Lighting equipment

Abstract

To provide a lighting device capable of applying illumination light which is easy on eyes while suppressing illuminance unevenness.SOLUTION: The lighting device which is mounted at the upper end of a display for applying illumination light to a desk surface includes a light source part having a base plate and a plurality of LED elements for emitting illumination light, a body part storing the light source part, and a latch part to be latched to the upper end of the display while supporting the body part, the body part having a rectangular emission opening for emitting the illumination light from the plurality of LED elements, and a cover member in which the illumination light from the plurality of LED elements is transmitted, the cover member having a first region in which the illumination light is transmitted as it is, and a second region in which the illumination light is transmitted while being diffused therefrom. The ratio per unit area of the first region to the second region is gradually higher as separating from the display.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an illumination device that is attached to the upper end of a display of a computer placed on a desk surface and irradiates illumination light toward the desk surface. [Background technology]

[0002] In recent years, with the spread of teleworking, opportunities for online conferences using computers are increasing. In such online conferences, the computer (i.e., the user) is not necessarily under ideal lighting, and depending on the environment in which the computer is installed, there may not be space to install an existing desk lamp, making it difficult to see the conference materials, keyboard, etc. In such a case, when the work environment is dark, a lighting device is used to illuminate the user's hands (i.e., the desk surface) (for example, Non-Patent Document 1).

[0003] Non-Patent Document 1 describes an illumination device that is attached to the top edge of a computer display and is powered by a USB port on the computer. This illumination device has multiple built-in LED elements and is configured to irradiate illumination light from above onto the work area below the display (i.e., the desk surface). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "e-Reading Lamp Monitor Mounted Light | WiT ScreenBar", [online], BenQ Corporation, [Retrieved June 20, 2021], Internet<URL:https: / / www.benq.com / ja-jp / lighting / screenbar-lamp / screenbar.html> Summary of the Invention [Problem to be solved by the invention]

[0005] According to the lighting device of Non-Patent Document 1, even if the working environment is dark, the area around the user's hands is brightly illuminated, so that the user can work comfortably without disturbing those around him / her. In addition, since power is supplied from the computer's USB port, there is no need to prepare a dedicated power supply device such as an AC adapter, making it highly portable and easy to install. However, such conventional lighting devices have a problem in that the difference between bright and dark areas is large (that is, there is uneven illuminance), which can easily cause eye fatigue.

[0006] Fig. 14 is a cross-sectional view showing an example of the configuration of a conventional lighting device. As shown in Fig. 14, a conventional lighting device 10 is composed of a substrate 12, a plurality of LED chips 15 arranged on the substrate 12, a reflection mirror 16 that reflects light from the LED chips 15, and a case 11 that houses them, and the light reflected by the reflection mirror 16 is emitted as illumination light (light ray Lo) toward the user's hand.

[0007] FIG. 15 shows the results of evaluating the light distribution characteristics (illuminance) when a conventional lighting device 10 is hung on the upper end of a display D on a desk surface, assuming that the device is placed at a height of 40 cm from the desk surface, and turned on at maximum illuminance. FIG. 15(a) shows the evaluation result according to the JIS Standard Type A standard (JIS C8112), and FIG. 15(b) shows the evaluation result according to the Illuminating Engineering Society of North America standard. As shown in Fig. 15(a), when the illumination light from the conventional lighting device 10 is set to an irradiation range R1 in a sector-shaped range in front of the lighting device 10 on the desk surface, the illuminance on 1 / 3 of the circumference with a radius of 50 cm in front (on the outer arc) is 120-290 lux, and the illuminance on 1 / 3 of the circumference with a radius of 30 cm in front (on the inner arc) is 620-750 lux, and it was found that the proximal side of the lighting device 10 is much brighter than the distal side, and does not meet the JIS standard type A standard. Also, as shown in Fig. 15(b), when the illumination light from the conventional lighting device 10 is set to an irradiation range R2 in a rectangular range of 41 cm to 10 cm in front of the lighting device 10 and 36 cm on both sides on the desk surface, the proximal side of the lighting device 10 is much brighter than the distal side, and the uniformity (minimum illuminance / maximum illuminance) in the irradiation range R2 is 130 lux / 1190 lux = 10.9%.

