed to prohibit the manufacture, import, and export of straight tube fluorescent lamps by the end of 2027. Combined with the spherical & compact fluorescent lamps for which the prohibition of manufacture, import, and export by the end of 2026 has already been decided, the end of production of all general lighting fluorescent lamps is expected. Therefore, in the future, LED lighting devices will become the center as lighting devices.

[0005] Conventional LED lighting devices are based on sunlight in terms of their spectral characteristics. That is, their spectral characteristics (measuring the light emitted from a light source for each wavelength (spectroscopy) and representing the ratio of the energy of that light) aim for a color tone and color that conform to sunlight. Figure 4 shows the spectral distribution of sunlight (color rendering index (Ra): 99). A considerable number of instances of uneven illuminance distribution (peaks and valleys in the curve) can be observed for each color (R, G, and B), with R showing a particularly pronounced imbalance. Furthermore, it can be seen that not all wavelengths are uniform, but rather follow a continuous pattern of light → dark → light → dark.

[0006] On the other hand, Figure 5 is a spectral distribution diagram of a conventional high-color rendering (color rendering index (Ra): 97) LED lighting device. The characteristic curves also show uneven peaks for each color, the characteristics of B are exceptionally good, the maximum light emission points of G and R are shifted, and the gradation from the brightest to the darkest parts is partially reversed. Similarly, it can be seen that not all wavelengths are uniform, but rather there is a continuous pattern of light → dark → light → dark wavelengths. [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] Conventional LED lighting devices aim for spectral characteristics that are similar to those of sunlight, which has led to the following problems. (1) Sunlight (Ra99) has an uneven illuminance distribution for each of the R, G, and B colors (peaks and valleys in the curve), and R has a particularly significant imbalance with respect to G of the reference light. Therefore, even with LED lighting devices that conform to this, there is a problem in that the colors of objects that should be visible are perceived as having different hues and colors than they actually are. (2) Furthermore, conventional LED lighting devices are point light sources (the light source is a small point), which means that the light does not fall evenly on the object, making it impossible to examine the details. The characteristic curve of the high color rendering (Ra97) LED lighting device shown in Figure 3 also shows uneven peaks for each color, with the characteristic of B being outside the normal range, the maximum light emission points of G and R being misaligned, and the gradation from the brightest to the darkest areas being partially inverted, making it impossible to accurately verify the density of the colors. (3) In order to solve these two problems, one could supplement the lack of warm-colored LED light, but this would increase the weight, making the entire device large, complex, and expensive, thus making it unsuitable as a general lighting device.

[0008] Therefore, the object of the present invention is to provide an LED lighting device that illuminates an object with G (green) and R (red) output adjusted to the same degree, thereby allowing the color tones of the object to be seen to be perceived in their original colors, and that illuminates the object evenly, enabling detailed inspection.

[0009] To achieve the above objective, the present invention provides an LED lighting device comprising: an LED light-emitting section made of high-brightness white LEDs; a first reflecting section that reflects light emitted from the LEDs of the LED light-emitting section in one direction; a lens disposed on the opening side of the front of the first reflecting section that concentrates or scatters light; a filter that absorbs light of a predetermined color from the light that has passed through the lens; a second reflecting section that reflects the light reflected by the filter back to the first reflecting section; a light guide provided on the opening side that emits the light reflected by the first reflecting section and the second reflecting section to the outside; and a space of a predetermined interval provided between the lens and the light guide.

[0010] In the above configuration, the space is characterized by mixing light that is repeatedly reflected between the first reflecting part, the second reflecting part, and the light guide.

[0011] Furthermore, the filter is characterized by being a color filter that absorbs R-colored light. Effect of the invention

[0012] As the present invention is configured as described above, it produces the following effects and benefits. In other words, the light reflected by the first reflector passes through the lens, filter, and light guide and is emitted to the outside. However, some of the emitted light is reflected back into space within the light guide, and is then reflected again by the second reflector, its color is filtered out, and the reflection process repeats. This is known as the pumping phenomenon, where the light repeatedly travels back and forth within the light guide and is mixed.

