Illumination device for illuminating a color display - Patent Application 20070122967

Abstract

To provide a lighting device for lighting a color display that easily reduces eye fatigue and improves visibility by adjusting the color of light generated from a color display of information terminal equipment.SOLUTION: A lighting device for lighting a color display is used for dimming a color display of information terminal equipment and has a light source portion composed of a plurality of LED devices.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an illumination device for illuminating a color display. [Background technology]

[0002] In recent years, information terminal devices that allow people to visually view information displayed on a screen, such as smartphones, tablet-type information terminal devices, car navigation devices, laptop computers, game devices, and vehicle instrument panels, have rapidly become popular and have become widespread in our lives.

[0003] For example, when using a smartphone, people turn off the lights in their room at night and look at the smartphone screen until just before going to sleep, browsing internet sites and using social media network services.

[0004] The human retina contains photoreceptors that detect light. Image-forming vision, commonly referred to as vision, including light-dark, color, shape, and motion perception, is known to be detected by the photoreceptors cones and rods present in the retina. However, in recent years, attention has been focused on non-image-forming vision, which is a type of vision that is not image-forming but is influenced by circadian rhythms such as sleep-wake rhythms. This non-image-forming vision was recognized in 2002 based on the discovery of intrinsically photosensitive retinal ganglion cells (ipRGCs), a new type of photoreceptor distinct from cones and rods, in the mammalian retina. ipRGCs are non-image-forming vision, i.e., photoreceptors that detect light unconsciously.

[0005] The retinal photoreceptors, cones, rods, and ipRGCs, contain photopigments, proteins called opsins, which change color in response to light. Photopigments are substances that change color when exposed to light. This change in color detects light and transmits a signal to the brain. The photopigments contained in cone cells have absorption peaks at 559 nm for red, 531 nm for green, and 419 nm for blue. The photopigments contained in rod cells have absorption peaks at 496 nm. The light perception by these photopigments is transmitted as a signal to the visual cortex in the cerebral cortex.

[0006] On the other hand, ipRGCs contain a special visual pigment called melanopsin, a type of opsin with an absorption peak wavelength of 484 nm, which makes them more sensitive to light. In other words, it is known that when stimulated by specific light, people perceive things more brightly.

[0007] Furthermore, in recent years, research has been conducted into lighting that uses LED devices and that does not cause fatigue in people. For example, Patent Document 1 below discloses a light source that emits light that gives a sense of brightness in dark places, provides high visibility, and does not cause fatigue, and that emits light in which the color purity is included in the range of 2 to 50 in the region surrounded by the line segments WB and WG connecting the coordinate W (0.33, 0.33) indicating achromatic color on the CIE 1931 chromaticity diagram with the coordinate B (0.091, 0.133) at 480 nm on the spectrum locus and the coordinate G (0.373, 0.624) at 560 nm on the spectrum locus, and that the area occupied by continuous spectral wavelengths in the wavelength range of 480 to 540 nm is 15% or more of the spectral wavelength area of ​​the entire light source from 380 to 780 nm.

[0008] In addition, Patent Document 2 below discloses a lighting device that can enhance the visibility of characters on a display without giving the user a sense of discomfort during visual work in an office or the like. Specifically, it is a lighting device provided with a light-emitting part. When the lighting device is installed on the ceiling and the vertical direction directly below the light-emitting part is set as the vertical angle of 0°, the color of the first light emitted in the direction of the vertical angle of 0° among the illumination light irradiated from the lighting device has a correlated color temperature in the range of 4000K or more and 5800K or less, and in the u’v’ color coordinates of the XYZ color system, it is in the range of 0.7125u’ + 0.3284 < v’ < 0.7125u’ + 0.3339. The second light emitted in the range of a predetermined vertical angle or more among the illumination light irradiated from the lighting device discloses a lighting device having a higher correlated color temperature than the first light.

[0009] In addition, Patent Document 3 below discloses a lighting device that can improve the readability of characters on a display. Specifically, it is provided with a light-emitting part that irradiates first illumination light. The light characteristics of the first illumination light are such that the correlated color temperature is in the range of 3800K or more and 6500K or less, the color deviation Duv is in the range of -9 or more and 0 or less, and the amount of stimulation of intrinsically photosensitive retinal ganglion cells (ipRGC) is 0.6 or more in terms of the value normalized by the light irradiated from a D65 light source. A lighting device for a display is disclosed.

[0010] In addition, Patent Document 4 below discloses a lighting device that can enhance the whiteness and improve the visibility. Specifically, it is provided with a light source having a solid-state light-emitting element. The light source has a correlated color temperature in the range of 5400K to 7000K, a color deviation Duv in the range of -6 to 8, and a chroma value of 2.7 or less obtained using the calculation method defined by The CIE 1997 Interim Color Appearance Model (Simple Version). A lighting device having such a spectral emission characteristic is disclosed.

