Patent Description:
As the conventional lens for illumination, that which constitutes a reading lamp, being installed in a backrest of a seat for use in a railroad vehicle, is known, for example. Generally, the reading lamp irradiates spot light on the hands of a passenger, and it is configured such that an LED as a light source and a lens to obtain a desired spot light distribution are housed in a spherical lamp body, respectively, the lamp body being rotatably supported in a housing to allow the irradiation direction of the spot light to be adjusted. For example, refer to Patent Document <NUM>.

Such a lens constituting a reading lamp is generally formed in a bowl shape, the bottom apex part thereof being opposed to an LED, as shown in <FIG> in Patent Document <NUM>. With such a lens, the light from the LED is taken in from the incident face provided in a recessed manner in the bottom apex part thereof into the inside thereof, and is condensed with the utilization of total reflection in the entire region in the inside of the lens outer periphery, being emitted from the emission face to obtain a predetermined light distribution.

However, needless to say the case when the passenger looks the reading lamp right in front of the lens, even in the case when the passenger looks it from an oblique direction crossing the central axis of the lens, the total reflection face, which is provided inside of the outer periphery of the lens, can be seen, thereby the passenger feeling uncomfortable glare, which has presented a problem.

Then, as a technology for reducing such uncomfortable glare in a lighting fixture designed on the assumption of use of a single lens of this type, there has already been proposed a lighting fixture technology with which a cylindrical hood is provided in front of the emission face of the lens, with glare-suppressing protrusions being formed in parallel on the inner circumferential surface of the hood. For example, refer to Patent Document <NUM>. In other words, this technology provides such a degree of depth with which the passenger is prevented from looking at the total reflection face inside of the lens through the irradiation opening located at the hood front end, and also suppresses the reflection toward the front that would be caused on the inner circumferential surface of the hood.

<CIT>
discloses a lens for lighting and lighting systems equipped with this. <CIT> discloses a lighting device. <CIT> discloses a LED lighting device and light guide lens. <CIT> discloses a lighting fixture.

However, with the conventional technology as disclosed in the above-described Patent Document <NUM>, there have been problems that the addition of a hood to the lens increases the number of parts and thus the number of man-hours for mounting them, thereby an increase in cost being caused. In addition, upsizing of the entire reading lamp has required a larger space for installing it, and there has also arisen a problem with its mountability in a limited space in a seat backrest.

The present invention has been made in view of the above-mentioned problems that are associated with the conventional technology, and is intended to provide a lens for illumination that can suppress uncomfortable glare with no need for adding an extra component; that can be compactly configured without bringing about an increase in size of the entire illumination device; and that also offers an improvement in mountability in a limited space therefor.

The subject matter of the present invention to achieve the above purpose is disclosed in the inventions as stated in the following respective items [<NUM>] to [<NUM>]:.

Next, the functions based on the aspects of the inventions that are stated in the above items [<NUM>] to [<NUM>] will be explained. According to the lens for illumination as stated in the above item [<NUM>], the lens body distributes the light incident thereon from a light source in a predetermined direction or range. The light from the light source is efficiently taken in into the inside of the lens body from the incident face, being provided in a recessed manner in the bottom apex part of the lens body. Herein, the light from the light source is advanced straight or bent to be passed through the inside of the lens body in accordance with the angle with respect to the incident face.

A part of the light, being passed through the inside of the lens body, does not reach the reflection face, being provided on the inner side of the outer periphery of the lens body, but is passed through a region further inside thereof, being emitted to the outside from the emission face, being provided at the upper end of the lens body. In addition, the light, being not have been directed straight to the emission face, will reach the reflection face to be totally reflected to thereby be condensed toward the emission face, and then emitted from the emission face to the outside.

With such a way of light distribution by the lens body, the incident face distributes the light, which could be directed toward the entire region of the reflection face, only in a predetermined range within the reflection face, being adjacent to the upper end side portion, following the emission face, and being closer to the bottom apex. Thereby, even if the viewer obliquely views the emission face of the lens body, the predetermined range, being located in the deeper area of the reflection face, will not come into view, so long as the viewer does not intentionally peek deep into the lens body. Therefore, within the total reflection face of the lens body, only the upper portion thereof, which will not reflect the light, will normally enter the visual field, whereby uncomfortable glare can be suppressed.

According to the lens for illumination as stated in the above item [<NUM>], the outer periphery of the lens body is provided with a plurality of side faces at least from the bottom apex part to a halfway point of the predetermined range, the cross section thereof having a polygonal shape. The light, being totally reflected by the reflection face, being provided on the inner side of each of the plurality of side faces, is emitted from the emission face in an irradiation range having an outline of the polygonal shape. With such a lens body, by giving, for example, a cross-sectional shape of quadrangle for the area from the bottom apex part to a halfway point of the predetermined range, distribution control to provide an illumination range of a quadrangle can be executed.

