JP2013246956A - Lighting unit, and desk system with illumination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting unit excellent in energy conservation and routing of wiring, capable of lighting a work area on a desk as well as a work space where there is a worker, and to provide a desk system with illumination using the lighting unit.SOLUTION: Luminous flux emitted from LEDs 2 is guided while it is totally reflected between a first primary surface 11 and a second primary surface 12, and luminous flux reflected and diffused with a light path deflection means 15 and deviated from a total reflection angle can illuminate a designated work area via a first diffusion plate 5 by being emitted from the first primary surface 11 as first illumination light. On the other hand, luminous flux deviated from the total reflection angle among the light incident to the second primary surface 12 transmits the second primary surface 12, and then, is given directivity while passing through a prism sheet 6, and further, is emitted in nearly a vertical direction as second illumination light through a second diffusion plate 7. Therefore, the luminous flux can illuminate a ceiling or the like in the room where the lighting unit U is arranged, whereby, the lighting unit U with high efficiency can be attained as a whole.

Description

  The present invention relates to an illumination unit and an illuminated desk system, and more particularly to an illumination unit and an illuminated desk system that can illuminate a work area on a desk and illuminate a work space where an operator is present.

  Conventionally, fluorescent lamps and incandescent lamps have been widely used as illumination light sources for lighting fixtures such as lighting stands. Here, the fluorescent lamp generally converts electrical energy into visible light, infrared light, and ultraviolet light, and uses the emitted visible light as illumination. However, there is a problem that heat loss that occurs at that time is inevitable, power consumption is large, and it is difficult to maintain a long life. In addition, since the fluorescent lamp requires an inverter and a ballast as a lighting circuit, there is a problem that it is difficult to reduce the size and weight. On the other hand, incandescent lamps convert electric energy into visible light and infrared light, and the emitted visible light is used as illumination. However, the heat loss is larger than that of fluorescent lamps. Has a problem of high power consumption and shorter life than fluorescent lamps. Therefore, fluorescent lamps and incandescent lamps do not necessarily have sufficient characteristics as light sources for lighting stands, but they have been used extensively because they are relatively inexpensive.

  On the other hand, in recent years, lighting devices using LEDs (Light Emitting Diodes), which have long life and low power consumption and are environmentally friendly, have been put into practical use along with improved luminous efficiency and increased light emission. It's getting on. Since the blue LED chip was developed, a white LED light source that emits white light by combining the blue LED chip and a phosphor that is excited by light from the LED chip and emits excitation light of a predetermined wavelength, A white LED light source that synthesizes white light using three primary color LED chips of a blue LED chip, a green LED chip, and a red LED chip has been developed.

  For this purpose, an LED illumination unit in which this white LED light source is disposed is used as an illumination unit for an indoor lighting fixture. In particular, as an illumination unit for an illumination stand, an attempt has been made to use an LED light source that consumes less power and generates less heat. For example, an illumination unit for an illumination stand that uses a plurality of LEDs and a light guide plate has been proposed. Yes.

  By the way, the problem of power supply is becoming more serious both in Japan and overseas. As described above, in offices and the like, LED lighting fixtures that can efficiently illuminate with low power consumption are being introduced, but further energy saving technology promotion is desired. However, when desk lighting and room lighting are used in combination, there is a problem that a place where there is no worker and where no lighting is required is also illuminated.

  With respect to such a problem, Patent Document 1 is a lighting device provided in a desk system installed in an office or the like on the premise of personal lighting that does not use a ceiling lighting device that brightens the entire room, and each user is seated. There is disclosed a lighting device that can illuminate the use area of the desk and can achieve both power saving and improvement of user work and learning efficiency. However, in the lighting device of Patent Document 1, desk lighting and ceiling lighting use separate lighting modules, and thus a plurality of lighting modules are required to realize both lighting, and a holding mechanism, wiring, There is a problem that the control mechanism is complicated.

JP 2011-108428 A JP 2006-208582 JP JP 2011-100701

  For example, Patent Documents 2 and 3 have already known a single illumination unit that can illuminate illumination light on different sides. For example, in the electric signboard disclosed in Patent Document 2, the haze value (JIS K7136: 2000) is 2 in which at least one side end portion is a light incident surface and both surfaces substantially perpendicular to the light incident surface are light emission surfaces. % Of the light guide plate and a backlight for an electric signboard so as to be composed of a light source disposed at at least one side end of the light guide plate, and the light emitted from the light source is emitted from both sides of the light guide plate. It can be done.

  Moreover, in the display device disclosed in Patent Document 3, a double-sided light-emitting panel is formed by a light-transmitting substrate member, and a large number of light reflecting means are formed as reflective dots by dot printing on the light irradiation surfaces on both sides of the substrate. It has. The reflective dots formed on one side and the reflective dots formed on the other side are shifted so that they do not overlap, and the reflected light is reflected and reflected using each reflective dot. Irradiation light can be transmitted from the opposite light irradiation surface side to emit light on both sides.

  Although both of Patent Documents 2 and 3 are illumination modules that emit light on both sides, the light distribution characteristics of the light emitted from both sides are the same, so the work area on the desk is illuminated and the work space where the worker is located is illuminated. Therefore, it can be said that it is not suitable for use as a lighting unit that is expected to have different light distribution characteristics.

  The present invention has been made in view of the above circumstances, and is excellent in energy saving and wiring management, can illuminate a work area on a desk, and can illuminate a work space where an operator is present, and uses the same. The purpose is to provide a desk system with lighting.

The lighting unit according to claim 1 is a lighting unit that emits light in two directions in order to illuminate a work space where an operator is present and a work area used by the worker.
A light guide plate having a first main surface and a second main surface opposite to the first main surface, and a plurality of light emitting points disposed toward one side surface serving as an incident surface of the light guide plate A light-emitting element, optical path deflecting means is provided on either the first main surface or the second main surface, a first diffuser plate is disposed opposite to the first main surface, and the second main surface A second diffuser plate is arranged opposite to it,
The light emitted from the light emitting element enters the light guide plate from the incident surface, then guides the light through the light guide plate, and the first main surface and the second main surface through the optical path deflecting unit. It comes out from
The first illumination light irradiated from the first main surface side illuminates the work area, and at the same time, the second illumination light irradiated from the second main surface side illuminates the work space,
The angle formed by the maximum intensity direction of the first illumination light and the perpendicular of the first main surface is θ1max, and the angle formed by the maximum intensity direction of the second illumination light and the normal of the second main surface is θ2max. When satisfying, the following expression is satisfied.
θ1max> θ2max (1)

  According to the present invention, the work area can be illuminated brightly over a wide range by the first illumination light emitted from the illumination unit. This is called a task light function. Further, by illuminating the ceiling side by irradiating the second illumination light upward from the illumination unit, the work space where the worker is present can be illuminated brightly. This is called the ambient light function. In particular, by satisfying the expression (1), the maximum intensity direction of the first illumination light of the illumination unit can be tilted toward the operator side, so that the illumination unit does not interfere with the work. That is, a work area with sufficient illuminance can be secured widely even if it is arranged on the opposite side of the operator across the work area, while the maximum intensity direction of the second illumination light of the illumination unit is set to be vertical. By approaching, it becomes difficult for an operator to feel dazzling, and the entire space where the operator is present can be illuminated uniformly. In other words, since it is a single lighting unit that uses a single light-emitting element as the light source, it has excellent energy savings and wiring management, and has the optimal directivity for each outgoing light while realizing the task light function and ambient light function. By doing so, each function can be achieved efficiently. In particular, by emitting the light without reflecting on the second main surface, the total light utilization efficiency can be improved, which contributes to energy saving.