[0008] As described above, it was found that the configuration of the conventional lighting device 10 is such that the difference between the bright and dark areas is large (i.e., there is uneven illuminance), and therefore it is unable to satisfy the JIS Type A standard (JIS C8112) and the standard for uniformity set by the Illuminating Engineering Society of North America, and therefore the eyes are easily fatigued. The present invention has been made based on such findings, and an object of the present invention is to provide an illumination device capable of suppressing uneven illuminance and emitting illumination light that is gentle on the eyes. [Means for solving the problem]

[0009] In order to achieve the above object, the lighting device of the present invention is an illumination device that is attached to the upper end of a display of a computer placed on a desk surface and irradiates illumination light toward the desk surface, and is equipped with a light source unit having a substrate extending approximately horizontally along the upper end of the display and a plurality of LED elements arranged on the surface of the substrate and emitting illumination light, a main body unit that houses the light source unit and extends approximately horizontally along the upper end of the display, and a hook unit that supports the main body unit so that it is positioned forward of the surface of the display and hooks onto the upper end of the display, the main body unit facing the desk surface and having a rectangular emission opening through which the illumination light from the plurality of LED elements is emitted, and a cover member that is arranged on the optical axis of the plurality of LED elements and through which the illumination light from the plurality of LED elements is transmitted, the cover member having a first region through which the illumination light transmits as it is and a second region through which the illumination light transmits while being diffused, and the ratio of the first region to the second region per unit area increases with increasing distance from the display.

[0010] With a lighting device configured in this way, the light beam of the illumination light is restricted by the exit aperture, so the illumination light does not directly enter the user's eyes, and is not reflected on the display. In addition, it is possible to uniformly illuminate the illumination range of the desk surface.

[0011] In addition, when the emission opening is placed at a height of 40 cm from the desk surface and multiple LED elements are operated with a power consumption of 4.5 W, it is desirable that the illuminance on 1 / 3 of a circumference with a radius of 50 cm in front of the lighting device on the desk surface be 150 lux or more, and the illuminance on 1 / 3 of a circumference with a radius of 30 cm in front be 300 lux or more.

[0012] It is also preferable that the cover member is made up of a transparent substrate and a matte ink laminated on the rear surface of the substrate, and that the second region is formed by the matte ink.

[0013] Moreover, it is preferable that the plurality of LED elements are composed of a plurality of white LED chips that emit white light and a plurality of warm white LED chips that emit warm white light.

[0014] It is also desirable for the lighting device to be powered by power supplied from a USB port on a computer. Effect of the Invention

[0015] As described above, according to the lighting device of the present invention, a lighting device capable of emitting illumination light with little unevenness in illuminance and which is gentle on the eyes is realized. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a configuration of an illumination device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating the state of illumination light emitted from the illumination device according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is an exploded perspective view showing an internal configuration of a main body of the lighting device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 5 is a plan view illustrating the configuration of a light source unit of the illumination device according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a block diagram illustrating electrical connections of the lighting device according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing a state (posture) when the illumination device according to the first embodiment of the present invention is hung on the upper end of a display. [Figure 8] FIG. 8 is a side view showing rays of illumination light emitted from the lighting device according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view illustrating the light ray angle of the illumination light emitted from the illumination device according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the results of evaluating the light distribution characteristic (illuminance) of the lighting device according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing a configuration of an illumination device according to a second embodiment of the present invention. [Figure 12] FIG. 12 is a diagram illustrating the configuration of a cover of an illumination device according to a second embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing the results of evaluating the light distribution characteristic (illuminance) of the lighting device according to the second embodiment of the present invention. [Figure 14] FIG. 14 is a cross-sectional view showing an example of the configuration of a conventional lighting device. [Figure 15] FIG. 15 is a diagram showing the results of evaluating the light distribution characteristics (illuminance) of a conventional lighting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0018] (First embodiment) Fig. 1 is a diagram showing the configuration of a lighting device 1 according to a first embodiment of the present invention, Fig. 1(a) is a perspective view of the lighting device 1 when viewed obliquely from the front, Fig. 1(b) is a perspective view of the lighting device 1 when viewed obliquely from the rear, and Fig. 1(c) is a bottom view of the lighting device 1. Fig. 2 is a schematic diagram illustrating the state of illumination light emitted from the lighting device 1. As shown in FIG. 2, the lighting device 1 of this embodiment is a device that is attached to the upper end of a display D of a computer placed on a desk surface and emits lighting light L1 (first lighting light) that illuminates the hands (desk surface) of a user U and lighting light L2 (second lighting light) that illuminates the face of the user U (FIG. 2(a)). In addition, lighting light L3 (third lighting light) that functions as decorative light (illumination) is emitted from a diffusion plate 103 disposed at both ends in the X-axis direction of the lighting device 1 (FIG. 2(b)). In this specification, as shown in the coordinates of FIG. 1 and FIG. 2, the arrangement direction of a white LED chip 115 and a warm white LED chip 116 described later is defined as the X-axis direction, the vertical direction is the Z-axis direction, and the direction perpendicular to the X-axis direction and the Z-axis direction is defined as the Y-axis direction.

[0019] As shown in FIG. 1, the lighting device 1 of this embodiment includes a main body 100 that emits illumination light L1 to L3, and a hooking portion 200 that supports the main body 100 and hooks it onto the upper end of a display D.