[0011] Furthermore, Patent Document 5 below discloses an illumination device that suppresses glare felt by elderly people and prevents the colors of characters and objects of observation from appearing less saturated to elderly people. Specifically, the illumination device includes a first light source module and a second light source module surrounding the first light source module, the half beam angle of the first light source module is smaller than the half beam angle of the second light source module, and the correlated color temperature of the light emitted by the first light source module is higher than the correlated color temperature of the light emitted by the second light source module. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 2019-125577 [Patent Document 2] Japanese Patent Application Publication No. 2019-096573 [Patent Document 3] Japanese Patent Application Publication No. 2018-088374 [Patent Document 4] Japanese Patent Application Laid-Open No. 2014-075186 [Patent Document 5] Japanese Patent Application Laid-Open No. 2017-157485 Summary of the Invention [Problem to be solved by the invention]

[0013] Color displays on information terminal devices use the three primary colors (RGB) of light - red (R), green (G), and blue (B) - as pixels, and by mixing these colors, all colors in full color are reproduced. Each color reproduced by this full color system contains a sharp peak for each of the RGB colors to stimulate the visual sense of image formation. These sharp peaks are necessary for color reproduction to be recognized by the visual sense of image formation. However, because such color displays stimulate the human eye only with light of specific wavelengths, they tend to cause eye fatigue.

[0014] In order to solve the above-mentioned problems, an object of the present invention is to provide an illumination device for illuminating a color display that can easily reduce eye fatigue and improve visibility by adjusting the color of light emitted from the color display. [Means for solving the problem]

[0015] One aspect of the present invention is a lighting device for illuminating a color display of an information terminal device, which is used to dim the color display and includes a light source unit composed of multiple LED devices. Such a lighting device for illuminating a color display can adjust the spectral distribution characteristics and illuminance of the color display as viewed by a user, for example, by mixing light from the color display with light emitted from the light source unit of the lighting device. As a result, the color display's emitted color can be dimmed to a color appropriate for various purposes, such as making dim light appear brighter by emphasizing light with wavelengths that stimulate non-image-forming vision and are rarely included in the color display's emitted color, or shifting the correlated color temperature to a lower color temperature to reduce unpleasant glare and improve eye fatigue and visibility. Such a lighting device preferably further includes a lighting fixture for projecting light from the light source unit toward the color display. Examples of information terminal devices include smartphones, tablet-type information terminal devices, car navigation devices, notebook computers, and instrument panels.

[0016] Furthermore, the light emitted from the light source preferably exhibits an emission spectrum with a first peak indicating maximum emission intensity in the wavelength range of 420 to 480 nm. When the relative emission intensity of the first peak is taken as 1.0, the relative emission intensity is in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm and in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm. When a person views a full-color color display in a dark environment, an illumination device exhibiting such an emission spectrum increases the amount of light in the wavelength range of 490 to 520 nm, which stimulates non-image-forming vision and is hardly included in the color display's emitted color. This makes the color display screen appear brighter even in dim light, making it easier to view even under low-illuminance light sources. Furthermore, increasing the amount of light in the wavelength range of 560 to 630 nm can shift the correlated color temperature of the color display's emission to a lower color temperature, thereby reducing unpleasant glare. This reduces eye fatigue and improves visibility for people viewing the color display.

[0017] The plurality of LED devices include at least one first LED device and at least one second LED device, and the first LED device exhibits maximum light emission intensity in a wavelength range of 560 to 660 nm. Peak (A) (hereinafter referred to as 2nd P (also called "ku") Has, Peak (A) When the relative emission intensity is set to 1.0, the maximum relative emission intensity at wavelengths of 420 to 480 nm is 0.4 to 0. In the range of 8 The range is 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm. The relative emission intensity is within the range The second LED device exhibits a maximum light emission intensity in the wavelength range of 420 to 480 nm. Peak (B) (hereinafter referred to as 3rd P (also called "ku") Yes , Peak (B) When the relative emission intensity is set to 1.0, the emission spectrum has a relative emission intensity in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm, and in the range of 0.3 or more over the entire wavelength range of 520 to 580 nm. vinegar.In this way, by mixing the light from the color display with the light from the combination of the first and second LED devices to illuminate the color display, it becomes easier to obtain a lighting device that can reduce eye fatigue and improve visibility for people viewing the color display.

[0018] The first LED device preferably includes a first blue LED element, a first phosphor that is excited by the light emitted from the first blue LED element to emit fluorescence and has a fluorescence peak wavelength in the wavelength range of 490 to 530 nm with a half-width of 80 to 120 nm, a second phosphor that has a fluorescence peak wavelength in the wavelength range of 510 to 580 nm with a half-width of 100 to 130 nm, and a third phosphor that has a fluorescence peak wavelength in the wavelength range of 580 to 680 nm with a half-width of 60 to 100 nm.