The illumination unit according to claim 2 is configured such that, in the invention according to claim 1, the first illumination light is irradiated in a direction away from the incident surface of the light guide plate facing the light emitting element. ,
When the direction away from the incident surface of the light guide plate with respect to the perpendicular of the first main surface is a positive direction of the angle θ1max, the following expression is satisfied.
10 ° <θ1max <60 ° (2)

  The first illumination light is irradiated in a direction away from the incident surface of the light guide plate facing the light emitting element, and the position where the illumination unit does not interfere with work, that is, the work area is sandwiched. If the light emitting surface on the first main surface side of the lighting unit is maintained in a horizontal state by arranging it on the opposite side of the worker and satisfying the formula (2), the work using the work area Since the light emitting surface on the first main surface side is difficult to be observed by the operator, it is possible to realize a lighting unit that is difficult for the operator to feel dazzling and is easy on the eyes. That is, if the value of the formula (2) exceeds the lower limit, the work area can be illuminated widely, and if the value of the formula (2) is lower than the upper limit, it can be said that the operator does not feel dazzling. Further, since the regular reflection direction of the first illumination light in the work area substantially matches the work area observation direction of the worker within a range satisfying the expression (2), the worker can illuminate the work area. Can be observed efficiently and brightly.

According to a third aspect of the present invention, the lighting unit according to the second aspect of the present invention satisfies the following expression.
10 ° <θ1max <35 ° (3)

  Even when the lighting unit is disposed at a height that does not obstruct the forward field of vision on the side farther than the worker who uses the work area, for example, about 90 cm, the upper limit of the expression (3) is not exceeded, Even when the light emitting surface on the first main surface side enters the field of view of the worker taking the working posture, it can be prevented from feeling dazzling. In addition, it is preferable that (theta) 1max can be changed optimally with the installation height of a lighting unit. That is, when the arrangement position of the illumination unit is high, it is desirable to reduce θ1max accordingly.

When the lighting unit according to claim 4 is the invention according to any one of claims 1 to 3, when the haze value of the first diffusion plate is Hz1, and the haze value of the second diffusion plate is Hz2, It satisfies the following formula.
Hz1 <Hz2 (4)

  The first diffusing plate may reduce the luminance unevenness of the light emitting surface while the directivity when the first illuminating light used for illuminating the work area is preserved in the directivity when emitted from the light guide plate. It is desirable to select. For this reason, it is desirable that the diffusivity of the first diffusion plate is minimized. On the other hand, it is desirable that the second illumination light used for illuminating the work space uniformly illuminates a wide range of the space. For this reason, it is desirable that the diffusivity of the second diffusion plate is relatively large. That is, it is preferable that the haze value of each diffusion plate satisfies the formula (4).

The illumination unit according to claim 5 is the invention according to any one of claims 1 to 4, wherein the spread angle of the first illumination light (the full width at half maximum of the intensity) is φ1, and the second illumination When the light spreading angle (full width at half maximum of intensity) is φ2, the following expression is satisfied.
φ1 <φ2 (5)

  By satisfying the expression (5), the work area can be illuminated intensively and efficiently with the first illumination light, while the wide illumination space is uniformly illuminated with the second illumination light. be able to. Accordingly, the lighting unit can achieve a high work efficiency because it can lighten the operator's hand while consuming low power, and by uniformly illuminating the surrounding work space, an environment in which the worker is less likely to get tired. realizable.

The illumination unit according to claim 6 is the invention according to any one of claims 1 to 5, wherein the irradiation direction of the first illumination light with respect to the perpendicular of the second main surface is the positive direction of the angle θ2max. The following expression is satisfied.
−5 ° <θ2max <5 ° (6)

  The maximum intensity direction of the second illumination light is made closer to the direction perpendicular to the surface direction of the second main surface so as to satisfy the expression (6), thereby the ceiling side of the room where the illumination unit is provided. Can be effectively illuminated, and at the same time, there is an advantage that it is difficult to feel dazzling even if the light emitting surface on the second main surface side of the illumination unit enters the field of view when an operator moves standing up.

The illumination unit according to claim 7 is the invention according to any one of claims 1 to 6, wherein the maximum intensity of the first illumination light is I1max and the maximum intensity of the second illumination light is I2max. The following expression is satisfied.
I1max> I2max (7)

  In order to provide an environment where it is easy to work while saving energy, the maximum intensity I1max of the first illumination light is made larger than the maximum intensity I2max of the second illumination light so as to satisfy the expression (7). Is desirable.

  The lighting unit according to claim 8 is the invention according to any one of claims 1 to 7, wherein the light-emitting element includes a plurality of point-like LEDs as the light-emitting points, and the point-like LEDs are arranged on the incident surface. It is characterized by being arranged discretely along.

  When the light-emitting element includes a plurality of point-like LEDs, it is possible to realize a lighting unit that is bright, has low radiant heat, has low power consumption, and is optimal for a small and lightweight lighting fixture. Whereas the illuminance may be low with a single LED, the illuminance can be increased by using a plurality of point-like light sources, and further arranged discretely along the incident surface, and a plurality of the point-like By mixing the light emitted from the LEDs in the light guide plate, it is possible to emit illumination light with little illuminance unevenness.

The illumination unit according to a ninth aspect is the invention according to any one of the first to eighth aspects, wherein the optical path deflecting means is discretely arranged on the second main surface and is parallel to the incident surface. The angle θv1 formed by the inclined surface on the incident surface side and the perpendicular of the second main surface in the V-groove or trapezoidal groove satisfies the following expression.
50 ° <θv1 <75 ° (8)

  According to this configuration, the direction in which the illumination light is efficiently inclined from the first main surface through the inclined surface on the incident surface side inclined at an angle θv1 larger than 45 ° with respect to the normal of the second main surface. Although it is a thin light guide plate, the illumination light emitted from the first main surface can be efficiently directed to irradiate the work area over a wide area.

  A lighting unit according to a tenth aspect is the invention according to any one of the first to eighth aspects, wherein the optical path deflecting means is discretely arranged on the first main surface and is parallel to the incident surface. It consists of a groove or a trapezoidal groove.

  Accordingly, it is possible to ensure a large angle θ1max in the maximum intensity direction of the illumination light emitted from the first main surface 11 side.

The illumination unit according to claim 11 is characterized in that, in the invention according to claim 8 or 9, the light path deflecting means has a diffusion angle σ (a full width at half maximum of diffusion intensity) satisfying the following expression. And
3 ° <σ <15 ° (9)

  By imparting diffusion characteristics to the slope on the incident surface side in the V-groove or trapezoidal groove, the illuminance distribution on the first diffusion plate surface, which is the light-emitting surface of the illumination unit, can be made uniform, and uneven brightness on the light-emitting surface can be obtained. Can be reduced. In particular, by satisfying the expression (9), the directivity of the illumination light can be secured while reducing the luminance unevenness of the light emitting surface. That is, when the value of the formula (9) exceeds the lower limit, the luminance unevenness of the light emitting surface can be suppressed. On the other hand, when the value of the formula (9) is lower than the upper limit, the directivity of the illumination light can be ensured. As a result, the luminance unevenness of the light emitting surface can be suppressed without significantly reducing the directivity of the light from the first main surface in the emission direction.

  A lighting unit according to a twelfth aspect is the invention according to any one of the first to eleventh aspects, wherein a large number of prisms are arranged in parallel between the second main surface of the light guide plate and the second diffusion plate. A prism sheet having a ridge line arranged in a direction parallel to an incident surface of the light guide plate is disposed.