[0020] Fig. 3 is an exploded perspective view showing the internal configuration of the main body portion 100. Also, Fig. 4 is a cross-sectional view taken along line AA in Fig. 1(c). As shown in Figs. 1 to 4, the main body 100 includes a case 101 that extends long in the X-axis direction and has a substantially rhombic cross section. The case 101 includes a cover 102 (cover member) through which the illumination light L1 passes and is emitted on the bottom surface (surface on the negative side in the Z-axis direction), and includes a light source unit 110 (first light source), a face LED board 120 (second light source), and an MPU (Micro Processor Unit) board 130 (controller) inside. The bottom surface (surface on the negative side in the Z-axis direction) of the case 101 faces the desk top surface and has a rectangular emission opening 101a through which the illumination light L1 from the multiple LED elements is emitted. The case 101 also includes a diffusion plate 103 and a side cover 104 that covers the outside of the diffusion plate 103 at both ends in the X-axis direction, a light guide plate 105 on the front surface, and a sensor cover 106 on the top surface. The lighting device 1 of this embodiment is electrically connected to a computer (not shown) via a USB cable C, and receives a maximum of 4.5 W of power from a USB port (for example, USB 3.1) of the computer (FIG. 4).

[0021] Fig. 5 is a plan view illustrating the configuration of the light source unit 110. Fig. 6 is a block diagram illustrating the electrical connections of the lighting device 1 of this embodiment. As shown in FIG. 5, the light source unit 110 includes a rectangular plate-shaped substrate 112 extending in the X-axis direction, a plurality (e.g., 40) of white LED chips 115 (first LED elements), a plurality (e.g., 40) of warm white LED chips 116 (first LED elements), two color LED chips 117 (third light source, third LED elements), and an MPU 118. White LED chip 115 is composed of, for example, a blue LED chip (not shown) that emits blue light, and a phosphor (not shown) that receives the energy of the blue light from the blue LED chip and emits yellow light, and the blue light and the yellow light are mixed together to emit white light (for example, approximately 4200K) from white LED chip 115. In addition, the warm white LED chip 116 is composed of, for example, a blue LED chip (not shown) that emits blue light, and a phosphor (not shown) that receives the energy of the blue light from the blue LED chip and emits yellow light, and the blue light and the yellow light are mixed together to emit warm white light (for example, approximately 3000K) from the warm white LED chip 116.

[0022] The plurality of white LED chips 115 and the plurality of warm white LED chips 116 are arranged on the surface of the substrate 112 at predetermined intervals in the X-axis direction with their optical axes aligned in a direction perpendicular to the substrate 112, and are electrically connected to the substrate 112. The two color LED chips 117 are arranged at both ends (in the X-axis direction) of the substrate 112 with their optical axes facing outward from the substrate 112 (i.e., facing the + and - sides in the X-axis direction), and are electrically connected to the substrate 112. The substrate 112 is electrically connected by a wiring cable (not shown) extending from the MPU substrate 130, and a drive current is supplied from the MPU substrate 130 to each of the white LED chips 115, each warm white LED chip 116, and each color LED chip 117. When a drive current is supplied to each white LED chip 115, each white LED chip 115 emits white light with an amount of light corresponding to the drive current. Also, when a drive current is supplied to each warm white LED chip 116, each warm white LED chip 116 emits warm white light with an amount of light corresponding to the drive current. As described above, in this embodiment, since the plurality of white LED chips 115 and the plurality of warm white LED chips 116 are arranged alternately, the white light from the white LED chip 115 and the warm white light from the warm white LED chip 116 overlap (i.e., are mixed) in the optical path and are emitted. Then, the white light emitted from each white LED chip 115 and the warm white light emitted from each warm white LED chip 116 are emitted through the cover 102 and the emission opening 101a arranged in the optical path, and illuminate the hand of the user U. In this embodiment, the drive current of the white LED chip 115 and the drive current of the warm white LED chip 116 are each adjustable by the control of the MPU 131, thereby making it possible to adjust the illumination color (whiteness) of the illumination light L1 (a mix of white light and warm white light).

[0023] When a drive current is supplied to the two color LED chips 117, each color LED chip 117 emits color light (red, green, blue, and a mixture of these) with an amount of light corresponding to the drive current as illumination light L3. As described above, in this embodiment, the color LED chips 117 are arranged at both left and right ends (X-axis direction) of the substrate 112 with their optical axes facing outward from the substrate 112 (i.e., toward the + and - sides in the X-axis direction), so that the color light emitted from each color LED chip 117 is diffused by the diffusion plate 103 arranged in the optical path and emitted from an end face of the diffusion plate 103. In this embodiment, the color light emitted from the diffusion plate 103 functions as so-called decorative light (illumination). The drive current of each color LED chip 117 is configured to be adjustable by control of MPU 118 under instructions from MPU 131, so that the color of the color light (i.e., the emitted color of color LED chip 117) changes at a predetermined timing, for example, in the order of "green → yellow → red → pink → purple → blue → light blue → green."