[0019] The second LED device preferably includes a second blue LED element, a second phosphor that is excited by the light emitted from the second blue LED element to emit fluorescence and has a fluorescence peak wavelength in the wavelength range of 510 to 580 nm with a half-width of 100 to 130 nm, and a fourth phosphor that has a fluorescence peak wavelength in the wavelength range of 430 to 490 nm with a half-width of 50 to 80 nm. [Effects of the Invention]

[0020] According to the present invention, an illumination device for illuminating a color display can be obtained that is likely to reduce eye fatigue and improve visibility by adjusting the color of light emitted from the color display. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram showing a state in which an illumination device 10 of this embodiment is attached to a smartphone 100. As shown in FIG. [Figure 2] FIG. 2 is a schematic plan view of a light source module 3 that is composed of a plurality of LED devices 1a and 1b that contain phosphors. [Figure 3]FIG. 3 is an explanatory diagram illustrating a state in which the lighting device 10 projects light onto the color display 101 of the smartphone 100. As shown in FIG. [Figure 4] FIG. 4 is an explanatory diagram illustrating how the position of the light source 5 of the lighting device 10 is changed to change the illumination area. [Figure 5] FIG. 5 is an explanatory diagram of an illumination device 20 according to another embodiment. [Figure 6] FIG. 6 is an explanatory diagram of an illumination device 30 according to another embodiment. [Figure 7] FIG. 7 is an explanatory diagram of an illumination device 40 according to another embodiment. [Figure 8] FIG. 8 is an explanatory diagram of an illumination device 50 according to another embodiment. [Figure 9] FIG. 9 is a schematic front view showing a state in which an illumination device 60 according to another embodiment is attached to a color display 110 of a car navigation device. [Figure 10] FIG. 10 is a schematic diagram illustrating the layer structure when the illumination device 60 is disposed on a color display 110 of a car navigation device. [Figure 11] FIG. 11 shows the emission spectra of each lighting device obtained in the examples relating to the lighting device of this embodiment. [Figure 12] FIG. 12 is a schematic plan view of an LED device 200 for constituting the light source section of the lighting device of this embodiment. [Figure 13] FIG. 13 is a schematic cross-sectional view of the LED device 200 of FIG. 12 taken along the line BB'. [Figure 14] FIG. 14 shows the spectral distribution of each screen display when different types of screen displays (display screens A to D) are displayed on the color display of a smartphone. [Figure 15] FIG. 15 is an explanatory diagram illustrating a method for measuring the illuminance and color coordinates of a color display. DETAILED DESCRIPTION OF THE INVENTION

[0022] The lighting device of this embodiment is used to dim the color display of an information terminal device such as a smartphone, a tablet-type information terminal device, a car navigation device, a notebook computer, or an instrument panel, and is a lighting device for illuminating a color display having a light source unit composed of multiple LED devices.

[0023] As an example of the illumination device according to the present invention, several embodiments of an illumination device for illuminating a color display of an information terminal device will be described in detail as a first embodiment.

[0024] 1A and 1B are explanatory diagrams showing a state in which an illumination device 10 according to this embodiment is attached to a smartphone 100, which is an information terminal device, with (a) being a front view and (b) being a right side view. The smartphone 100 is equipped with a color display 101 that displays various information in full color.

[0025] In FIG. 1 , 10 denotes an illumination device including a light source unit 5 and an illumination fixing unit 2 for projecting light emitted from the light source unit 5 toward a color display 101. As shown in FIG. 2 , the light source unit 5 includes a light source module 3 having two types of LED devices 1a and 1b with different emission spectra, sealed in a molded body made of a transparent material such as silicone resin. The illumination device 10 also includes an illumination fixing unit 2 for clamping the upper part of the housing of the smartphone 100 and fixing the light source unit 5 so that light emitted from the light source unit 5 is projected toward the color display 101. Note that the light source module 3 of this embodiment is a structure having two types of LED devices 1a and 1b arranged therein. However, instead of such a light source module, a light source module having a plurality of LED devices of only one type arranged therein or a light source module having a plurality of LED devices of three or more types arranged therein may be used.

[0026] The light source module 3 shown in FIG. 2 is an LED device assembly in which two types of LED devices 1a and 1b are mounted, three at a time, alternately on a surface-mount circuit board 3a for mounting the LED devices. The surface-mount circuit board 3a is provided with a power supply circuit (not shown) for supplying power, controlled to a predetermined current, to the LED devices 1a and 1b. The power supply circuit adjusts the current supplied to each LED device 1a and 1b to control their brightness. The current supplied to each LED device is not particularly limited, but is preferably 1 to 200 mA, 2 to 150 mA, or even 3 to 100 mA. The current can be appropriately adjusted by controlling the current value or resistance depending on the required brightness of the illumination light. Alternatively, the brightness of the illumination light may be controlled by pulse-controlling the illumination of each LED device.

[0027] The LED devices 1a and 1b then light up when a predetermined amount of power is supplied from the power source 4 through the power supply circuit. The power source 4 is not particularly limited and may be a lithium ion battery housed in the lighting device 10 that is charged by receiving power from a USB terminal, a primary battery, a battery housed in the smartphone 100, or a 100V power source that receives power from a household outlet, and is not particularly limited.