  By disposing a prism sheet between the second main surface of the light guide plate and the diffusion plate, the light distribution angle of the illumination light that irradiates the ceiling side can be reduced, thereby reducing the luminance in the horizontal direction. Therefore, it is possible to realize ambient lighting that makes it difficult for the operator to feel dazzling. As shown in FIG. 23, the prism sheet is made of a transparent material, and is a side surface of a prism PS (provided that the ridge line RD is parallel to the incident surface of the light guide plate) made of a large number of triangular prisms arranged in parallel on the flat plate PT. Can be used. As the prism sheet, for example, BEF series of Sumitomo 3M Co. can be used.

The illumination unit according to claim 13 is the invention according to any one of claims 1 to 12, wherein the color temperature of the first illumination light is TK1, and the color temperature of the second illumination light is TK2. The following expression is satisfied.
TK1 ≠ TK2 (10)

  The first illumination light can clearly observe the work area by setting the color temperature high. On the other hand, the second illumination light can set the color temperature low to make the work space where the worker is located calm. That is, by making the color temperature TK1 of the first illumination light different from the color temperature TK2 of the second illumination light, it is possible to realize an environment in which an operator can easily work.

  The illumination unit according to claim 14 is the invention according to claim 13, wherein a filter that absorbs a specific wavelength band is disposed outside at least one of the first main surface and the second main surface. Features.

  In a double-sided illumination unit composed of one type of light source, light is emitted by inserting a color filter or the like as a filter that absorbs a specific wavelength band outside at least one of the first main surface and the second main surface. The color temperature can be easily controlled for each surface. In addition, the color temperature can be switched as necessary by inserting and removing the color filter.

  A desk system with illumination according to claim 15, a lighting unit according to any one of claims 1 to 14, a desk provided with a work area, and a support that supports the lighting unit on the back side of the desk The first illumination light illuminates the work area, and the second illumination light illuminates the upper part.

  By efficiently illuminating the work area of the desk with the first illumination light by disposing the lighting unit via the support on the upper side opposite to the operator of the desk having the work area At the same time, it is possible to realize an illuminated desk system that can brightly illuminate the work space with the second illumination light. Since the task light function and the ambient light function are combined, it is possible to eliminate or minimize the ceiling lighting while securing the illuminance necessary for the work, and to reduce the energy consumption for the room lighting.

  The desk system with lighting according to claim 16 is the invention according to claim 15, wherein the support is disposed between a pair of desks, and the lighting units that illuminate the respective work areas are opposed to each other. In this way, it is attached to the support.

  By disposing a support member that commonly supports the lighting unit that illuminates each work area between a pair of desks, an appropriate lighting environment can be provided while saving space.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in energy saving and wiring management, and while being able to illuminate the work area on a desk, the illumination unit which can illuminate the work space where an operator is, and a desk system with illumination using the same can be provided. .

It is a schematic sectional drawing which shows the outline | summary of the illumination unit which concerns on this invention. FIG. 3 is an explanatory enlarged sectional view showing only a part of the LED 2 and the light guide plate 1. FIG. 3 is an explanatory enlarged sectional view showing only a part of the LED 2 and the light guide plate 1. It is a schematic sectional drawing which shows the light-guide plate with which the illumination unit of FIG. 1 is provided. It is sectional drawing of the illumination unit of 1st Embodiment, and has shown the maximum intensity direction by the side of the 1st main surface, and the maximum intensity direction by the side of the 2nd main surface. It is the figure which looked at the direction which cut | disconnected the structure of FIG. 1 with the VI-VI line. It is sectional drawing of the illumination unit of 1st Embodiment, and has shown the representative light beam of 1st illumination light, and the representative light beam of 2nd illumination light. It is a figure which shows the angle intensity | strength characteristic of the ZY cross section of the illumination unit of 1st Embodiment. It is a schematic sectional drawing which shows the light-guide plate of 2nd Embodiment. It is a figure which shows the angle intensity | strength characteristic of the ZY cross section of the illumination unit of 2nd Embodiment. It is sectional drawing of the illumination unit of 3rd Embodiment. It is an expanded sectional view for explanation which takes out and shows only LED2 and a part of light guide plate of a 3rd embodiment. It is sectional drawing of the illumination unit of 3rd Embodiment, and has shown the representative light beam of 1st illumination light, and the representative light beam of 2nd illumination light. It is a figure which shows the angle intensity | strength characteristic of the ZY cross section of the illumination unit of 3rd Embodiment. It is sectional drawing of the illumination unit of 4th Embodiment, and has shown the representative light beam of 1st illumination light, and the representative light beam of 2nd illumination light. It is a figure which shows the angle intensity | strength characteristic of the ZY cross section of the illumination unit of 4th Embodiment. It is sectional drawing of the illumination unit of 5th Embodiment. It is a figure which shows the wavelength characteristic of an illumination unit by taking light intensity on a vertical axis | shaft and taking a wavelength on a horizontal axis. It is a perspective view of the desk system with illumination using a lighting unit. (A) It is a schematic explanatory drawing which shows the illumination outline of an illumination unit, (b) It is a schematic plan view which shows the illumination intensity distribution of the to-be-irradiated surface by an illumination unit. When the center of the lighting unit U is arranged at the origin (X = 0, Y = 0), (a) the illuminance distribution on the ceiling 30 surface and (b) the illuminance distribution on the work area OP surface are shown using contour lines. FIG. It is a figure which shows the example of the desk system 20A with illumination which two people can use facing each other. It is a perspective view which shows an example of a prism sheet.

  Embodiments of the present invention will be described below with reference to the drawings. Moreover, the same code | symbol is used about the same structural member, and detailed description is abbreviate | omitted suitably.

  The illumination unit according to the present invention is an illumination unit U having an irradiation surface that emits surface light. For example, as shown in FIG. 1, the first main surface 11 that emits surface light and the first main surface are opposed to the first main surface 11. Then, the light guide plate 1 having the second main surface 12 extending substantially in parallel, and the incident surface 13 of the light guide plate 1 extending in a direction intersecting the first main surface 11 and the second main surface 12. A light-emitting element 2 disposed to face one side surface, and guides light emitted from the light-emitting element 2 into the light guide plate 1, and the first main surface 11 and the second main surface 12. It is the lighting unit U for the lighting fixture which injects from. The first main surface 11 and the second main surface 12 are preferably used substantially parallel to each other, but the same effect can be obtained even when the first main surface 11 is deviated from parallel by about 5 degrees. That is, the term “substantially parallel” as used in this specification includes a case where they are tilted within 5 degrees. Also, when using the coordinate system in this specification, the center of the illumination unit is the origin, the gravitational acceleration direction is the Z direction, the direction toward the operator is the Y direction, and the direction perpendicular to the Z direction and the Y direction is the X direction. And

  The light guide plate 1 is a flat plate whose longitudinal direction is a direction perpendicular to the paper surface. The light guide plate 1 is a case together with the light emitting element 2 so as to expose the first main surface 11 on the lower surface side and the second main surface 12 on the upper surface side. 3 is housed integrally.