According to the lens for illumination as stated in the above item [<NUM>], the incident face of the lens body is comprised of a first incident face, being provided by a bottom face formed about the optical axis of the light source, and a second incident face, being provided by a side face surrounding the first incident face. The light incident from the first incident face is passed through an internal region of the lens body apart from the reflection face, and emitted to the outside from the inner region, being closer to the center, within the emission face.

In addition, the light incident from the second incident face is totally reflected in the predetermined range within the reflection face in the lens body, and emitted to the outside from the outer region around the inner region within the emission face. With such a lens body, the light from the light source can be efficiently utilized.

According to the lens for illumination of the invention, on the outside of the outer periphery of the lens body, there is provided a mounted part for use in locating the lens body with respect to a mounting portion of a mating component of the lens body. Thereby, the lens for illumination can be easily mounted in a lamp body of a reading lamp, or the like, being constituted thereby.

The above-described lens for illumination is suitable as a component constituting a reading lamp, being installed in a seat, as stated in the above [<NUM>].

With the lens for illumination according to the present invention, uncomfortable glare can be suppressed with no need for adding an extra component; a lens for illumination can be configured compactly without bringing about an increase in size of the entire illumination device; and its mountability in a limited space can be improved.

Hereinbelow, an embodiment representing the present invention will be explained with reference to the drawings.

<FIG> show one embodiment of the present invention.

A lens for illumination <NUM> according to the present embodiment includes a lens body <NUM>, which distributes light incident from the light source in a predetermined direction or range. With the present embodiment, the lens body <NUM> alone constitutes the lens for illumination <NUM>, however, the lens for illumination <NUM> may include the lens body <NUM> as a part of its structure.

As shown in <FIG>, the lens body <NUM>, which is the lens for illumination <NUM> itself, is in the shape of a solid bowl as shown in the figure, and is integrally formed of a transparent material, such as an acrylic resin or polycarbonate. The lens body <NUM> includes an incident face <NUM>, which is provided in a recessed manner in a bottom apex part thereof, and which receives the light from an LED <NUM>, the LED <NUM> being disposed opposite to the lens body <NUM> on the inner side of the bottom apex part as a light source (as shown in <FIG>); a reflection face <NUM>, which is provided on the inner side of the outer periphery, totally reflecting the light, having reached from the incident face <NUM>; and an emission face <NUM>, which is provided at the upper end of the lens body <NUM>, being opposed to the incident face <NUM> and emits the light, having reached from the reflection face <NUM>, to the outside.

As shown in <FIG>, in the lens body <NUM>, the incident face <NUM>, being located in the bottom apex part formed in a bowl shape, is comprised of a first incident face <NUM>, providing a bottom face formed about the optical axis of the LED <NUM>, and a second incident face <NUM>, providing a side face surrounding the first incident face <NUM>. The first incident face <NUM> is formed concentrically with the LED <NUM> about the optical axis L thereof, being provided with an arcuate section convexed toward the LED <NUM>. With the first incident face <NUM>, the light from the LED <NUM> is advanced straight or bent in the lens body <NUM> to be passed through an internal region of the lens body <NUM> apart from the reflection face <NUM>, and directed toward the inner region <NUM>, being closer to the center, within the emission face <NUM>.

The second incident face <NUM> is disposed such that it surrounds the emitting side of the LED <NUM>, being formed into a tapered section, thereby the diameter of the opening of the recessed part in the bottom apex part being made slightly larger than that of the outer periphery of the first incident face <NUM>. The second incident face <NUM> could be formed so as to refract the light from the LED <NUM> toward the entire region of the reflection face <NUM>, but, it is formed so as to distribute such light only in a later-described predetermined range <NUM> within the reflection face <NUM>, being adjacent to the upper end side portion (the upper portion <NUM>), following the emission face <NUM>, and being closer to the bottom apex part. Such light distribution control is previously established by setting the tapered angle of the second incident face <NUM>.

The reflection face <NUM> is provided as a critical angle reflection face with which the inner side of the outer periphery of the lens body <NUM> can totally reflect the light incident from the second incident face <NUM> toward the outer region <NUM>, being closer to the outside, within the emission face <NUM>. However, as described above, the light incident from the second incident face <NUM> will not reach the entire area of the reflection face <NUM>, but will limitedly reach the predetermined range <NUM>, being closer to the bottom apex part, within the reflection face <NUM>. Herein, specifically, the predetermined range <NUM> corresponds to a part of the reflection face <NUM> the level of which ranges from the bottom apex part to two thirds of the overall height of the lens body <NUM>.