[0028] 3A and 3B are explanatory diagrams illustrating the state when the lighting device 10 projects light onto the color display 101 of the smartphone 100, where (a) is a front view and (b) is a right side view.

[0029] As shown in FIG. 3 , the illumination device 10 of this embodiment is used to project light emitted from two types of LED devices 1a and 1b, which are turned on by power supplied from a light source unit 5 housing a light source module 3, onto a color display 101. According to this illumination device 10, the light emitted from the light source unit 5 can be dimmed according to the purpose, and the light emitted from the color display 101 can be mixed with the light emitted from the light source unit 5, allowing a person to view a screen dimmed to a desired color. Specifically, for example, the light emitted from the color display 101 can be dimmed to prevent glare by shifting the correlated color temperature to a lower color temperature to reduce unpleasant glare, or to reduce eye fatigue, improve visibility, or to a color that does not interfere with sleep or that wakes the user up.

[0030] It is preferable that a lighting device be able to adjust the area of ​​light irradiated onto a color display depending on the size and arrangement of the color display. In lighting device 10 shown in Fig. 1, lighting fixture 2 clamps the upper part of the housing of smartphone 100 and projects light emitted from light source unit 5 toward color display 101. In such lighting device 10, as shown in Fig. 4, it is preferable to use lighting fixture 2 with a sliding structure that changes the position of light source unit 5 with respect to the screen of color display 101, because this allows the area of ​​light irradiated onto color display 101 to be adjusted.

[0031] FIG. 5 is an explanatory diagram of a lighting device 20 according to another embodiment. The lighting device 20 includes a lighting fixture 12, which includes a clamping base 12a that clamps the upper portion of the housing of the smartphone 100 and a lighting support 12b that detachably supports the light source unit 5 on the clamping base 12a using a magnet or the like. This lighting device 20 is preferable because it can be easily carried around by removing the lighting support 12b from the clamping base 12a when not in use. FIG. 6 is an explanatory diagram of a lighting device 30 according to another embodiment. The lighting device 30 also has a structure that allows the lighting fixture 22b, to which the light source unit 5 is joined, to be attached and detached from the lighting fixture base 22a by a slide rail when not in use.

[0032] 7 is a schematic explanatory diagram of an illumination device 40 according to another embodiment. The illumination device 40 has a similar configuration to the illumination device 10, except that the illumination device 40 includes an illumination fixing unit 32 having a flexible portion 32b that is connected to a clamping base 32a and can be deformed by bending, and the light source unit 5 is fixed to the tip of the flexible portion 32b. This structure in which the light source unit 5 is fixed via the flexible portion 32b is preferable because the area on the color display 101 onto which light is irradiated can be freely adjusted by moving the flexible portion 32b.

[0033] 8 is an explanatory diagram of an illumination device 50 according to another embodiment. The illumination device 50 includes an illumination fixing unit 42 having a reflecting member 43 connected to a clamping base 42a. The illumination device 50 also includes a light source module 3 in which two types of LED devices 1a and 1b are arranged, and a light source unit 45 having the reflecting member 43. In the illumination device 50, the light source unit 45 has the reflecting member 43, and light emitted from the two types of LED devices 1a and 1b is reflected and mixed inside the reflecting member 43, thereby distributing the light on the surface of the color display 101 as shown by the arrows.

[0034] The above describes embodiments of the lighting device used to adjust the light color of the color display of the smartphone 100. Note that each of the lighting devices described above can also be applied to a tablet-type information terminal device in the same way, instead of a smartphone.

[0035] 9 is a front view showing the state when the lighting device 60 of this embodiment is attached to a color display 110 of a car navigation device, which reduces eye fatigue and improves visibility for a person viewing the color display of the car navigation device. FIG. 10 is a schematic explanatory diagram for explaining the layer structure when the lighting device 60 is arranged on the color display 110 of the car navigation device.

[0036] The car navigation device is equipped with a color display 110 that displays various information in full color. The color display 110 is surrounded by a housing frame. An illumination device 60 is attached to the frame by adhesive or with screws, nuts, suction cups, etc.

[0037] 9 and 10, reference numeral 60 denotes an illumination device including a light source unit 55 and an illumination fixing unit 52 which is a light guide plate for projecting light emitted from the light source unit 55 toward a color display 110. The light source unit 55 is integrated with a light source module 3 in which a plurality of LED devices are arranged so that light is incident from one side of the light guide plate which is made of a molded body of a transparent material such as silicone resin or acrylic resin.

[0038] The light source module is configured, for example, by mounting multiple LED devices on a surface-mounted circuit board. A power supply circuit (not shown) is formed on the surface-mounted circuit board to supply power to each LED device. The LED devices receive power from a power source via the power supply circuit, causing them to light up and emit light. The power source is not particularly limited, and may be a lithium-ion battery or a primary battery housed in the lighting device 60 that is charged by receiving power from a USB port, or may be powered from a cigarette lighter socket with a basic voltage of 12V or 24V housed in an automobile.