The first diffusion plate 5 is attached to the case 3 on the lower side of the first main surface 11 with a clearance from the first main surface 11, and on the upper side of the second main surface 12, a surface is provided. A second diffusion plate 7 is arranged through a prism sheet 6 on which a large number of small prisms are formed. When the haze value of the first diffusion plate 5 is Hz1 and the haze value of the second diffusion plate 7 is Hz2, the following expression is satisfied. The haze value is a value obtained by Td / Tt × 100 (%). However, Td: diffuse transmittance, Tt: total light transmittance (JIS K7136: 2000).
Hz1 <Hz2 (4)

  The light emitting element 2 only needs to be a light source that emits illumination light in the direction of the incident surface 13. For example, a plurality of point light sources (LEDs) arranged at intervals in the longitudinal direction of the incident surface 13 may be used. it can. Further, it is preferable to use an LED that emits white light with low power consumption and high emission intensity. Therefore, in the present embodiment, a white LED is used. Therefore, it replaces with the light emitting element 2, and demonstrates from now on as LED2. A plurality of LEDs 2 are arranged at substantially equal intervals (for example, a pitch of about 15 mm) in the longitudinal direction (direction perpendicular to the paper surface) of the substrate 21 accommodated in the case 3.

  The LED 2 is a white LED here, and emits white light by combining a plurality of blue LEDs and a phosphor (for example, a yellow phosphor) that is excited by light from the blue LED and emits excitation light of a predetermined wavelength. is there. In this case, a single planar light source having a yellow phosphor as a single plate may be used, but the width of the light emitting surface is preferably equal to or less than the width of the incident surface 13. The white LED may be a high color rendering LED that is a combination of a red LED, a blue LED, and a green LED. By using the high color rendering LED, it is possible to realize an illumination unit suitable for an application requiring high color reproducibility. Also, an illumination unit capable of adjusting the color temperature can be realized by alternately arranging two types of LEDs having different color temperatures and changing the emission intensity ratio of each LED.

  For example, the substrate 21 has a length approximately equal to the entire width in the longitudinal direction of the incident surface 13, and a plurality of chip-type LEDs 2 are mounted on the substrate 21 at a predetermined pitch. Thus, although the board | substrate 21 is united in the longitudinal direction, it is good also as a structure which divides | segments into several board | substrates and each is electrically connected. The board 21 is connected to a power supply circuit (not shown) arranged outside the lighting unit by a lead wire, and the brightness of the lighting unit is adjusted by adjusting the current flowing through the LED 2 with a brightness adjustment button provided in the electric circuit. The sheath chromaticity can be adjusted.

  2 and 3 are enlarged sectional views for explanation showing only the LED 2 and a part of the light guide plate 1. In FIG. 2, the incident surface 13 has a V-shaped groove shape, and has a first deflection plane 13 a and a second deflection plane 13 b that are inclined so as to approach the outer peripheral side of the LED 2 with the center in the thickness direction of the light guide plate 1 as a boundary. Therefore, the light emitted from the upper half of the LED 2 is refracted by the first deflection plane 13a and travels toward the second main surface 12, and the light emitted from the lower half of the LED 2 is refracted by the second deflection plane 13b. Then, it is directed to the first main surface 11.

  Here, the inclination angle θ of the first deflection plane 13a and the second deflection plane 13b is desirably up to 20 degrees. When tilted more than 20 degrees, the high intensity light emitted from the LED 2 does not become a total reflection component on the first main surface 11 and the second main surface 12, and is emitted at a position close to the LED 2, etc. Light extraction efficiency deteriorates. In addition, by tilting the first deflection plane 13a and the second deflection plane 13b by 20 degrees, low-intensity light emitted from the LED 2 at a radiation angle of 70 degrees (cosine 0.34) is incident, and at the incident plane 13 Fresnel reflection becomes relatively small at an incident angle of 50 degrees.

  On the other hand, from another viewpoint, the inclination angle θ of the first deflection plane 13a and the second deflection plane 13b is preferably equal to or larger than antan (t / (2L)). Here, with reference to FIG. 4, the thickness of the light guide plate is t (mm), and the distance from the incident surface 13 to the end surface opposite to the incident surface of the light guide plate 1 is L (mm). The width is 600 mm. As in the present embodiment, when t = 3 and L = 50, by setting atan (t / (2L)) = 1.7 degrees or more, the end surface on the side opposite to the incident surface 13 is directly reached. Since the guided light is lost and the high-intensity light is guided to the optical path deflecting means 15 (here, the slope of the V-groove or trapezoidal groove), the light can be extracted in the forward path as much as possible. be able to.

  Furthermore, it is preferable that all light beams (excluding edge diffracted light) incident from the first deflection plane 13a and the second deflection plane 13b are incident on the first main surface 11 and the second main surface 12 that are incident first at a total reflection angle. . When the light guide plate 1 is formed of a material having a refractive index of 1.5, the refracted total incident light beam is inclined by the first principal plane 11 at an inclination angle θ of 6 degrees or less between the first deflection plane 13a and the second deflection plane 13b. Further, the second main surface 12 totally reflects. However, it is desirable that the first deflection plane 13a and the second deflection plane 13b are inclined at an inclination angle θ = 1.5 degrees or more. The incident surface 13 may be a flat surface.

  The light emitted from the LED 2 enters from the incident surface 13 and is guided through the light guide plate 1. That is, light is guided between the lower surface (first main surface 11) and the upper surface (second main surface 12) of the light guide plate 1 while being totally reflected, enters the optical path deflecting means 15, and deviates from the total reflection angle. The emitted light is emitted from the first main surface 11 or the second main surface 12 to emit light.

  By providing the optical path deflecting means 15, when surface emitting, strong light is emitted in an inclined direction different from the direction perpendicular to the surface direction of the main surface (first main surface 11) that emits the illumination light of the light guide plate 1. Irradiation is possible.

  More specifically, an optical path deflecting unit 15 is provided on either the first main surface 11 or the second main surface 12, and the optical path deflecting unit 15 is used to deflect a predetermined angle from the perpendicular direction of the first main surface 11. The illumination light is emitted. Referring to FIG. 3, an angle θ1max formed between the perpendicular line of first main surface 11 and the maximum intensity direction of emitted light preferably satisfies 10 ° <θ1max <60 °, and further 15 °. It is more preferable that <θ1max <35 °.

  The optical path deflecting means 15 shown in FIG. 3 employs a plurality of V grooves provided in the second main surface 12 and extending in the direction perpendicular to the paper surface. With this configuration, since the optical path deflecting means 15 is provided on the second main surface 12 opposite to the exit surface, the illuminance distribution of the light emitted from the first main surface 11 side can be made uniform. The illuminance distribution at the exit surface position can be made more uniform.

  Further, the V groove constituting the optical path deflecting means 15 has a first inclined surface V1A (inclined surface) on the incident surface side and a second inclined surface (joint surface) V2A that forms the V groove together with the first inclined surface V1A. By changing the inclination angle between the first slope V1A and the second slope V2A, it is possible to adjust the direction of the maximum peak intensity light of the illumination light that is deflected by a predetermined angle θ1max from the normal direction of the first main surface 11. it can.

  Here, the light guide plate 1 is made of a transparent material that transmits visible light (for example, PMMA having a refractive index of about 1.5: acrylic), and is formed by additionally processing the V-shaped optical path deflecting means 15. Alternatively, it can be molded integrally. In addition, the light guide plate 1 may be a glass material, acrylic other than PMMA, polycarbonate, a silicon resin sheet having plasticity, or the like depending on applications.

  By subjecting the transfer surface of the mold for forming the light guide plate 1 to a rough surface, the first inclined surface V1A can be roughened and a diffusion effect can be provided as a diffusing means. The diffusion angle σ in the light guide direction is preferably 3 to 15 degrees in full width at half maximum. When the pitch in the LED arrangement direction is large, the diffusivity of the slope serving as the optical path deflecting means may be an anisotropic diffusion surface having a larger diffusion angle in the LED arrangement direction.