The reflection face <NUM> provides a series of slanted curved surfaces, however, by making a specific design of the curved geometry and the inclination angle of the predetermined range <NUM>, the light, having been totally reflected, can be caused to be irradiated from the emission face <NUM> in a desired direction or with a desired light distribution characteristic. In the present embodiment, as shown in <FIG>, the predetermined range <NUM> of the reflection face <NUM> is provided as a series of slanted curved surfaces, causing the reflected light to be condensed in a direction approximately in parallel with the optical axis L of the LED <NUM>. In <FIG>, <FIG>, and <FIG>, the predetermined range <NUM> and the upper portion <NUM> located thereabove of the reflection face <NUM> are shown with a symbol being given on the right or left side alone, however, it should be noted that the portion to which the symbol refers extends over the entire periphery to the opposite side (the left or right side in the figure) where no symbol is given.

The emission face <NUM> is formed concentrically with the LED <NUM> about the optical axis L thereof, being provided with a curved section slightly bulged toward the outside, however, the emission face <NUM> may be formed in a flat surface. In the light distribution control in the present embodiment, the emission face <NUM> is divided into two regions, i.e., the inner region <NUM>, which is closer to the center, and the outer region <NUM> therearound, however, such division is not provided visibly. The inner region <NUM> provides a region where the light which has been made incident from the first incident face <NUM> is emitted directly to the outside. The outer region <NUM> provides a region where the light which has been made incident from the second incident face <NUM> and totally reflected in the predetermined range <NUM> of the reflection face <NUM> is emitted to the outside.

With the lamp body <NUM> of the later-described reading lamp <NUM>, as shown in <FIG> and <FIG>, the lens for illumination <NUM> is disposed ahead of the LED <NUM> through the holder <NUM>. Herein, the holder <NUM> is a member to hold the lens for illumination <NUM>, being in a cylindrical shape on the whole and provided with a flange <NUM> around the opening at the rear end, and is integrally formed of a synthetic resin, such as a plastic material, by using a mold. The holder <NUM> is located with a later-described LED substrate <NUM> by means of a locating means. More specifically, as shown in <FIG> and <FIG>, the flange <NUM> of the holder <NUM> is provided with a hole part <NUM>, into which a projection <NUM> of a base <NUM> is fitted.

On the outside of outer periphery of the lens body <NUM>, there is provided a shoulder part (mounted part) <NUM> to be located on the edge (mounting part) of the opening at the front end of the holder <NUM>. Within the reflection face <NUM> on the inner side of the outer periphery of the lens body <NUM>, the lower portion thereof, which is located closer to the bottom apex part than the shoulder part <NUM>, provides the predetermined range <NUM>. Strictly speaking, even the reflection face <NUM> is not capable of maintaining the total reflection in a portion thereof in which the shoulder part <NUM> is provided.

Within the outer periphery of the lens body <NUM>, the upper portion thereof, including the shoulder part <NUM>, is fitted to the front of the inner periphery of the opening part <NUM> of a later-described cover <NUM>, with the top face of the shoulder part <NUM> being engaged with a shoulder part <NUM>, which is provided on the the inner periphery of the opening part <NUM>. In such a state, the lens body <NUM> is held between the holder <NUM> and the opening part <NUM>. The lens body <NUM> is not contact with the holder <NUM> and the cover <NUM>, except for the shoulder part <NUM> and the outer periphery, being located thereabove.

In the case where, with the lens for illumination <NUM>, the orientation in which it is to be assembled with a later-described base <NUM> has been predetermined, the lens for illumination <NUM> and the holder <NUM> can be provided with means for mutually regulating the assembling orientation, 52a and <NUM>. More specifically, as shown in <FIG>, a notch 52a is provided for the lens for illumination <NUM> in one place in the shoulder part <NUM>. On the other hand, at the opening end of the holder <NUM>, a projection <NUM>, which is matched to the notch 52a, is provided in one place to assure the proper orientation of the notch 52a in assembling.

Any assembling orientation in which the projection <NUM> is not matched to the notch 52a will cause the projection <NUM> to interfere with the shoulder part <NUM> of the lens for illumination <NUM>, thereby the lens for illumination <NUM> being unable to be assembled with the holder <NUM>. With the lens for illumination <NUM> according to the present embodiment, the lens body <NUM> has the same sectional shape over the entire periphery except for the shoulder part <NUM>, and thus the orientation thereof is not particularly specified, however, for a later-described lens for illumination 50A, the notch 52a allows the orientation of the lens for illumination 50A to be easily determined, whereby assembling in an improper orientation can be prevented.

<FIG> show a lens for illumination 50A according to a modification, which, although the basic geometry and size thereof are common to those of the above-described lens for illumination <NUM>, is provided with a reflection face 520A, being different from that of the reflection face <NUM>. Note that the same potions as those of the lens for illumination <NUM> are provided with the same numerals, respectively, and repeated explanation thereof will be omitted here. The lens for illumination 50A according to the present modification is also disposed ahead of the LED <NUM> through the same holder <NUM>, being held in the lamp body <NUM>.