[0039] The above describes embodiments of lighting devices used to adjust the light color of the color display 110 of a car navigation device. Note that each of the lighting devices described above can also be applied to color displays of notebook computers and instrument panels, instead of the color display 110 of a car navigation device.

[0040] The light emission of the lighting device of this embodiment is not particularly limited, but it is particularly preferable that the light emission from the light source unit has a first peak indicating the maximum light emission intensity in the wavelength range of 420 to 480 nm, and exhibits an emission spectrum having a relative light emission intensity in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm and in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, where the relative light emission intensity of the first peak is taken as 1.0.

[0041] Fig. 11 shows the spectrum of light emitted by the lighting device of this embodiment, obtained in an example described later. In Fig. 11, the spectrum satisfying the above-mentioned preferable conditions is shown as an example for lighting device D1.

[0042] In the spectrum of lighting device D1, 11 is a first peak showing the maximum emission intensity in the wavelength range of 420 to 480 nm, with a relative emission intensity of 1.0. 12a is a point showing the minimum emission intensity in the wavelength range of 490 to 520 nm, 12b is a point showing the maximum emission intensity in the wavelength range of 490 to 520 nm, 13a is a point showing the minimum emission intensity in the wavelength range of 560 to 630 nm, and 13b is a point showing the maximum emission intensity in the wavelength range of 560 to 630 nm.

[0043] As shown in the example of lighting device D1 in Figure 11, illuminating a full-color display with light having a relative emission intensity of 0.2 to 0.7, preferably 0.3 to 0.6, and particularly 0.4 to 0.6 over the entire wavelength range of 490 to 520 nm, assuming a relative emission intensity of 1.0 at the first peak wavelength, is preferable because it makes people perceive dim light as bright and makes the color display screen easier to view even under low-illuminance light sources. Furthermore, illuminating a color display with light having a relative emission intensity of 0.5 to 0.9, preferably 0.6 to 0.85, and particularly 0.7 to 0.85 over the entire wavelength range of 560 to 630 nm, assuming a relative emission intensity of 1.0 at the first peak wavelength, is preferable because it shifts the correlated color temperature of the color display's emission to a lower color temperature, thereby reducing unpleasant glare. This reduces eye fatigue and improves visibility for people viewing the color display. Furthermore, an illumination device exhibiting such an emission spectrum can significantly improve the visibility of a color display, particularly in a dark environment.

[0044] In addition, at CIE 1931 color temperatures, the average display screen displayed by a typical full-color display has a correlated color temperature of over 7000 K, and emits light with high levels of glare that cause unpleasant brightness. By using the lighting device of this embodiment to illuminate a color display with light having a spectrum with a relative emission intensity in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm as described above, the color temperature of the color display can be lowered to, for example, less than 7000 K, thereby suppressing unpleasant brightness, known as glare.

[0045] The lighting device of this embodiment includes a light source unit that is an LED device assembly formed by mounting at least two LED devices on a surface-mount circuit board, as described above. The at least two LED devices included in such a light source unit may be a combination of a plurality of LED devices of only one type that exhibit a similar emission spectrum, or a combination of a plurality of LED devices of different types that exhibit different emission spectra, and are appropriately selected depending on the illuminance and irradiation area required for the intended use. The number of at least two LED devices mounted in the lighting device is preferably, for example, in the range of 3 to 30, and more preferably 5 to 20.

[0046] Each of the at least two LED devices preferably includes a phosphor-containing LED device that combines a blue LED device containing a blue LED element with a phosphor as described below, because this facilitates the manufacture of a lighting device having the above-described characteristics. Next, a representative example of a phosphor-containing LED device that can be mounted in such a lighting device will be described with reference to the drawings.

[0047] Fig. 12 is a schematic plan view of an LED device 200 for constituting the light source section of the lighting device of this embodiment. Fig. 13 is a schematic cross-sectional view of the LED device 200 of Fig. 12 taken along the line BB'. Referring to Figs. 12 and 13, the LED device 200 of this embodiment is manufactured such that an LED device body 205 including a blue LED element 201 is covered with a phosphor-containing cap 209, which is a phosphor layer containing phosphor 203 and a light diffusing agent that is blended as needed.

[0048] As shown in FIG. 13, LED device body 205 is a blue LED device including blue LED element 201 that exhibits maximum light emission intensity in the wavelength range of 420 to 480 nm, package member 202 having recess 202a for accommodating blue LED element 201, and transparent resin sealing material 204 for sealing blue LED element 201 accommodated in recess 202a.

[0049] The blue LED element 201 emits light having an emission peak in the blue region of wavelength 420 to 480 nm. Since the LED device main body 205 includes the blue LED element 201, a first peak showing maximum emission intensity is formed in the wavelength range of 420 to 480 nm. The blue LED element provides high phosphor luminous efficiency and is also excellent in long-term reliability.