[0024] The face LED board 120 includes a rectangular board 122 extending in the X-axis direction and a plurality (e.g., three) of white LED elements 125 (second LED elements) (FIG. 3). The plurality of white LED elements 125 are arranged in a line on the surface of the board 122 at a predetermined interval in the X-axis direction and are electrically connected to the board 122. The board 122 is also electrically connected by a wiring cable (not shown) extending from the MPU board 130, and each white LED element 125 is supplied with a driving current from the MPU board 130. When a driving current is supplied to each white LED element 125, each white LED element 125 emits white light of an amount of light according to the driving current as illumination light L2. The white light emitted from the white LED element 125 is guided by a light guide plate 105 arranged in the optical path of the white LED element 125 and emitted to illuminate the face of the user U. In this manner, in this embodiment, the white LED elements 125 on the face LED board 120 are turned on to illuminate the face of the user U. In this embodiment, the white LED elements 125 are driven by PWM (Pulse Width Modulation) at a reference frequency of 20 kHz under the control of the MPU 131, thereby adjusting the amount of light.

[0025] The MPU board 130 is electrically connected to the light source unit 110 and the face LED board 120, and is an electronic circuit that controls the light emission of the white LED chip 115, the warm white LED chip 116, the color LED chip 117 of the light source unit 110, and the white LED element 125 of the face LED board 120 in response to input (operation) from the user U. As shown in FIG. 6, the MPU board 130 of this embodiment has an MPU 131 (control unit), a first sensor 132 to a fourth sensor 135 (operation unit), LED drivers 136 and 137, and a USB connector 139.

[0026] The MPU 131 is composed of an arithmetic unit (not shown) that executes logical operations, a RAM (not shown) in which data etc. are temporarily stored, a ROM (not shown) in which a control program is stored, etc., and has the function of controlling the entire lighting device 1. The MPU 131 is electrically connected to the first sensor 132 to the fourth sensor 135 (operation unit) and the LED drivers 136 and 137, and when power is input to the lighting device 1, it reads out the control program stored in the ROM (not shown) and controls each of these units.

[0027] The first sensor 132 to the fourth sensor 135 are user interfaces (switches) that receive input from the user U and output control signals to the MPU 131. The first sensor 132 in this embodiment is a so-called touchless sensor composed of a photointerrupter or the like, and the second sensor 133 to the fourth sensor 135 are touch sensors and are disposed directly under the sensor cover 106. Therefore, when the user U places his / her finger over or touches a position on the sensor cover 106 corresponding to each of the first sensor 132 to the fourth sensor 135, the MPU 131 recognizes the input from the first sensor 132 to the fourth sensor 135 and executes a process assigned to each of the first sensor 132 to the fourth sensor 135.

[0028] In this embodiment, the first sensor 132 is a switch that controls the on / off of the white LED chip 115 and the warm white LED chip 116 of the light source unit 110, and the white LED chip 115 and the warm white LED chip 116 are turned on / off by holding a finger over a position on the sensor cover 106 corresponding to the first sensor 132. In addition, the second sensor 133 is a switch that controls the brightness (illuminance) of the illumination light L1 emitted from the light source unit 110, and by touching a position on the sensor cover 106 corresponding to the second sensor 133, the total amount of light (light emission intensity) of the white LED chip 115 and the warm white LED chip 116 changes in stages. In addition, the third sensor 134 is a switch that controls the color (whiteness) of the illumination light L1 emitted from the light source unit 110. By touching a position on the sensor cover 106 corresponding to the third sensor 134, the balance (ratio) of the light amount of the white LED chip 115 and the light amount (light emission intensity) of the incandescent color LED chip 116 changes gradually, thereby changing the illumination color (whiteness) of the illumination light L1. Further, the fourth sensor 135 is a switch that controls the brightness of the illumination light L2 emitted from the face LED board 120, the brightness of the illumination light L1 emitted from the light source unit 110, and the on / off of the color LED chip 117. By touching a position on the sensor cover 106 corresponding to the fourth sensor 135, the light amount (light emission intensity) of the white LED element 125 on the face LED board 120 changes stepwise. If the white LED chip 115 and the warm white LED chip 116 are on when the white LED element 125 is on, the power consumption increases and may exceed the power supply capacity (4.5 W) of the USB. Therefore, in this embodiment, when the white LED element 125 is on, the light amount (light emission intensity) of the white LED chip 115 and the warm white LED chip 116 is controlled to be reduced (the drive current is reduced). In addition, in this embodiment, the color LED chip 117 can be turned on / off by continuously touching (i.e., pressing and holding) a position on the sensor cover 106 corresponding to the fourth sensor 135 for a predetermined period of time.

[0029] The LED drivers 136 and 137 are electronic circuits that supply current to the white LED chip 115 and the warm white LED chip 116, respectively, and supply a predetermined current to the white LED chip 115 and the warm white LED chip 116 under the control of the MPU 131.