[0013] This equalizes the light intensity of the GR, converting it into light that gradually attenuates from the maximum intensity to the minimum intensity. The mixed and gradually attenuated light then exits from the light-emitting surface through the light guide and is emitted from the underside of the LED lighting device.

[0014] Light emitted from a light-emitting surface forms a smooth curve without multiple emission peaks in a single wavelength range, similar to sunlight or high-color-rendering LEDs. When there are multiple emission peaks in the same wavelength range, the illuminance distribution is irregular, causing uneven illumination due to shadows in light intensity, making it impossible to accurately visualize the color and shape of an object.

[0015] In contrast, the LED lighting device of the present invention produces a smooth curve without multiple emission peaks in a single wavelength range. Therefore, the light that passes through the light guide 50 is converted into a surface light source and pure white light, allowing for accurate confirmation of the shape and color of an object. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view showing the configuration of the LED lighting device of the present invention. [Figure 2] This is a view of the LED lighting device of the present invention, as seen from the light-emitting surface side. [Figure 3] This is a spectral distribution diagram of the LED lighting device of the present invention. [Figure 4] This is a spectral distribution diagram of sunlight (Ra99). [Figure 5] This is a spectral distribution diagram of a conventional LED lighting device (Ra99). [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described below with reference to the drawings.

[0018] Figure 1 is a cross-sectional view showing the configuration of the LED lighting device of the present invention, and Figure 2 is a view of the LED lighting device of the present invention from the light-emitting surface side. As shown in Fig. 1, this LED lighting device includes an LED light-emitting part 10 composed of high-brightness white LEDs 2, a first reflecting part 11 that reflects the light emitted from the LEDs 2 of the LED light-emitting part 10 in one direction, a lens 30 disposed on the opening side of the front surface of the first reflecting part 11, a filter 40 that absorbs (cuts) light of a predetermined color among the light passing through the lens 30, a light guide 50 that guides the light passing through the filter 40 to the outside, and a second reflecting part 12 that reflects the light reflected by the filter 40 back to the first reflecting part 11.

[0019] In the above configuration, the first reflecting part 11 is curved toward the opening side of the front surface, and the LED light-emitting part 10 is disposed at the center of the curvature. The high-brightness white LED 2 to be disposed is a single LED.

[0020] The lens 30 is a convex meniscus lens with the center of the lens being thicker than the peripheral part, and it performs light condensation and scattering.

[0021] The high-brightness white LED 2 has a rated current value of about 350 mA and can pass a maximum current of 500 mA. Therefore, it can emit light with a brightness sufficient for use in flashlights, bicycle headlights, etc. As the rated current value of the high-brightness white LED 2, those with a value of 100 mA to 1000 mA can be applied, but considering power consumption, those with a value of 350 mA to 500 mA are desirable as they can obtain the required brightness.

[0022] The filter 40 is for absorbing light of a predetermined color, and in the present invention, it is a color filter that absorbs the R-color light emitted from the high-brightness white LED 2. As described above, since the R color has particularly unbalanced characteristics with respect to the G color of the reference light, in order to align the light quantity and spectral characteristics of the primary colors (R·G·B), the first reflecting part 11, the second reflecting part 12, and the filter 30 are used to absorb (cut) this prominent R color to the G color level.

[0023] Next, referring to Fig. 1, the behavior of light in the LED lighting device of the present invention will be described in detail. As shown in the figure, the light emitted by LED2 is emitted into the curved first reflector 11. The emitted light passes through the lens 30, and a portion of it passes through the filter 40 and light guide 50 before being emitted to the outside. The light reflected by the filter 40 passes through the lens 30 again in the second reflector 12 and enters the first reflector 11. In this way, the light is amplified and diffused to a stronger intensity by the lens 30.