[0050] The blue LED element may be a gallium nitride (GaN) blue LED element. The transparent resin encapsulant seals and seals the blue LED element housed in the recess. Examples of transparent resins that form the transparent resin encapsulant include silicone resin, epoxy resin, and acrylic resin. The LED device body 205 of this embodiment is a type known as a surface-mounted device (SMD), but other types of LED devices, such as a bullet type, package type, or chip-on-board type (COB type), may be used instead of the SMD.

[0051] A reflective film 207 made of silver plating or the like may be formed on the inner wall surface of the recess 202a of the LED device body 205. One electrode of the blue LED element 201 is connected to a lead 202b, and the other electrode of the blue LED element 201 is wire-bonded with a gold wire 206 and connected to a lead 202c, each of which extends to the outside. The lead 202b is an anode, and the lead 202c is a cathode. The lead 202c of the LED device body 205 is connected to the positive side of a power source, and the lead 202b is connected to the negative side of the power source. When power is applied, the blue LED element 201 emits light. In this LED device body 205, the upper surface of the transparent resin sealing material 204 serves as the light-emitting surface. A phosphor-containing cap 209 is attached to cover the light-emitting surface of the LED device body 205.

[0052] The phosphor-containing cap 209 is a molded body formed into a cap shape from a phosphor sheet that contains a phosphor that emits fluorescence when excited by the light emitted from the blue LED element and is mixed with a light-transmitting resin. Specific examples of light-transmitting resins include silicone rubber (silicone elastomer) and silicone resin.

[0053] Examples of phosphors include europium-activated strontium aluminate (SAE) phosphors; LuAG (LAG) phosphors such as lutetium aluminum garnet phosphors and cerium-activated lutetium aluminum garnet phosphors; silicate phosphors such as chlorosilicate phosphors; yttrium aluminum garnet (YAG) phosphors such as cerium-activated yttrium aluminum garnet phosphors; aluminate phosphors; β-SiAlON:Eu (sialon phosphors); nitride phosphors; and CASN phosphors such as (Sr,Ca)CaAlSiN3:Eu and CaAlSiN3:Eu.

[0054] In particular, to obtain a phosphor-containing LED device that exhibits an emission spectrum in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm, it is preferable to blend a LAG-based phosphor that has a fluorescent peak wavelength with a half-width of 80 to 120 nm in the wavelength range of 490 to 530 nm.

[0055] In particular, in order to obtain a phosphor-containing LED device that exhibits an emission spectrum in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, it is preferable to blend a CASN-based phosphor that has a fluorescent peak wavelength with a half-width of 60 to 100 nm in the wavelength range of 580 to 680 nm.

[0056] Furthermore, it is preferable to adjust the emission spectrum by blending a YAG-based phosphor having a fluorescent peak wavelength with a half-width of 100 to 130 nm in the wavelength range of 510 to 580 nm, an SAE-based phosphor having a fluorescent peak wavelength with a half-width of 50 to 80 nm in the wavelength range of 430 to 490 nm, or the like.

[0057] Furthermore, it is preferable to blend a light diffusing material into the phosphor-containing cap to diffuse the light from the blue LED element with a wavelength of 420 to 480 nm, thereby efficiently exciting the phosphor in the phosphor-containing cap. Examples of such light diffusing materials include silica and calcium carbonate.

[0058] Furthermore, a colorant may be blended into the phosphor-containing cap as needed to adjust the emitted color by absorbing light of a specific wavelength. Specific examples of such colorants include organic or inorganic green pigments such as chrome green, chromium oxide, pigment green B, malachite green lake, fanal yellow green G, and phthalocyanine green. Furthermore, to adjust the overall brightness of the light source, white pigments such as titanium oxide, talc, and barium sulfate, and black pigments such as carbon black can be used in combination. These may be mixed with the phosphor or may be blended in a layer that does not contain the phosphor.

[0059] Alternatively, instead of the phosphor-containing cap described above, a flat phosphor sheet containing phosphor may be bonded to the LED device, or a phosphor layer containing phosphor may be provided on the light-emitting surface of the LED device body to produce a phosphor-containing LED device. The phosphor layer may be formed on the surface of the blue LED element, or may be formed as a film by coating or printing inside or on the surface of a transparent resin encapsulant. A film-like phosphor layer formed on the surface of a transparent resin encapsulant is particularly preferred because it allows for fine adjustment of the amount of phosphor and light color modifier blended into the phosphor layer, the spectral wavelength and emission intensity, and facilitates manufacturing of the LED device. Furthermore, instead of forming a phosphor layer, phosphors may be dispersed in the transparent resin encapsulant that encapsulates the blue LED element.

[0060] An illumination device as described above, in which the light emitted from the light source unit has a first peak indicating the maximum light emission intensity in the wavelength range of 420 to 480 nm, and exhibits an emission spectrum with relative light emission intensities in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm and in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, when the relative light emission intensity of the first peak is taken as 1.0, can be manufactured more simply, for example, as follows.