With the outer periphery of the lens body 51A of the lens for illumination 50A, the area at least from the bottom apex part to a halfway point of the predetermined range <NUM> is provided with a plurality of side faces <NUM>, with which the cross section orthogonal to the axis thereof has a polygonal shape. Then, the light, being totally reflected by the reflection face 520A, which is provided on the inner side of each side face <NUM>, is emitted from the emission face <NUM> in an irradiation range having an outline of the polygonal shape.

More specifically, the outer periphery of the lens body 51A is formed such that it has four side faces <NUM>, being inclined at an equal angle from the bottom apex part. With such reflection face 520A, which is provided on the inner side of each side face <NUM>, the light, having reached from the second incident face <NUM> of the incident face <NUM>, can be condensed into a quadrangle (square), whereby the light distribution from the emission face <NUM> can be performed for a quadrangle (square).

In the present modification, the lens for illumination 50A is configured to have four side faces <NUM>, being inclined at an equal angle from the bottom apex part within the outer periphery thereof toward four directions, however, the specific configuration of the lens for illumination 50A is not limited to that of the lens for illumination 50A according to the present modification, and the cross section of the lens body <NUM> may be specified to have a triangular shape or a five- or more-sided polygonal shape, for example.

Next, as shown in <FIG>, a reading lamp <NUM>, including the above-described lens for illumination <NUM>, 50A as a component, will be explained. The reading lamp <NUM> according to the present embodiment provides a lighting fixture, which includes a lamp body <NUM>, having a lens for illumination <NUM>, 50A and a light source, the lamp body <NUM> being mounted to a seat <NUM> through a bracket <NUM>. Hereinafter, the reading lamp <NUM>, which has been provided for the seat <NUM> in a railroad vehicle, will be explained, being used as an example.

As shown in <FIG> and <FIG>, the lamp body <NUM>, constituting a critical part of the reading lamp <NUM>, is provided by assembling the base <NUM>, with which the light source is disposed on the front side, with the cover <NUM>, which surrounds the light source on the front side of the base <NUM>, except for the irradiation range. The lamp body <NUM> is provided with a leg part, which is protruded on the side opposite to the emitting side of the light source, the tip thereof being engaged with a receiving part <NUM>, being provided for a later-described bracket <NUM> (see <FIG>). The lamp body <NUM> is supported by the bracket <NUM> such that the irradiation direction of the light source (the angle of the optical axis) can be adjusted with the tip of the leg part <NUM> being used as a fulcrum.

The base <NUM> has a disk-like shape on the whole, being integrally formed of a metal, such as an aluminum alloy by using such a method as die casting. The base <NUM> is made of a metal, being excellent in thermal conductivity, thereby serving also as a heat sink for dissipating the heat of the light source. More specifically, the base <NUM> has a disk-like shape on the front side, providing a mounting face <NUM>, while being opened on the back side to have a shallow-bottom dish-like shape, the leg part <NUM> being provided at the center on the back side of the mounting face <NUM>.

The leg part <NUM> is formed in a shaft-like shape with the tip thereof having a semispherical shape, being protruded toward the back side perpendicularly with respect to the mounting face. The tip of the leg part <NUM> is protruded toward the outside from the end edge of the peripheral wall <NUM> surrounding a space on the back side of the mounting face <NUM> (from the reference surface on the back side of the base <NUM>) by an amount equal to the height of the peripheral wall <NUM> when viewed from the side. In addition, the end edge of the peripheral wall <NUM> is provided with a flange <NUM>, being extended sidewise.

On the back side of the base <NUM>, there is radially provided a rib <NUM>, being extended four directions from the leg part <NUM> as the center and joined to the inner side of the peripheral wall <NUM>. Each rib <NUM> serves not only to reinforce the leg part <NUM> and the peripheral wall <NUM>, but also to function as a heat dissipation fin. In <FIG>, in one section between two adjacent ribs <NUM>, the peripheral wall <NUM> and the flange <NUM> are notched for use as a mounting space where related components, such as a power circuit board and a light source control circuit board, are disposed. In one portion of the flange <NUM>, which is opposed to this mounting space, there is provided a locating pin 24a, being protruded sidewise.

In addition, the base <NUM> is provided with a later-described engaged part <NUM>, which is used for snap-fit engagement with the cover <NUM>. The engaged part <NUM> is disposed along the outer periphery edge of the flange <NUM> in each location where the rib <NUM> is joined thereto. In the present embodiment, four engaged parts <NUM> are provided in correspondence to the four ribs <NUM>. More specifically, as shown in <FIG>, on the outer periphery edge of the flange <NUM>, the engaged part <NUM> is provided as an engaged groove, which is matched to the tip of an engaging claw of a later-described engaging part <NUM> of the cover <NUM>.

Next, the cover <NUM> is in a semispherical bowl-shape on the whole, being integrally formed of a synthetic resin, such as a plastic material, by using a mold. The cover <NUM> is formed of a synthetic resin, which is elastically deformable, and thus the later-described engaging part <NUM> can be elastically deformed. In the apex part of the outer periphery of the cover <NUM>, an opening part <NUM> for irradiation, matching to the irradiation range of the light source, is provided, being protruded in a cylinder-like manner. As shown in <FIG>, in the inner periphery of the opening part <NUM>, there is formed a shoulder part <NUM>, with which the diameter of the inner periphery is contracted toward the tip.