  The light beam emitted from the LED 2 is guided while being totally reflected between the first main surface 11 and the second main surface 12, and the light beam reflected and diffused by the optical path deflecting means 15 and deviated from the total reflection angle is the first light beam. It is emitted as the first illumination light from the main surface 11, and the work area on the lower side can be illuminated via the first diffusion plate 5. Since the first diffusing plate 5 is arranged outside the first main surface 11, even if the optical path deflecting means 15 is composed of a plurality of V grooves that are discretely arranged, the exit surface (first main surface 11). It is possible to reduce the illuminance unevenness (brightness unevenness) of the illumination light in), and to realize a high-quality illumination unit U that is uniform and gentle on the eyes. As the first diffusion plate 5, a conventionally known resin diffusion plate or resin diffusion film having translucency can be used.

  On the other hand, the light beam that has deviated from the total reflection angle out of the light incident on the second principal surface 12 is given directivity while passing through the prism sheet 6 after passing through the second principal surface 12, and further, the second diffusion. Since the light is emitted as the second illumination light in a substantially vertical direction via the plate 7, the ceiling or the like in the room where the illumination unit U is provided can be illuminated, thereby realizing a highly efficient illumination unit U in total. it can. As the second diffusion plate 7, a conventionally known resin diffusion plate or resin diffusion film having translucency can be used.

(First embodiment)
Next, the light guide plate of the first embodiment will be further described.

  A light guide plate 1A shown in FIG. 4 is provided in the illumination unit U of the first embodiment shown in FIG. 1, and is made of a transparent body having a refractive index of 1 or more, for example, PMMA, PC having a refractive index of about 1.5. It has a length L of 50 mm, a width (perpendicular to the paper surface) of 600 mm, and a thickness t = 3 mm. The width can be arbitrarily changed according to the size of the work area.

  Further, a V-groove light beam branching portion 16 having an apex angle θi of 140 ° is provided on the incident surface 13. By providing such a V-groove-shaped (120 ° <θi <160 °) light beam branching portion 16 on the incident surface 13, the light emitted from the light emitting element in the vertical direction having the strongest intensity is incident on the incident surface. The light is refracted and branched in a direction toward the first main surface 11 and the second main surface 12 of the light guide plate 1A. The light guide plate 1A is guided while being reflected between the upper and lower main surfaces, and opposite to the incident surface 13. Before reaching the end face 14 on the side, the light can be efficiently taken out via the optical path deflecting means 15 and emitted from the first main surface 11 and the second main surface 12 to realize a highly efficient illumination unit.

  When the incident surface 13 is a flat surface, the light emitted perpendicularly from the LED 2 travels straight in the light guide plate 1A, resulting in a large loss.

  On the upper surface (second main surface 12) of the light guide plate 1A, a plurality of V-grooves (configured by slopes V1A and V2A) having a triangular cross section constituting the optical path deflecting means 15 are formed. Thus, by providing the optical path deflecting means 15 on the second main surface 12 facing the first main surface 11, the illuminance distribution on the first main surface 11 can be made uniform. In particular, in the illumination light irradiated on the work area, it is possible to alleviate the glare unique to the V-groove, and it is possible to realize high-quality illumination that is gentle on the eyes.

The V groove has a width Lv of 1 mm, an angle θv1 formed by the inclined surface V1A on the incident surface side of the V groove and the perpendicular of the second main surface 12 is 60 °, and the inclined surface V2A and the second main surface on the opposite side of the incident surface. An angle θv2 formed by 12 perpendicular lines is 30 °. It is desirable that the width Lv of the V-groove satisfies Lv <t (thickness). This is because if the width Lv is too large, the amount of light reflected from one slope of the V-groove and emitted outside the light guide plate increases, and the luminance unevenness of the illumination light becomes too large. It is desirable that the angle θv1 satisfies the following expression.
50 ° <θv1 <75 ° (8)

When the condition of the equation (8) is satisfied, the illumination light is efficiently inclined from the first main surface 11 to the perpendicular via the first inclined surface V1 inclined at an angle θv1 larger than 45 °. Can be injected in the direction. In addition, the illumination light reflected from the inclined surface V1A on the incident surface side before reaching the opposing end surface 14 of the illumination light incident from the incident surface 13 is emitted from the first main surface 11 in the maximum intensity direction. The angle θ1max formed with the first main surface 11 can be emitted in a direction satisfying the following expression.
10 ° <θ1max <35 ° (3)

  If the angle θ1max formed between the perpendicular line of the first main surface 11 and the maximum intensity direction of the emitted light satisfies the expression (3), the first main surface 11 is parallel to the work area (for example, the desk surface) (horizontal). However, the work area can be illuminated brightly over a wide range. In addition, since the high-intensity illumination light emitted from the first main surface 11 does not directly enter the eyes of the worker, the worker can observe the work area brightly without feeling dazzling.

  For example, as shown in FIG. 5, the illumination unit U of the first embodiment including the light guide plate 1 is in the direction of θ1max shown in the drawing from the first main surface 11 side, that is, the perpendicular direction of the illumination unit. The maximum intensity light is emitted in the direction inclined from the side to the worker side.

On the other hand, in FIG. 4, it is desirable that the angle θv2 satisfies the following expression.
80 ° <θv1 + θv2 <100 ° (11)

  When θv2 satisfies the expression (11), the light enters the light guide plate 1A from the incident surface 13, guides the light guide plate 1A, reaches the opposing end surface 14, and is reflected (or the end surface). The light that has passed through 14 is reflected by the reflection surface on the inner side of the frame 3 and again enters the light guide plate 1 </ b> A from the end surface 14), and can efficiently be emitted in the direction of θ1max> 0.

In the present embodiment, the V-groove slope V1A has a diffusion angle σ (full width of spread angle at which diffused light intensity becomes half value: full width at half maximum of diffuse intensity) set to about 5 ° to 7 °. However, in general, σ preferably satisfies the following formula.
3 ° <σ <15 ° (9)

  Thus, by making the V-groove slope V1A into a diffusing surface, it is possible to reduce unevenness in brightness on the exit surface on the first main surface 11 side of the lighting unit U. Even if the exit surface on the first main surface 11 side is directly viewed, it is possible to realize an illumination unit that does not feel dazzling. By limiting the diffusion angle σ to the range of the expression (9), the lighting unit can be provided with directivity.

  Further, in the present embodiment, the first diffusion plate 5 is disposed below the light guide plate 1A via an air layer of 0.5 mm. By arranging the first diffusion plate 5, it is possible to reduce illuminance unevenness and luminance unevenness on the exit surface of the illumination unit U on the first main surface 11 side. In particular, it is possible to realize a high-quality lighting unit that is easy on the eyes by suppressing the glare peculiar to the V groove.

  Further, FIG. 6 shows a view of the configuration of FIG. 1 viewed in the direction cut by the VI-VI line. When viewed in the normal direction of the exit surface, the plurality of inclined surfaces V1A in the V-groove of the light extraction means 15 shine brightly, and other than that, the stripe pattern appears dark, but the exit light passes through the first diffusion plate 5 Is diffused and the stripe pattern becomes difficult to see.

  In addition, since the light guided in the light guide plate 1A is incident and deflected by a relatively large V-groove having a maximum light guide direction size (width Lv) of 0.5 mm or more, scattered light or the like due to diffraction is deflected. By reducing and reliably reflecting the guided light, it is possible to emit while enhancing the directivity of the emitted light while ensuring high efficiency, thereby providing an illumination unit with increased illuminance in a desired illumination direction.