[0061] For example, referring to FIG. 11, the lighting device D2 exhibits a maximum relative luminous intensity of 1.0 in the wavelength range of 560 to 660 nm. Peak (A) (Part 2nd P Q)1 Has 4 , Peak (A) 1 If the relative emission intensity of peak 4 is taken as 1.0, the maximum relative emission intensity of peak 15, which shows the maximum emission intensity in the wavelength range of 420 to 480 nm, is 0.4 to 0.8, or even 0.6 to 0. In the range of 7 The illumination device D3 exhibits an emission spectrum ranging from 0.2 to 0.7, and even from 0.3 to 0.6, over the entire wavelength range of 490 to 520 nm. The illumination device D3 exhibits a maximum relative emission intensity of 1.0 over the wavelength range of 420 to 480 nm. Peak (B) (Part 3rd P Q) Yes , Peak (B) When the relative emission intensity is taken as 1.0, the illumination device D1 exhibits an emission spectrum with a relative emission intensity of 0.2 to 0.7, particularly 0.25 to 0.5, over the entire wavelength range of 490 to 520 nm, and 0.3 or greater over the entire wavelength range of 520 to 580 nm. In FIG. 11, illumination device D1 exhibits an emission spectrum with a first peak 11, which indicates the maximum emission intensity over the wavelength range of 420 to 480 nm, and a relative emission intensity of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm, and 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, when the relative emission intensity of first peak 11 is taken as 1.0. This illumination device D1 exhibits an emission spectrum intermediate between illumination devices D2 and D3. Therefore, the illumination device D1 can be easily adjusted by combining and adjusting the LED devices that form illumination device D2 or D3.

[0062] The lighting device of this embodiment has been described in detail above. The lighting device of this embodiment is not limited to the configuration described above, and may include other elements or be modified. Specifically, for example, the LED device may be a blue LED device including a blue LED element that does not contain a phosphor, a color filter that adjusts the spectral wavelength of the LED device, a light diffusing material for extracting light without color unevenness, or a light guide member or lens member for controlling the light distribution, as needed. [Example]

[0063] The present invention will be described in more detail below with reference to examples, although the scope of the present invention is not limited to the examples.

[0064] [Phosphor] The phosphors used in this example are summarized in Table 1 below.

[0065] [Table 1]

[0066] [LED device manufacturing] Silicone rubber compositions containing phosphors F1 to F4 shown in Table 1 and light diffusing material D (calcium carbonate) were prepared by uniformly dispersing them in silicone rubber at the blending ratios shown in Table 2 below, and each composition was hot-press molded to produce phosphor-containing caps C1 and C2 with a thickness of 0.3 mm.

[0067] [Table 2]

[0068] Then, phosphor-containing caps C1 and C2 were attached to the light-emitting surface of the blue LED device using a silicone adhesive to produce phosphor-containing LED devices L1 (first LED device) and L2 (second LED device). The blue LED device used was NSSB064 (emission peak: 467 nm) manufactured by Nichia Corporation.

[0069] [Lighting equipment manufacturing] As shown in Figure 2, a strip-shaped surface mount circuit board measuring 7 mm in height and 10 mm in width was equipped with lands No. 1 to No. 6 arranged in order from the left edge of the paper, capable of mounting six LED devices L1 (1a) or LED devices L2 (1b) at 15 mm intervals. A total of six phosphor-containing LED devices were mounted on the board using either the phosphor-containing LED device L1 or L2 shown in Table 2 in the combinations shown in Table 3.

[0070] [Table 3]

[0071] Then, the six phosphor-containing LED devices (L1, L2) mounted in each of the lighting devices D1 to D3 were supplied with power at a supply current of 10 mA to light the lighting devices D1 to D3, and the emission spectra were measured using a spectroradiometer (CL-500A manufactured by Konica Minolta, Inc.). The range of relative emission intensity in the wavelength range of 490 to 520 nm and the range of relative emission intensity in the wavelength range of 560 to 630 nm were read. The obtained emission spectra of the lighting devices D1 to D3 are shown in Figure 11.

[0072] We also prepared a smartphone (Xperia 8 manufactured by Sony Corporation) equipped with a Full HD liquid crystal color display of approximately 6.0 inches. The Xperia 8 manufactured by Sony Corporation was used as a representative smartphone among the various smartphones currently on the market in order to demonstrate average spectral distribution and illuminance. Figure 14 shows an example of the spectral distribution of each screen display when different types of screen displays (display screens A to D) are displayed on the liquid crystal color display of the Xperia 8 manufactured by Sony Corporation.

[0073] As shown in Figure 1, one of the lighting devices D1 to D3 was fixed to the top of the smartphone's housing. As shown in Figure 15, the illuminance and color coordinates were measured from a measurement distance of 30 cm at the center of the HD LCD color display using a spectroradiometer (CL-500A manufactured by Konica Minolta, Inc.). The color temperature was also calculated. The measurement distance of 30 cm was adopted as the average distance between the eyes and the screen when viewing a smartphone screen. The six phosphor-containing LED devices (L1, L2) mounted in each of the lighting devices D1 to D3 were supplied with power at supply currents of 10 mA, 20 mA, and 30 mA.