[0030] The USB connector 139 is a connector that is connected to a USB cable C. By connecting the USB connector 139 to a USB port of a computer, a maximum of 4.5 W of power is supplied to the MPU board 130, the light source unit 110, and the face LED board 120.

[0031] Next, returning to Figs. 1, 2 and 4, the configuration of the hook portion 200 of the lighting device 1 of this embodiment will be described. As shown in Figures 1, 2 and 4, the hanging portion 200 is a member that supports the main body portion 100 so that it is positioned forward of the surface of the display D when the lighting device 1 is attached to the display D, and is hung on the upper end portion of the display D, and has a weight portion 210 having a balancing weight therein, and an arm portion 230 that connects between the weight portion 210 and the main body portion 100.

[0032] The weight portion 210 is a member that is disposed so as to come into contact with the rear surface of the display D when the illumination device 1 is hung on the upper end portion of the display D. The arm portion 230 is a plate-shaped member that engages with the upper end of the display D when the lighting device 1 is hung on the upper end of the display D, and a tongue portion 232 that protrudes downward is formed on the lower surface of the arm portion 230 on the main body portion 100 side so as to abut against the surface of the display D. Moreover, the weight portion 210 and the arm portion 230 are rotatably connected via a rotation shaft 215 (first rotation shaft) extending in the X-axis direction, and a torsion spring (not shown) that rotates (biases) the weight portion 210 relative to the arm portion 230 is provided around the rotation shaft 215. Therefore, when the lighting device 1 is hooked onto the upper end portion of the display D, the lower end portion of the weight portion 210 presses the back surface of the display D, and the display D is sandwiched between the weight portion 210 and the tongue portion 232. FIG. 7 shows the state (posture) of the lighting device 1 when it is hung on the upper end of the display D, where FIG. 7(a) shows how it is hung on a thick display D1, FIG. 7(b) shows how it is hung on a display D2 of average thickness, and FIG. 7(c) shows how it is hung on a thin display D3. As described above, the tongue portion 232 of the arm portion 230 engages with the upper end of the display D and the weight portion 210 rotates relative to the arm portion 230, so that the mounting posture of the weight portion 210 differs depending on the thickness of the display D. However, since the display D is held between the weight portion 210 and the tongue portion 232, the display D is always held in a stable posture.

[0033] In this embodiment, the arm unit 230 and the main body unit 100 are rotatably connected via a rotation shaft 235 (second rotation shaft) extending in the X-axis direction. Therefore, after attaching the lighting device 1 to the display D, the main body 100 can be rotated around the rotation axis 235 to adjust the direction of the illumination light L1 from the lighting device 1 toward the hand of the user U and the direction of the illumination light L2 from the lighting device 1 toward the face of the user U.

[0034] In this manner, the illumination device 1 of the present embodiment is configured to be stably hung on the upper end of the display D. As described above, the lighting device 1 of the present embodiment is configured to be capable of illuminating not only the area around the user U's hands but also the user U's face. Therefore, even during an online conference in a dark environment, the conference materials and keyboard at hand can be easily seen, and the image quality during the online conference is also good.

[0035] Fig. 8 is a side view showing the light beams of the illumination light L1 emitted from the illumination device 1 when the illumination device 1 is hung on the upper end of the display D. Fig. 9 is a cross-sectional view illustrating the light beam angles of the illumination light L1 emitted from the illumination device 1.

[0036] 8, the lighting device 1 of this embodiment is assumed to be placed at a height of 40 cm from the desk surface when the lighting device 1 is hung on the upper end of the display D on the desk surface with the emission opening 101a of the lighting device 1 facing directly downward in the vertical direction (Z-axis direction - side), and at this time, the optical axes Ax of the multiple white LED chips 115 and the multiple warm white LED chips 116 are configured to face the desk surface 30 cm forward from the surface of the display D, and the light ray Lu emitted at the maximum angle toward the user U side is not incident on the eyes of the user U located 50 cm forward from the surface of the display D. Also, the light ray Lm emitted at the maximum angle toward the display D side is configured not to be incident on the surface of the display D.

[0037] 9, when the light output opening 101a of the lighting device 1 is directed vertically downward, the optical axes Ax of the white LED chips 115 and the warm white LED chips 116 pass through the light output opening 101a and are inclined at a negative angle (clockwise angle) α of 32° to 38° with respect to the vertical direction. The light output opening 101a of the lighting device 1 of this embodiment regulates the angle of the light beam passing through the light output opening 101a to a maximum angle β of 34.65° to 40.65° in the negative angle direction (clockwise angle direction) and a maximum angle γ of 35.10° to 41.10° in the positive angle direction (counterclockwise angle direction) with respect to the optical axes Ax of the white LED chips 115 and the warm white LED chips 116.