  The V groove constituting the optical path deflecting means 15 is not provided in the range of 5 mm from the incident surface 13. This is because if a V-groove is provided in the vicinity of the incident surface 13, bright lines are generated in the vicinity of the incident surface of the illumination unit U and the luminance distribution may be uneven. Further, in the present embodiment, as shown in FIG. 4, the V-groove is disposed in a region having a width of 5 mm or more from the incident surface 13 as the distance from the LED 2 side increases (P1, P2,... Pn ) Is gradually decreased, and it is particularly preferable that the pitch is gradually decreased in the range of 3.5 mm to 1 mm from the LED 2 side. By arranging the pitch of the V grooves so as to gradually decrease as the distance from the light source increases, the luminance distribution on the exit surface of the illumination unit can be made more uniform.

  On the other hand, the prism sheet 6 and the second diffuser plate 7 are arranged on the outer side of the second main surface 12 of the light guide plate 1A in order from the light guide plate side. In the light guide plate 1A in which the V-groove is arranged on the second main surface 12 described above, the light reflected from the V-groove inclined surface V1A and emitted from the first main surface 11 is refracted by the V-groove inclined surface V1A (or reflected by V2A). ) And light rays emitted from the second main surface 12 are mixed.

  In FIG. 7, representative light beams emitted from the first main surface 11 and the second main surface 12 are shown. Here, a solid line is an illumination light beam emitted from the first main surface 11, and from the incident surface 13. The light that has entered the light guide plate 1A is guided through the light guide plate 1A, totally reflected by the light source side inclined surface V1A of the V-groove, and then refracted by the first main surface 11 and from the light guide plate 1A to the first diffusion plate 5. Head to. Further, the light is diffused by the first diffusion plate 5 and emitted from the lower surface of the illumination unit U to illuminate the work area.

On the other hand, the dotted line is an illumination light beam emitted from the second main surface 12, and is guided through the light guide plate 1A, refracted at the light source side inclined surface V1A of the V groove (or reflected by V2A), and then from the light guide plate 1A to the prism sheet. It is injected toward 6. The exit angle from the light guide plate 1 </ b> A is a direction that is largely inclined from the normal direction of the second main surface 12, but substantially coincides with the normal direction of the second main surface 12 by being refracted by the prism sheet 6. After passing through the prism sheet 6, the light is diffused by the second diffusion plate 7 and emitted from the upper surface of the illumination unit U to illuminate the work space where the worker is present. That is, when the maximum intensity direction of light emitted from the second main surface 12 side of the illumination unit U is θ2max, it is preferable that the following expression is satisfied.
−5 ° <θ2max <5 ° (6)

Therefore, the following formula is satisfied.
θ1max> θ2max (1)

The first diffuser plate 5 is desirably a diffuser plate having a small diffusivity (haze value) in order to ensure directivity while reducing luminance unevenness of illumination light. For example, the product name LSE (Hz1 = 84%) of Kimoto is used. On the other hand, the second diffusing plate 7 is desirably a diffusing plate having a large diffusivity (haze value) in order to illuminate a wide space. For example, GM7 (Hz2 = 91%) of Kimoto is used. In any case, it is desirable that the following expression is satisfied.
Hz1 <Hz2 (4)

  FIG. 8 shows the angular intensity characteristics of the ZY section of the lighting unit of the present embodiment. The Z-axis positive direction is the direction from the lighting unit toward the desktop, that is, the work area, and the Z-axis negative direction is the work space where the operator is from the lighting unit, in other words, the direction toward the ceiling. Further, the positive Y-axis direction is the direction from the lighting unit toward the operator. A light beam emitted from the first main surface 11 side is L1, and a light beam emitted from the second main surface 12 side is L2. The same shall apply hereinafter.

From the graph of FIG. 8, the illumination light L1 in the working direction has the maximum intensity at θ1max = 25 °, and the angle range φ1 = 50 ° where the illuminance becomes ½. It can also be seen that the illumination light L2 directed toward the ceiling has a maximum intensity at θ2max = 0 ° and φ2 = 90 °. That is, φ1 <φ2 is satisfied, and it can be seen that the work area is efficiently illuminated and at the same time the space is widely illuminated. When the maximum intensity of illumination light irradiated from the first main surface 11 side is I1max and the maximum intensity of illumination light irradiated from the second main surface 12 side is I2max, the following expression is clearly satisfied.
I1max> I2max (7)

(Second Embodiment)
Next, the light guide plate of the second embodiment will be further described. FIG. 9 is a cross-sectional view of the light guide plate 1B according to the second embodiment.

  In the present embodiment, the optical path deflecting means 15 employs a plurality of trapezoidal grooves extending in the direction perpendicular to the paper surface provided in the second main surface 12 instead of the V-groove. The trapezoidal groove constituting the optical path deflecting means 15 includes a first inclined surface V1B (inclined surface) on the incident surface side, a second inclined surface (connecting surface) V2B inclined to the opposite side of the first inclined surface V1B, and a first inclined surface V1B. And a bottom surface V3B connecting the second slope V2B. As described above, by providing the second main surface 12 between the trapezoidal grooves and the bottom surface V3B parallel to the second main surface 12, it is possible to further reduce luminance unevenness.

  In the present embodiment, the angle θv1 formed by the inclined surface V1B on the incident surface side of the V-groove and the perpendicular of the second main surface 12 is 65 °, and the inclined surface V2B opposite to the incident surface and the perpendicular of the second main surface 12 The formed angle θv2 is 10 °. Moreover, the shape and arrangement pitch P of each trapezoid groove are equal. Other configurations are the same as those of the above-described embodiment.

FIG. 10 shows the angle intensity characteristics of the ZY cross section of the illumination unit of the present embodiment. The light emitted from the first main surface 11 side is denoted by L1, and the light emitted from the second main surface 12 side is denoted by L2. To do. From the graph of FIG. 10, it can be seen that the illumination light L1 in the working direction has the maximum intensity at θ1max = 35 °, and the illumination light L2 toward the ceiling has the maximum intensity at θ2max = 0 °. Also in the present embodiment, φ1 <φ2 is satisfied, and it can be seen that the work area is efficiently illuminated and at the same time the space is widely illuminated. When the maximum intensity of illumination light irradiated from the first main surface 11 side is I1max and the maximum intensity of illumination light irradiated from the second main surface 12 side is I2max, the following expression is clearly satisfied.
I1max> I2max (7)

(Third embodiment)
Next, the light guide plate of the third embodiment will be further described. FIG. 11 is a cross-sectional view of an illumination unit U including a light guide plate 1C according to the third embodiment. FIG. 12 is an enlarged view showing a part of the light guide plate 1C.

  As shown in FIG. 12, the optical path deflecting unit 15 according to the present embodiment employs a plurality of V grooves provided in the first main surface 11 and extending in the direction perpendicular to the paper surface. Specifically, the V-groove constituting the optical path deflecting means 15 is the first inclined surface V1C on the light source side (an inclined surface inclined so as to go from the first main surface 11 side to the second main surface 12 side as it is farther from the LED 2). And a second slope V2C that forms the V-groove together with the first slope V1C. The V-groove shape is the same as that in the first embodiment, but may be different. The second main surface 12 is a flat surface. Other configurations are the same as those of the above-described embodiment.