The cover <NUM> is assembled to the base <NUM> so as to cover the front side thereof. More specifically, an opening edge <NUM>, which is the outermost periphery of the cover <NUM>, is assembled to the base <NUM> so as to be fitted to the outer periphery edge of the flange <NUM>, and they are fixed to each other by snap-fit engaging the engaging part <NUM>, being provided for the cover <NUM>, with the engaged part <NUM>, being provided for the base <NUM>. Therefore, the inside diameter of the opening edge <NUM> of the cover <NUM> is designed to be that which is tightly matched to the outside diameter of the flange <NUM> of the base <NUM>.

The cover <NUM> is provided with the engaging part <NUM>, which is to be snap-fit engaged with the base <NUM>. Along the opening edge <NUM>, there are arranged a plurality of engaging part <NUM>, being disposed in the locations where they are matched to the engaged parts <NUM>. In the present embodiment, in correspondence with the four engaged parts <NUM>, the same number of engaging parts <NUM> are provided. More specifically, as shown in <FIG>, the engaging part <NUM> is provided along the opening edge <NUM> as an engaging claw, being fitted to the engaged groove, which is the engaged part <NUM>.

As shown in <FIG>, the engaging claw, which is the engaging part <NUM>, is formed such that the tip end of the claw is protruded toward the inside of the opening edge <NUM>. Herein, the back of the tip end is formed in a tapered shape such that it can elastically get on the engaged groove, which is the engaged part <NUM>. In addition, on both sides of the engaging part <NUM>, a pair of slits are notched such that a part of the outer periphery including the engaging part <NUM> can be elastically deformed toward the outside.

Next, the light source, which is disposed on the front side of the base <NUM> in the lamp body <NUM>, will be explained. The light source is constituted by a single LED <NUM>, which is a semiconductor light-emitting element, being mounted on an LED substrate <NUM>. The LED substrate <NUM> is formed in a square having a size allowing it to be accommodated within the area of the mounting face <NUM> of the base <NUM>. As the LED <NUM>, an LED chip of surface-mounting type is suitable, for example. Since the LED chip of such type is well known, the detailed explanation thereof will be omitted here. Simply put, it emits light within a predetermined angle of irradiation range about the optical axis thereof perpendicular to the LED substrate <NUM>. The luminescent color can be arbitrarily selected to suit to the application and type of the lighting fixture, however, for the reading lamp, white color is suitable.

The LED <NUM> is required to be held in a predetermined location on the front side of the base <NUM> in the lamp body <NUM>. Then, on the mounting face <NUM> of the base <NUM>, there is provided a locating means for locating the LED substrate <NUM> when disposing it. More specifically, as shown in <FIG>, on the mounting face <NUM>, three projections <NUM> are provided. On the other hand, in the peripheral area of the LED substrate <NUM>, there are provided hole parts <NUM>, into which the projections <NUM> are fitted, respectively. In the base <NUM>, an insertion hole <NUM> for inserting a wiring to supply power to the LED substrate <NUM> from the outside power supply is also provided (see <FIG>).

Between the mounting face <NUM> of the base <NUM> and the LED substrate <NUM>, a packing <NUM> in a ring shape is interposed, and the mounting face <NUM> of the base <NUM> and the LED substrate <NUM> are tightly contacted with each other through the packing <NUM>. The packing <NUM> is integrally formed of an elastic material, such as a non-conductive silicone rubber. The packing <NUM> is a member for protecting the circuit on the LED substrate <NUM> as a cushioning material, and for improving the dissipation performance by enhancing the adhesion between the base <NUM> and the LED substrate <NUM>.

The lamp body <NUM>, which provides a critical part of the above-described reading lamp <NUM>, is mounted to the seat <NUM> through the bracket <NUM>. Herein, the seat <NUM> is, for example, a two-occupant seat for use in a railroad vehicle, with which seat parts <NUM> and backrests <NUM> for two persons are arranged side by side in a line, as shown in <FIG>, and of both side parts on the upper end side of the respective backrests <NUM>, on the side part, being located on the outer side of the seat, the reading lamp <NUM> is provided. The reading lamp <NUM> is mounted to a frame in the inside of the backrest <NUM>, the opening part <NUM> thereof and the surrounding portion thereof being exposed to the outside of the cover of the backrest <NUM>.

As shown in <FIG>, the bracket <NUM> displaceably holds the lamp body <NUM>, having a housing part <NUM> for accommodating the lamp body <NUM> on the inner side thereof, and mounting parts <NUM> and <NUM> for fixing it to the frame in the inside of the backrest <NUM>. The housing part <NUM> is approximately in a cylindrical shape, surrounding the entire lamp body <NUM>, except for the opening part <NUM>, which provides the irradiation face of the lamp body <NUM>, and is formed of such a material as a metal.