[0038] In this manner, in this embodiment, the angle of the light beam emitted from the lighting device 1 is regulated by the exit opening 101a, so that the illumination light L1 does not enter the eyes of the user U and is not reflected on the display D. The angle α is preferably 33° to 37°, and more preferably 34° to 36°. The maximum angle β is preferably 35.65° to 39.65°, and more preferably 36.65° to 38.65°. The maximum angle γ is preferably 36.10° to 40.10°, and more preferably 37.10° to 39.10°.

[0039] (Illuminance evaluation of lighting device 1) FIG. 10 shows the results of evaluating the light distribution characteristics (illuminance) when the lighting device 1 is arranged as shown in FIG. 8 and the multiple white LED chips 115 and the multiple warm white LED chips 116 are turned on at maximum illuminance (i.e., the maximum power supply (4.5 W) of the USB port of a computer). FIG. 10(a) shows the evaluation result according to the JIS standard A type standard (JIS C8112), and FIG. 10(b) shows the evaluation result according to the Illuminating Engineering Society of North America standard. As shown in Figure 10(a), when the illumination range R1 is a sector-shaped area in front of the lighting device 1 on the desk surface, the illuminance of the illumination light L1 from the lighting device 1 is 155 to 200 lux on 1 / 3 of the circumference with a radius of 50 cm in front (on the outer arc) and 340 to 450 lux on 1 / 3 of the circumference with a radius of 30 cm in front (on the inner arc), which satisfies the JIS Type A standard (150 lux or more on 1 / 3 of the circumference with a radius of 50 cm in front of the lighting device 1, and 300 lux or more on 1 / 3 of the circumference with a radius of 30 cm in front). 10(b), when the illumination light L1 from the lighting device 1 is set to an illumination range R2 on the desk surface, which is a rectangular range of 41 cm to 10 cm in front of the lighting device 1 and 36 cm to the left and right, the uniformity (minimum illuminance / maximum illuminance) in the illumination range R2 is 285 lux / 590 lux = 48.3%, which satisfies the uniformity standard (33% or more) of the Illuminating Engineering Society of North America. Although the uniformity varies somewhat depending on product variations and measurement conditions, it is desirable for the illumination range R2 to be 40% or more, and more desirably 45%. In the case of the configuration of the lighting device 1 of this embodiment, the uniformity in the illumination range R2 is considered to vary in the range of 45 to 55%.

[0040] 14 and 15 (conventional lighting device 10) and FIG. 9 and FIG. 10 (lighting device 1 of this embodiment), in this embodiment, as shown in FIG. 9, when the emission opening 101a of the lighting device 1 is directed vertically downward, the optical axis Ax of the plurality of white LED chips 115 and the plurality of warm white LED chips 116 passes through the emission opening 101a (that is, direct light from the plurality of white LED chips 115 and the plurality of warm white LED chips 116 is emitted from the emission opening 101a) and is angled at a negative angle of 32° to 38° with respect to the vertical direction. By positioning the exit opening 101a so that the angle of the light beam passing through the exit opening 101a is at a maximum angle β: 34.65° to 40.65° in the negative angle direction (clockwise angle direction) and a maximum angle γ: 35.10° to 41.10° in the positive angle direction (counterclockwise angle direction) with respect to the optical axis Ax of the multiple white LED chips 115 and the multiple warm white LED chips 116, the maximum power consumption is 4.5 W, while still satisfying the JIS Type A standard and the Illuminating Engineering Society of North America standard for uniformity. Therefore, the lighting device 1 of this embodiment is configured to receive power from a USB port of a computer (i.e., is highly portable and easy to install), yet provides illumination light L1 with little unevenness in the illumination ranges R1 and R2 on the desk surface that is gentle on the eyes.

[0041] Although the present embodiment has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the technical concept of the present invention.

[0042] Second Embodiment FIG. 11 is a diagram showing the configuration of a lighting device 2 according to a second embodiment of the present invention, in which FIG. 11(a) is a perspective view of the lighting device 2 when viewed diagonally from the front, FIG. 11(b) is a perspective view of the lighting device 2 when viewed diagonally from the rear, and FIG. 11(c) is a bottom view of the lighting device 2. As shown in FIG. 11(c), the lighting device 2 of the present embodiment differs from the lighting device 1 of the first embodiment in that, instead of the cover 102, a cover 150 is provided that transmits while diffusing the illumination light L1.

[0043] Like the lighting device 1 of the first embodiment, the lighting device 2 of this embodiment also includes a white LED chip 115 and an incandescent color LED chip 116, but each of the white LED chips 115 and each of the incandescent color LED chips 116 is configured to include a blue LED chip (not shown) that emits blue light, and a phosphor (not shown) that receives energy of the blue light from the blue LED chip and emits yellow light. In this configuration, the blue light (excitation light) emitted from the blue LED chip is incident on the phosphor with a certain angle distribution with respect to the optical axis direction, so that in the phosphor, the optical path length of the blue light passing through the outer periphery is longer than that of the blue light passing through the center. Therefore, the outer periphery of the phosphor is more likely to produce fluorescence than the center, and the white light and bulb color light (i.e., the illumination light L1) emitted from the phosphor may have a color unevenness called a yellow ring. In this embodiment, in order to solve this problem, the cover 150, through which the white light from the white LED chip 115 and the warm white light from the warm white LED chip 116 pass, is provided with a diffusion function that diffuses a portion of the white light and the warm white light.