  In FIG. 13, representative light beams emitted from the first main surface 11 and the second main surface 12 are shown. Here, a solid line is an illumination light beam emitted from the first main surface 11. The light that has entered the light guide plate 1C from the incident surface 13 is guided while being totally reflected between opposing planes in the light guide plate 1C, refracted by the light source side inclined surface V1C of the V groove, and then the first diffusion from the light guide plate 1C. Head to board 5. Further, the light is diffused by the first diffusion plate 5 and emitted from the lower surface of the illumination unit U to illuminate the work area. Due to refraction at the V-groove slope V1C, the illumination light is refracted to an angle with a larger inclination θ1max (see FIG. 12) from the perpendicular direction of the first main surface 11.

  On the other hand, a dotted line in FIG. 13 is an illumination light beam that is emitted from the second main surface 12 and illuminates the work space where the worker is present. The light enters the light guide plate 1C from the incident surface 13 and is guided, and then is reflected from the V groove inclined surface V2C and emitted from the opposing second main surface 12. Most of the light beams emitted from the second main surface 12 are directed substantially perpendicular to the second main surface 12 by the prism sheet 6 and are emitted through the diffusion plate 7.

  As is clear from FIG. 12, the angle θ1max in the maximum intensity direction of the illumination light emitted from the first main surface 11 side is a larger angle than that in the first embodiment. Since the illumination unit U of the present embodiment can illuminate the work area from the back side with a larger inclination, a wide work area can be secured even if the arrangement height of the illumination unit is lowered.

Therefore, it can be said that the angle θ1max preferably satisfies the following expression in consideration of the above embodiment.
10 ° <θ1max <60 ° (2)

  FIG. 14 shows the angular intensity characteristics of the ZY cross section of the illumination unit of the present embodiment. The light emitted from the first main surface 11 side is L1, and the light emitted from the second main surface 12 side is L2. To do. From the graph of FIG. 14, it can be seen that the angle θ1max in the maximum intensity direction of the illumination light emitted from the first main surface 11 side is 55 °. It can also be seen that the angle θ2max = 5 ° in the maximum intensity direction of the illumination light emitted from the second main surface 12 side.

  According to the present embodiment, by arranging the V groove as the optical path deflecting means 15 on the first main surface 11, the light emitted from the second main surface 12, that is, the light that illuminates the work space where the worker is present. The maximum intensity can be about 60% of the maximum intensity of light that illuminates the work area. Accordingly, it is possible to realize illumination in which the working space where the worker is present is bright and bright at hand. A trapezoidal groove may be provided instead of the V groove.

(Fourth embodiment)
Next, the light guide plate of the fourth embodiment will be further described. FIG. 15 is a cross-sectional view of an illumination unit U including a light guide plate 1D according to the fourth embodiment. Here, with respect to the third embodiment, the second diffusion plate 7 is disposed directly opposite to the second main surface 12 without disposing a prism sheet outside the second main surface 12 of the light guide plate 1D. doing. The second diffusion plate 7 is desirably a diffusion plate having a higher diffusivity than that used in the first embodiment, for example, the product name LSE (Hz1 = 84%) manufactured by Kimoto. For example, the product name GM2 (Hz2 = 89%) manufactured by Kimoto can be used. Other configurations are the same as those of the above-described embodiment.

  FIG. 16 shows the angle intensity characteristics of the ZY cross section of the illumination unit of the present embodiment. The light beam emitted from the first main surface 11 side is L1, and the light beam emitted from the second main surface 12 side is L2. To do. The illumination light emitted from the first main surface 11 side has a maximum intensity at θ1max = 55 °. The light emitted from the second main surface 12 side has the maximum intensity in the direction perpendicular to the main surface. According to the present embodiment, by removing the prism sheet, it is possible to relatively increase the irradiation light to the work space where the worker is present.

(Fifth embodiment)
Next, the light guide plate of the fifth embodiment will be further described. FIG. 17 is a cross-sectional view of an illumination unit U including a light guide plate 1E according to the fifth embodiment. In the present embodiment, a filter 8 for changing the color temperature of the illumination light is arranged between the prism sheet 6 and the second diffusion plate 7 as compared with the first embodiment.

  In FIG. 18, the light intensity is plotted on the vertical axis, the wavelength is plotted on the horizontal axis, the emission wavelength characteristic of the LED 2 is shown by a solid line, and the wavelength characteristic of the illumination light emitted from the second main surface 12 side and illuminating the work space where the worker is present. Is indicated by a dotted line. The filter 8 is a wavelength absorption filter that absorbs approximately 20% of the substantially blue wavelength band including 450 nm, and the illumination intensity that has passed through the filter 8 has a reduced wavelength intensity of the blue band as shown in FIG. Thereby, the color temperature of illumination light can be reduced (TK1 ≠ YK2).

  The work area is preferably illuminated with a high color temperature in order to increase the visibility of the work object, and it is even better if the color is high. On the other hand, there is a case where lighting in a space where a worker is present (inside the room) is preferred because the one having a lower color temperature is more settled. By using the filter 8, it is possible to realize an illumination unit having different color temperatures of illumination light on both sides even when the LED 2 having a single color temperature is used. The filter 8 is not limited to an absorption filter that absorbs a specific wavelength, but may be any filter that can convert the wavelength characteristics of illumination light, such as a fluorescent filter. That is, the absorption wavelength band of the filter is arbitrary, and the color temperature of the upper illumination light may be increased. Instead of providing the filter 8, a filter that absorbs a predetermined wavelength band may be provided on the first main surface 11 side. You may provide the structure which can insert / extract a filter.

  The lighting unit U of the above-described embodiment can be suitably applied to a lighting fixture that illuminates a work area. For this purpose, a desk system with lighting provided with the lighting unit will be described with reference to the drawings.

  FIG. 19 is a perspective view of an illuminated desk system 20 including an illumination unit U. In FIG. 19, the illuminated desk system 20 includes four legs 21 standing on the floor, a desk board 22 supported horizontally at the upper end of the legs 21, and an upper side behind the desk board 22. A support frame (support) 23 fixed so as to extend to the illumination unit U, and an illumination unit U held by the support frame 23. The leg portion 21 and the desk board 22 constitute a desk. An operator (not shown) is positioned on the front side and works on the desk board 22 as a work area OP. The lighting unit U is arranged on the side farther from the worker than the center of the work area OP.

  The lighting unit U supports the LED substrate 21 on the back side (the left side in FIG. 1 is the side far from the operator) and the first main surface 11 so as to be substantially parallel to the desk plate 22 (working area OP). It is fixed to the frame 23. Thereby, the intensity | strength maximum direction of the illumination light inject | emitted below from the 1st main surface 11 side faces the work area | region OP so that an operator may be approached.

  As described above, the illumination unit U emits the maximum intensity illumination light toward the user side in a tilted direction as indicated by the angle θ1max in FIG. Also, the reflected light RF reflected from the desk board 22 enters the operator's eyes (EY).

  As shown in FIG. 20B in which the degree of brightness is displayed in shades, the illuminance near the lighting unit U of the illuminated desk system 20 is high. Further, the front side (the positive side of the Y axis) has an asymmetric illumination distribution with higher illuminance than the back side (the negative side of the Y axis).

  The illuminance distribution of the illuminance Ry on the X axis is substantially symmetric with respect to the origin, but the illuminance distribution of the illuminance Rx on the Y axis is asymmetric, and the X is a positive (+) region, that is, on the observer side. It can be seen that the area is brightly illuminated as compared to the negative (−) area of Y, that is, the back side of the lighting unit U.