The housing part <NUM> is comprised of an outer periphery wall <NUM>, being approximately in a cylindrical shape, a front wall <NUM>, covering the front-side opening of the outer periphery wall <NUM>, and a back wall <NUM>, walling up the back-face side opening of the outer periphery wall <NUM>. The inside diameter of the outer periphery wall <NUM> is set at a size that allows the lamp body <NUM> to be accommodated so as to be displaceable. The front wall <NUM> is formed such that the outer periphery of the cover <NUM> is slidably butted against the inner side, and is provided with a guide opening 63a, into which the opening part <NUM> is movably inserted.

The guide opening 63a is extended in a vertical direction, the inside diameter and the lateral width of the guide opening 63a at the upper and lower ends thereof being designed to be slightly larger than the outside diameter of the opening part <NUM>. In addition, the peripheral edge of the guide opening 63a may be provided as another part made of a synthetic resin rather than a metal. Further, the inner side of the peripheral edge of the guide opening 63a may be provided with a holding member made of such a material as moquette, which is to be elastically butted against the outer periphery of the cover <NUM>. When the lamp body <NUM> is to be accommodated in the housing part <NUM>, the front wall <NUM> can be mounted later.

The back wall <NUM> walls up the back side of the base <NUM> of the lamp body <NUM>, however, it is not formed in the shape of a disk on the whole, but is configured such that a plurality of supporting plates are radially extended from the central portion. In the central portion of this back wall <NUM>, there is provided a receiving part <NUM>, with which the tip of the leg part <NUM>, being provided on the back side of the base <NUM>, is engaged. As shown in <FIG>, the receiving part <NUM> is formed by fitting a gromet made of a resin into a round hole produced in the central portion of the back wall <NUM>. However, the configuration of the receiving part <NUM> is not limited to this, and any other configuration may be provided, so long as it allows the tip of the leg part <NUM> to be used as a fulcrum, being engaged therewith.

The lamp body <NUM>, which has been accommodated in the housing part <NUM>, can be rocked in order to adjust the irradiation direction of the LED <NUM> with the use of the tip of the leg part <NUM>, being engaged with the receiving part <NUM>, as a fulcrum. Herein, although, with the lamp body <NUM>, the orientation of the opening part <NUM> can be changed in a variety of directions, such as the vertical, horizontal, and oblique ones, with the use of the tip of the leg part <NUM> as a turning center, however, in the present embodiment, the opening part <NUM> is guided within the guide opening 63a, being extended in a vertical direction. Therefore, the displacement of the lamp body <NUM> is restricted to rocking in a vertical direction with the tip of the leg part <NUM> being used as a turning center, whereby the irradiation direction of the LED <NUM> can be adjusted vertically.

As described above, in the inside of the housing part <NUM>, the outer periphery of the cover <NUM> of the lamp body <NUM> is slidably butted against the inner side of the front wall <NUM>, and in addition, the outer periphery of the entire lamp body <NUM> is surrounded by the outer periphery wall <NUM>, further, the tip of the leg part <NUM>, being protruded from the base <NUM> of the lamp body <NUM>, being engaged with the receiving part <NUM> of the back wall <NUM>. In this way, the lamp body <NUM> is supported between the front wall <NUM> and the back wall <NUM> of the bracket <NUM> so as to be displaceable with the tip of the leg part <NUM> being used as a fulcrum, the position thereof being held by the friction force, which is given in the supported state.

In addition, besides the opening part <NUM> of the lamp body <NUM> being guided within the guide opening 63a of the bracket <NUM>, the locating pin 24a in the base <NUM> is also guided by an elongated hole 66a, being provided for a later-described mounting part <NUM> (see <FIG>). However, the guidance of the locating pin 24a by the elongated hole 66a is not always needed, the locating pin 24a and the elongated hole 66a mainly playing a role as components allowing the top and bottom portions of the lamp body <NUM> to be easily identified.

The mounting parts <NUM> and <NUM> of the bracket <NUM> are to be fixed to the frame inside of the backrest <NUM>, being configured as components separate from the housing part <NUM> and retrofitted thereto. The mounting parts <NUM> and <NUM> are formed of a metallic material, being worked to a variety of sizes and shapes in accordance with the location and shape of the frame, to which they are mounted in the inside of the backrest <NUM>. The number of mounting parts <NUM> and <NUM> is not limited to two. As an ancillary structural element, rather than a separate part like the mounting parts <NUM> and <NUM>, an eaves part <NUM> is provided on the side of the front wall <NUM> in the housing part <NUM>. This eaves part <NUM> is a portion for concealing a gap that may be produced in the mounting place, depending upon the geometry of the surface of the backrest <NUM>, in which the reading lamp <NUM> is disposed.