[0044] Fig. 12 is a diagram showing the configuration of the cover 150 of this embodiment, Fig. 12(a) is an enlarged plan view, and Fig. 12(b) is a cross-sectional view taken along line BB in Fig. 12(a). As shown in Fig. 12, the cover 150 has a rectangular plate-shaped transparent resin (e.g., polycarbonate) base material 151 and a light diffusion layer 152 laminated on the back surface (the surface facing the light source unit 110) of the base material 151, and the light diffusion layer 152 forms an area S (an area where the light diffusion layer 152 is formed) through which the white light and the light of the bulb color are diffused and transmitted, and an area T (an area where the light diffusion layer 152 is not formed) through which the white light and the light of the bulb color are transmitted as they are. In this embodiment, the light diffusion layer 152 is formed by printing (eg, screen printing) a translucent matte ink (matte ink) over the entire region S except for the region T. Also, as shown in FIG. 12(a), the region T in this embodiment is composed of a plurality of circular patterns 153a to 153j arranged in ten rows along the longitudinal direction of the cover 150 (the left-right direction in FIG. 12) and arranged in a staggered pattern overall.

[0045] When the lighting device 2 of this embodiment is hung on the upper end of the display D and emits illumination light L1 from the lighting device 2, the area near the user U's hands (desk surface) is illuminated in the same manner as the lighting device 1 of the first embodiment, but the light path length of the light ray Lm emitted from the lighting device 2 toward the display D side is shorter than the light ray Lu emitted from the lighting device 2 toward the user U side (see Figs. 8 and 9). Therefore, the illuminance of the illumination light L1 is smaller on the user U side, but on the other hand, the degree of diffusion of the illumination light L1 is smaller on the display D side, and the occurrence of a yellow ring on the display D side becomes noticeable. Therefore, in this embodiment, the diameters of the circular patterns 153a-153j are configured to increase with increasing distance from the display D so that the illumination light L1 (light ray Lm side) emitted toward the display D side is more diffused and the illumination light L1 (light ray Lu side) emitted toward the user U side is more transmitted. In other words, the cover 150 is attached to the case 101 so that the circular pattern 153a side where the proportion of the area S is large (the proportion of the area T is small) is the hooking portion 200 side, and the circular pattern 153j side where the proportion of the area S is small (the proportion of the area T is large) is the user U side. More specifically, in this embodiment, the diameters of the circular patterns 153a and 153b are set to 0.2 mm, the diameters of the circular patterns 153c and 153d to 0.3 mm, the diameters of the circular patterns 153e and 153f to 0.35 mm, the diameters of the circular patterns 153g and 153h to 0.45 mm, and the diameters of the circular patterns 153i and 153j to 0.5 mm. The intervals between the circular patterns 153a to 153j in the short-side direction of the cover 150 (the vertical direction in FIG. 12) (i.e., the intervals between each row) are set to 0.7 mm, and the intervals between the circular patterns 153a to 153j in the long-side direction are set to 1.5 mm.

[0046] In this manner, in the cover 150 of this embodiment, the diameters of the circular patterns 153a to 153j are configured to gradually increase with increasing distance from the display D, and the ratio of area T (circular patterns 153a to 153j) to area S per unit area increases with increasing distance from the display. Therefore, according to the lighting device 2 of this embodiment, the cover 150 diffuses the illumination light L1 (light ray Lm side) emitted toward the display D side, and the amount of light that passes through the illumination light L1 (light ray Lu side) toward the user U side increases, making it possible to achieve uniform illumination while suppressing the occurrence of yellow rings.