[0074] Then, ten smartphone users were asked to judge the visibility of an HD LCD color display illuminated with one of the lighting devices D1 to D3 in a dark place, based on the following criteria. Each person adjusted the amount of supplied current within the range of 10 to 30 mA. The judgment was then determined by majority vote.

[0075] (Judgment criteria) A: There was no noticeable discomfort with the colors on the LCD color display when the lighting device was off, and the flickering and unpleasant glare caused by the brightness of the screen was suppressed, so the eyes felt less tired. B: There was some discomfort due to the slight color change, but glare was suppressed and my eyes felt less tired. C: Glare was felt and eyes felt tired easily.

[0076] The evaluation results are shown in Table 4 below.

[0077] [Table 4]

[0078] As shown in Table 4, the color of light emitted from the LCD color display illuminated by the lighting devices obtained in all Examples had a lower color temperature than the color of light emitted from the LCD color display not illuminated by the lighting device of the Comparative Example, thereby reducing unpleasant glare. Furthermore, in Examples 1-1, 1-2, 1-3, and 1-4, which used LED lighting device D1, whose light source has a first peak indicating the maximum emission intensity in the wavelength range of 420 to 480 nm and an emission spectrum with a relative emission intensity in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm and a relative emission intensity in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, assuming that the relative emission intensity of the first peak is 1.0, no significant discomfort was felt with respect to the color of the LCD color display when the lighting device was off. Furthermore, eye flickering due to screen brightness and unpleasant glare were suppressed, resulting in less eye fatigue. [Explanation of symbols]

[0079] 1a,1b LED device 2 Lighting fixing part 3 Light Source Module 3a Surface Mount Circuit Board 4 Power supply 5,45,55 Light source section 10,20,30,40,50,60 Lighting equipment 12,22b,32,42,52 Lighting fixing part 60 Lighting Equipment 100 smartphones 101,110 color display 200 LED devices 201 Blue LED element 202 Packaging materials 203 Phosphor 204 Transparent resin encapsulant 205 LED device body 209 Phosphor-containing cap

Claims

1. Used to dim the color displays of information terminal devices, A light source unit is provided which is composed of a plurality of LED devices, the plurality of LED devices include at least one first LED device and at least one second LED device; the first LED device has a peak (A) showing a maximum emission intensity in a wavelength range of 560 to 660 nm, and when the relative emission intensity of the peak (A) is taken as 1.0, the maximum relative emission intensity in a wavelength range of 420 to 480 nm is in a range of 0.4 to 0.8, and the relative emission intensity in the entire wavelength range of 490 to 520 nm is in a range of 0.2 to 0.7; the second LED device has a peak (B) showing the maximum emission intensity in the wavelength range of 420 to 480 nm, and exhibits an emission spectrum having a relative emission intensity in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm, and in the range of 0.3 or more over the entire wavelength range of 520 to 580 nm, where the relative emission intensity of the peak (B) is taken as 1.0; An illumination device for illuminating a color display.

2. 2. The lighting device for illuminating a color display according to claim 1, further comprising a lighting fixture for projecting light emitted from said light source unit toward said color display.

3. 3. The lighting device for illuminating a color display according to claim 1 or 2, wherein the light emitted from the light source unit has a first peak indicating maximum light emission intensity in a wavelength range of 420 to 480 nm, and exhibits an emission spectrum having relative light emission intensities in the range of 0.2 to 0.7 over the entire wavelength range of 490 to 520 nm and in the range of 0.5 to 0.9 over the entire wavelength range of 560 to 630 nm, where the relative light emission intensity of the first peak is taken as 1.

0.

4. 4. The lighting device for illuminating a color display according to claim 1, wherein the first LED device comprises: a first blue LED element; a first phosphor that is excited by light emitted from the first blue LED element to emit fluorescence, the first phosphor having a fluorescence peak wavelength in a wavelength range of 490 to 530 nm and a half-width of 80 to 120 nm; a second phosphor that has a fluorescence peak wavelength in a wavelength range of 510 to 580 nm and a half-width of 100 to 130 nm; and a third phosphor that has a fluorescence peak wavelength in a wavelength range of 580 to 680 nm and a half-width of 60 to 100 nm.

5. 5. The lighting device for illuminating a color display according to claim 1, wherein the second LED device comprises: a second blue LED element; a second phosphor that is excited by light emitted from the second blue LED element to emit fluorescence and has a fluorescence peak wavelength in a wavelength range of 510 to 580 nm with a half-width of 100 to 130 nm; and a fourth phosphor that has a fluorescence peak wavelength in a wavelength range of 430 to 490 nm with a half-width of 50 to 80 nm.

6. The lighting device according to any one of claims 1 to 5, wherein the information terminal device is a smartphone, a tablet information terminal device, a car navigation device, a notebook computer, or an instrument panel.

Images