Next, the optical characteristics of the lens for illumination <NUM> will be explained. As shown in <FIG>, with the present lens for illumination <NUM>, the lens body <NUM> distributes the light incident from the LED <NUM> in a predetermined direction or range. The light from the LED <NUM> is efficiently taken in into the inside of the lens body <NUM> from the incident face <NUM>, being provided in a recessed manner in the bottom apex part of the lens body <NUM>. Herein, the light from the LED <NUM> is advanced straight or bent to be passed through the inside of the lens body <NUM> in accordance with the angle with respect to the incident face <NUM>.

More specifically, the incident face <NUM> is comprised of a first incident face <NUM>, providing a bottom face of the recessed part, and a second incident face <NUM>, providing a side face of the recessed part, both incident faces being different from each other in the light distribution characteristics. Thereby, the light from the LED <NUM> can be efficiently utilized. The light incident from the first incident face <NUM> is advanced straight or bent so as to be passed through an internal region of the lens body <NUM> apart from the reflection face <NUM>, and emitted to the outside from the inner region <NUM> of the emission face <NUM>.

In addition, the light incident from the second incident face <NUM> is advanced straight or bent toward the predetermined range <NUM>, being closer to the bottom apex part, within the reflection face <NUM> in the lens body <NUM>. Then, the light, which has been totally reflected in the predetermined range <NUM> of the reflection face <NUM>, is condensed in a direction approximately in parallel with the optical axis L of the LED <NUM>, being emitted to the outside from the outer region <NUM> of the emission face <NUM>.

In this way, the second incident face <NUM> refracts the light from the LED <NUM> toward the reflection face <NUM>, however, it will not refract the light toward the entire area of the reflection face <NUM>, but will distribute the light only in the predetermined range <NUM>, which is closer to the bottom apex part. With such a method of light distribution control, even if the passenger obliquely views the emission face <NUM>, which closes the opening part <NUM>, even the predetermined range <NUM>, being located in the deeper area of the reflection face <NUM>, will not come into view, so long as the passenger does not intentionally peek deep into the lens body <NUM>. Therefore, within the total reflection face <NUM> of the lens body <NUM>, the upper portion <NUM> alone, from which the light will not be reflected, will normally enter the visual field, whereby uncomfortable glare can be suppressed.

By the way, as the irradiation range of the light that is to be provided by the reading lamp <NUM>, a quadrangle, corresponding to the shape of a magazine read by the seated person or the seat table, will be sufficient, however, with the conventional general reading lamp, light distribution in a circular shape, which includes a quadrangle, has been performed. With such light distribution in a circular shape, the distribution of light in the segment between the chord and the arc, which is produced on the outside of each side of a quadrangle inscribed in the circle, will be surplus.

Especially with the reading lamp <NUM>, which is applied to the seat <NUM> for use in a railroad vehicle, such surplus light distribution has presented a problem, such as it being directed toward the aisle on the lateral side of the seat <NUM> or the passenger on the front seat. Then, instead of using a method for obstructing the surplus light, by adapting the lens for illumination <NUM> itself to devise a lens for illumination 50A for modifying the irradiation range such that the light is originally distributed in a quadrangle, as described above, the light from the LED <NUM> can be efficiently utilized without wasting it.

More specifically, the outer periphery of the lens body 51A has four side faces <NUM>, which are inclined at an equal angle in four directions from the bottom apex part thereof. With such reflection face 520A, which is provided on the inner side of each side face <NUM>, the light, having reached from the second incident face <NUM> of the incident face <NUM>, can be condensed into a quadrangle (square), whereby the light distribution from the emission face <NUM> can be performed for a quadrangle (square).

Next, the characteristic action of the reading lamp <NUM> according to the present embodiment will be explained.

As shown in <FIG>, on the back side of the base <NUM> of the lamp body <NUM>, the leg part <NUM> is protruded, the tip of this leg part <NUM> being engaged with the receiving part <NUM> in the housing part <NUM>. The lamp body <NUM> can be rocked in the housing part <NUM> with the use of the tip of the leg part <NUM> as a fulcrum, whereby the irradiation direction of the LED 41can be adjusted. With such a lamp body <NUM>, the entire shape need not be a sphere as with the conventional technology.

As shown in <FIG>, for the base <NUM> of the lamp body <NUM>, the shape may be basically a disk-like simple one, allowing the LED <NUM> to be disposed on the front side thereof, with only the leg part <NUM> being locally protruded from the reference surface on the back side thereof. Accordingly, the shape of the lamp body <NUM> can be made non-bulky and compact, and the bracket <NUM>, supporting the lamp body <NUM>, can also be downsized. With the cover <NUM>, being assembled with the front side of the base <NUM>, the inside space of the lamp body <NUM> is secured.