[0047] (Illuminance evaluation of lighting device 2) FIG. 13 shows the results of evaluating the light distribution characteristics (illuminance) when the lighting device 2 is arranged as shown in FIG. 8 and the multiple white LED chips 115 and the multiple warm white LED chips 116 are turned on at maximum illuminance (i.e., the maximum power supply (4.5 W) of the USB port of a computer). FIG. 13(a) shows the evaluation result according to the JIS standard A type standard (JIS C8112), and FIG. 13(b) shows the evaluation result according to the Illuminating Engineering Society of North America standard. As shown in Figure 13(a), when the illumination range R1 is a sector-shaped area in front of the lighting device 2 on the desk surface, the illuminance of the illumination light L1 from the lighting device 2 is 155 to 210 lux on 1 / 3 of the circumference with a radius of 50 cm in front (on the outer arc) and 320 to 430 lux on 1 / 3 of the circumference with a radius of 30 cm in front (on the inner arc), which satisfies the JIS Type A standard (150 lux or more on 1 / 3 of the circumference with a radius of 50 cm in front of the lighting device 1, and 300 lux or more on 1 / 3 of the circumference with a radius of 30 cm in front). As shown in FIG. 13(b), when the illumination light L1 from the illumination device 2 is set to an illumination range R2 on the desk surface, which is a rectangular range of 41 cm to 10 cm in front of the illumination device 1 and 36 cm to the left and right, the uniformity (minimum illuminance / maximum illuminance) in the illumination range R2 is 260 lux / 500 lux=52%, which satisfies the uniformity standard (33% or more) of the Illuminating Engineering Society of North America. As in the first embodiment, the uniformity varies somewhat depending on product variations and measurement conditions, but it is desirable for the illumination range R2 to be 40% or more, and more desirably 45%. In the case of the configuration of the illumination device 2 of this embodiment, the uniformity in the illumination range R2 is considered to vary in the range of 45 to 55%. Thus, like the illumination device 1 of the first embodiment, the illumination device 2 of this embodiment provides illumination light L1 that is gentle on the eyes and has little unevenness in illuminance within the illumination ranges R1 and R2 on the desk surface.

[0048] In this embodiment, the diameters of the circular patterns 153a and 153b are set to 0.2 mm, the diameters of the circular patterns 153c and 153d to 0.3 mm, the diameters of the circular patterns 153e and 153f to 0.35 mm, the diameters of the circular patterns 153g and 153h to 0.45 mm, and the diameters of the circular patterns 153i and 153j to 0.5 mm. However, this is not limited to the above configuration, and the number, size and arrangement of the multiple circular patterns can be changed as appropriate depending on the strength of the yellow ring and the required specifications (light amount and uniformity of the illumination light), etc.

[0049] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0050] 1: Lighting equipment 10: Lighting equipment (conventional) 11: Case (conventional) 12: Substrate (conventional) 15: LED chip (conventional) 16: Reflective mirror (conventional) 100: Main body 101: Case 101a: Output aperture 102: Cover 103: Diffuser 104: Side cover 105: Light guide plate 106: Sensor cover 110: Light source unit 112: Substrate 115: White LED chip 116: Warm white LED chip 117: Color LED chip 118: MPU 120: Face LED board 122: Substrate 125: White LED element 130: MPU board 131: MPU 132: First sensor 133: Second sensor 134: 3rd sensor 135: 4th sensor 136: LED driver 137: LED driver 139: USB connector 150: Cover 151: Base material 152: Light diffusion layer 153a:Circular pattern 153b:Circular pattern 153c:Circular pattern 153d:Circular pattern 153e:Circular pattern 153f:Circular pattern 153g :Circular pattern 153h: Circular pattern 153i: Circular pattern 153j:Circular pattern 200:Latching part 210: Weight section 215: Rotation axis 230: Arm section 232: Tongue 235: Rotation axis C: USB cable D: Display D1: Display D2: Display D3: Display Lo: Illumination light (conventional) L1: Illumination light L2: Illumination light L3: Illumination light U:User S :Area T :Area

Claims

1. An illumination device that is attached to an upper end of a display of a computer placed on a desk surface and irradiates illumination light toward the desk surface, comprising: a light source unit including a substrate extending substantially horizontally along an upper end of the display and a plurality of LED elements disposed on a surface of the substrate and emitting the illumination light; a main body portion that houses the light source portion and extends substantially horizontally along an upper end portion of the display; a hook portion that supports the main body portion so as to be positioned forward of a surface of the display and that hooks onto an upper end portion of the display; Equipped with the main body portion faces the desk top surface and has a rectangular emission opening through which the illumination light from the plurality of LED elements is emitted, and a cover member that is disposed on an optical axis of the plurality of LED elements and through which the illumination light from the plurality of LED elements passes; the cover member has a first region through which the illumination light passes as is and a second region through which the illumination light passes while being diffused, The ratio of the first area to the second area per unit area increases with increasing distance from the display. A lighting device characterized by:

2. 2. The lighting device according to claim 1, characterized in that, when the emission opening is disposed at a height of 40 cm from the desk surface and the plurality of LED elements are caused to emit light with a power consumption of 4.5 W, the illuminance on a 1 / 3 circumference with a radius of 50 cm in front of the lighting device on the desk surface is 150 lux or more, and the illuminance on a 1 / 3 circumference with a radius of 30 cm in front of the lighting device is 300 lux or more.

3. The cover member is composed of a transparent base material and a matte ink laminated on the back surface of the base material, The second region is formed by the matte ink.

3. The lighting device according to claim 1 or 2.

4. 4. The lighting device according to claim 1, wherein the plurality of LED elements are composed of a plurality of white LED chips that emit white light and a plurality of warm white LED chips that emit warm white light.

5. 5. The lighting device according to claim 1, wherein the lighting device is driven by power supplied from a USB port of the computer.

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