  Therefore, the illumination light emitted from the first main surface 11 side of the illumination unit U can illuminate the center side of the work area OP brightly even if the center of the illumination unit U is behind the work area OP. it can. Therefore, the worker not only does not disturb the lighting unit U itself, but also the regular reflection component of the illumination light on the work surface easily enters the eyes EY of the worker. You can work while observing.

  On the other hand, the illumination light emitted from the second main surface 12 side of the illumination unit U travels in a substantially vertical direction and illuminates the ceiling 30. Accordingly, it is possible to illuminate the room where the illuminated desk system 20 is provided by the effect of indirect illumination without directly entering the eyes of the operator.

  In the desk lighting system 20, FIG. 21A shows the illuminance distribution on the surface of the ceiling 30 when the center of the lighting unit U is arranged at the origin (X = 0, Y = 0), and the illuminance distribution on the work area OP surface is shown. In FIG. 21B, each is shown using contour lines. As shown in FIG. 21A, the illuminance distribution on the surface of the ceiling 30 is brightest immediately above the center of the lighting unit U (X = 0, Y = 0), and the illuminance is reduced approximately isotropically. That is, it is possible to illuminate the work space where the worker is present without being biased around the lighting unit U.

  On the other hand, as shown in FIG. 21B, the illuminance distribution on the work area OP surface is intensively illuminated in the work area OP, that is, the area of Y> 0. This area is hardly illuminated. As a result, the work area OP can be illuminated brightly and efficiently, and on the other hand, by not irradiating light to the area where illumination light is unnecessary, power consumption can be reduced as a lighting device.

  FIG. 22 is a diagram showing an example of an illuminated desk system 20A that two people can use face to face. Here, the two desk plates 22A and 22B are supported by the six legs 21, and the two lighting units U1 and U2 are supported by the support frame 23 erected from between the desk plates 22A and 22B. The LED substrate 21 side is fixed back to back. That is, the support frame 23 and the central leg 21 are common.

  In the conventional stand illumination, since the area immediately below it is brightest, the efficiency is poor because the area between the two worker's work areas, that is, the outside of each work area, is brightest. In the desk system with illumination 20A, the desk board 22A and the desk board 22B illuminate brightly to the hand of the work area where the worker works. The lighting unit U1 and the lighting unit U2 may be independently provided with a power switch. By providing the power switch independently, it is possible to illuminate only the necessary desk side, so that power consumption can be reduced.

  Table 1 summarizes the numerical values of the claims according to the first to fifth embodiments.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. For example, the lighting unit U is attached to the wall surface, the work light placed along the wall surface is illuminated with the illumination light emitted from the first main surface 11 side, and the illumination light emitted from the second main surface 12 side is used. The work space may be illuminated by irradiating the wall and ceiling.

1-1E Light guide plate 2 Light emitting element (LED)
DESCRIPTION OF SYMBOLS 3 Case 4 Reflecting plate 5 1st diffuser plate 6 Prism sheet 7 2nd diffuser plate 8 Filter 11 1st main surface 12 2nd main surface 13 Incident surface 14 End surface 15 Optical path deflecting means 16 Light beam branching part 20, 20A Illuminated desk system V1A, V1B, V1C, V1D, V1E 1st slope V2A, V2B, V2C, V2D, V2E 2nd slope U, U1, U2 Lighting unit

Claims (16)

An illumination unit that emits light in two directions to illuminate a work space where an operator is present and a work area used by the worker,
A light guide plate having a first main surface and a second main surface opposite to the first main surface, and a plurality of light emitting points disposed toward one side surface serving as an incident surface of the light guide plate A light-emitting element, optical path deflecting means is provided on either the first main surface or the second main surface, a first diffuser plate is disposed opposite to the first main surface, and the second main surface A second diffuser plate is arranged opposite to it,
The light emitted from the light emitting element enters the light guide plate from the incident surface, then guides the light through the light guide plate, and the first main surface and the second main surface through the optical path deflecting unit. It comes out from
The first illumination light irradiated from the first main surface side illuminates the work area, and at the same time, the second illumination light irradiated from the second main surface side illuminates the work space,
The angle formed by the maximum intensity direction of the first illumination light and the perpendicular of the first main surface is θ1max, and the angle formed by the maximum intensity direction of the second illumination light and the normal of the second main surface is θ2max. A lighting unit characterized by satisfying the following formula:
θ1max> θ2max (1) The first illumination light is irradiated in a direction away from the incident surface of the light guide plate facing the light emitting element;
2. The illumination unit according to claim 1, wherein the following formula is satisfied when a direction away from the incident surface of the light guide plate with respect to the perpendicular of the first main surface is a positive direction of the angle θ1max.
10 ° <θ1max <60 ° (2) The lighting unit according to claim 2, wherein the following expression is satisfied.
10 ° <θ1max <35 ° (3) The lighting unit according to claim 1, wherein the following expression is satisfied when the haze value of the first diffusion plate is Hz1 and the haze value of the second diffusion plate is Hz2.
Hz1 <Hz2 (4) When the spread angle of the first illumination light (the full width at half maximum of the intensity) is φ1, and the spread angle of the second illumination light (the full width at half maximum of the intensity) is φ2, the following expression is satisfied. The lighting unit according to any one of claims 1 to 4, wherein
φ1 <φ2 (5) The following expression is satisfied when the irradiation direction of the first illumination light is a positive direction of the angle θ2max with respect to the perpendicular line of the second main surface: The lighting unit described.
−5 ° <θ2max <5 ° (6) The illumination according to any one of claims 1 to 6, wherein the following expression is satisfied, where I1max is the maximum intensity of the first illumination light and I2max is the maximum intensity of the second illumination light. unit.
I1max> I2max (7)   The light emitting element includes a plurality of point LEDs as the light emitting points, and the point LEDs are discretely arranged along the incident surface. Lighting unit. The optical path deflecting means includes a V-groove or a trapezoidal groove that is discretely arranged on the second main surface and is parallel to the incident surface. The inclined surface of the V-groove or the trapezoidal groove on the incident surface side and the second groove The illumination unit according to any one of claims 1 to 8, wherein an angle θv1 formed with a perpendicular to the main surface satisfies the following expression.
50 ° <θv1 <75 ° (8)   9. The illumination unit according to claim 1, wherein the optical path deflecting unit includes a V-groove or a trapezoidal groove that is discretely arranged on the first main surface and is parallel to the incident surface. . 11. The illumination unit according to claim 9, wherein the optical path deflecting unit has a diffusion angle σ (a diffusion intensity full width at half maximum angle) satisfying the following expression.
3 ° <σ <15 ° (9)   Between the second main surface of the light guide plate and the second diffuser plate, a prism sheet is arranged in which a large number of prisms are arranged in parallel and the ridges thereof are arranged in a direction parallel to the incident surface of the light guide plate. The lighting unit according to claim 1. The illumination according to any one of claims 1 to 12, wherein the following equation is satisfied when the color temperature of the first illumination light is TK1 and the color temperature of the second illumination light is TK2. unit.
TK1 ≠ TK2 (10)   The illumination unit according to claim 13, wherein a filter that absorbs a specific wavelength band is disposed outside at least one of the first main surface and the second main surface.   The lighting unit according to claim 1, a desk provided with a work area, and a support body that supports the lighting unit on the back side of the desk, wherein the first illumination light is the A desk system with illumination, wherein a work area is illuminated, and the second illumination light illuminates the top.   The said support body is arrange | positioned between a pair of said desks, The said lighting unit which illuminates with respect to each said work area is attached to the said support body so that it may oppose. Illuminated desk system.

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