[0024] Light reflected by the first reflector 11 passes through the lens 30, filter 40, and light guide 50 and is emitted to the outside. At this time, as shown in the enlarged cross section, a portion of the emitted light is reflected within the light guide 50 and returns to space 60, where it is reflected again by the second reflector 12, and the color is cut off by the filter 40, and the reflection is repeated. Due to the so-called pumping phenomenon, the light repeatedly moves back and forth within the light guide and is mixed.

[0025] This equalizes the light intensity of the GR, converting it into light that gradually attenuates from the maximum intensity to the minimum intensity. The mixed and gradually attenuated light then exits from the light-emitting surface through the light guide and is emitted from the underside of the LED lighting device.

[0026] When there are multiple emission peaks within the same wavelength range of color, the illuminance distribution is irregular, causing uneven illumination due to shadows in light intensity, making it impossible to accurately visualize the color and shape of an object.

[0027] In contrast, the LED lighting device of the present invention produces a smooth curve without multiple or more emission peaks in a single wavelength range. Therefore, the mixed-color light that passes through the light guide 50 is converted into a surface light source and pure white light, allowing for accurate confirmation of the shape and color of an object.

[0028] In the LED lighting device 1 of the present invention, the light-emitting surface is preferably about 15 mm to 50 mm in diameter, and it is preferable that the object be observed at a distance of 20 cm or more from the light-emitting surface.

[0029] The light intensity is equal to that of the green (G) color, resulting in a balanced spectral characteristic between the green and red (R) colors (referred to as pure white). By converting the light into rays that gradually attenuate from the point of maximum emission, the color tone and shape of the illuminated object can be visualized more clearly and in greater detail.

[0030] Figure 3 shows the spectral characteristics of a surface light source, pure white. The B color has a higher illuminance than the G and R colors, and at first glance, the spectral characteristics appear uneven. However, since the B color (yellow as its complementary color) is a light ray for which the human retina has low resolution and insufficient perception of brightness differences, it is perceived as a harmonious light ray if the same area as the G and R colors is ensured.

[0031] The figure shows that the G and R colors have similar spectral characteristics, and that the light gradually attenuates from the darkest to the brightest areas.

[0032] What can be confirmed from this is that the B, G, and R colors illuminate the subject in roughly equal amounts, making the darkest areas darker and the brightest areas brighter, thus expanding the visible gradation and enabling accurate visualization of objects.

[0033] Furthermore, by increasing the output of the high-brightness white LED2, the light intensity of the green and red colors can also be increased. In addition, although the above example was explained using a single high-brightness white LED2, it is not limited to this, and by enlarging the enclosure and arranging multiple high-brightness white LED2s, it can be made highly versatile as a general lighting device.

[0034] If this pure white light-emitting device is used as a photographic light, the skin's color and texture will be accurately illuminated (unlike current lights with an abnormally strong red tint, which appear bluish-white), eliminating the need for excessive makeup (coloring to match skin tone) on set. Furthermore, shadowless illumination used in medical institutions will be significantly and rationally improved (accurate coloring of affected areas and expanded illumination density range). Damage to the eyes of those involved in surgery from diffuse reflection of metal objects used in surgery will be reduced.

Claims

1. An LED light-emitting section consisting of high-brightness white LEDs, A first reflecting part that reflects the light emitted from the LED of the LED light-emitting part in one direction, A lens disposed on the opening side of the front surface of the first reflector, which collects or scatters light, A filter that absorbs light of a predetermined color from the light that has passed through the lens, A second reflecting section that reflects the light reflected by the filter back to the first reflecting section, A light guide is provided on the opening side and emits light reflected by the first reflector and the second reflector to the outside, A predetermined space is provided between the lens and the light guide, An LED lighting device characterized by having the following features.

2. The LED lighting device according to claim 1, characterized in that the space mixes light that is repeatedly reflected between the first reflecting part, the second reflecting part, and the light guide.

3. The LED lighting device according to claim 1, characterized in that the filter is a color filter that absorbs R-colored light.

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