As shown in <FIG>, the front wall <NUM> of the bracket <NUM> is formed such that the outer periphery of the cover <NUM> is slidably butted against the inner side thereof, whereby the cover <NUM>, which provides the front side of the lamp body <NUM>, can be positively held. In the apex part of the outer periphery of the cover <NUM>, the opening part <NUM> for irradiation is cylindrically protruded, being inserted into the guide opening 63a in the front wall <NUM>, whereby it can be rocked in a vertical direction.

In other words, the rocking of the lamp body <NUM> is restricted to that in a vertical direction, using the tip of the leg part <NUM> as a turning center, and thus the irradiation direction of the LED <NUM> can be adjusted only in a vertical direction. The opening part <NUM> of the lamp body <NUM> is protruded to the outside from the guide opening 63a of the front wall <NUM>, this opening part <NUM> serving as an operation part for moving the lamp body <NUM> by hand. Herein, the tip of the leg part <NUM>, which provides the inclination center of the base <NUM>, also provides the turning center of the optical axis of the LED <NUM> as it is, and thus adjustment of the irradiation direction of the LED <NUM> can be carried out while recognizing it with intuition.

In addition, the base <NUM> is integrally formed of a metal, also serving as a heat sink. Thereby, dissipation of the heat of the LED <NUM>, which is heated by luminescence, and the LED substrate <NUM> can be efficiently performed, whereby the temperature rise of the LED <NUM> and the LED substrate <NUM> can be suppressed. The LED <NUM>, which is disposed at the center of the front side of the base <NUM>, and the leg part <NUM>, which plays especially as a role of a heat dissipation fin on the back side of the base <NUM>, are matched with each other in location on the front and back sides of the base <NUM>, and yet around the leg part <NUM>, a plurality of ribs <NUM> are radially provided, whereby the heat dissipation can be further enhanced.

Next, assembling of the reading lamp <NUM> according to the present embodiment will be explained.

In order to assemble the lamp body <NUM>, which provides a critical part of the reading lamp <NUM>, the LED substrate <NUM> is first disposed on the mounting face <NUM> of the base <NUM> as shown in <FIG> and <FIG>. The mounting face <NUM> is provided with projections <NUM> as a locating means. By matching the projections <NUM> to the holes <NUM> in the LED substrate <NUM> such that they are fitted with each other, respectively, the LED <NUM> on the LED substrate <NUM> can be easily located. At this time, between the mounting face <NUM> of the base <NUM> and the LED substrate <NUM>, a packing <NUM> is interposed.

Next, above the mounting face <NUM> of the base <NUM>, the holder <NUM>, holding the lens for illumination <NUM>, is disposed on the LED substrate <NUM> in such a way that the former is superposed on the latter. Since the holder <NUM> is also provided with hole parts <NUM>, into which the respective projection <NUM> are to be fitted, the holder <NUM> and the lens for illumination <NUM> can also be easily located. At this time, there is no need for the holder <NUM> being bonded onto the LED substrate <NUM> or the lens for illumination <NUM> being bonded to the holder <NUM>.

Finally, the cover <NUM> is assembled to the base <NUM> in such a way that the latter is covered with the former from above the holder <NUM> of the lens for illumination <NUM>. Herein, the opening edge <NUM> of the cover <NUM> is matched to the outer periphery edge of the flange <NUM> of the base <NUM>, the engaging parts <NUM> on the cover <NUM> being snap-fit engaged with the engaged parts <NUM> on the base <NUM>, thereby they being fixed to each other. Therefore, in assembling the lamp body <NUM>, there is no need for using a fixing means such as an adhesive of a screw, and the assembly thereof can be made easily by simply utilizing the respective structures of the base <NUM> and the cover <NUM>.

Herein, how the above-mentioned snap-fit engaging is carried out will be explained in detail: as shown in <FIG>, with the engaging claw, which provides the engaging part <NUM> of the cover <NUM>, the claw tip thereof is expanded such that it gets on the outer periphery edge of the flange <NUM> of the base <NUM>, while being elastically deformed. Then, when the claw tip of the engaging part <NUM> has reached the engaged groove, which provides the engaged part <NUM>, the engaging claw is fitted into the engaged groove, while being returned to the original state, thus it completing the snap-fit engaging.

In this way, simply by making an operation of matching the cover <NUM> to the base <NUM> such that the former covers the latter, the snap-fit engaging will be completed in due course in association with such operation with no need for making an extra operation, such as separately deforming the engaging part <NUM> with the use of a tool, or the like. Yet, with the lens for illumination <NUM> in the holder <NUM>, the portion above the shoulder part <NUM> of the outer periphery thereof is fitted to the inner periphery of the opening part <NUM> of the cover <NUM>, with the top face of the shoulder part <NUM> being engaged with the stepped face of the shoulder part <NUM> of the inner periphery of the opening part <NUM>. In such a state, the lens body <NUM> is held between the holder <NUM> and the opening part <NUM>.

In the assembled lamp body <NUM>, not only the lens for illumination <NUM> and the holder <NUM>, but also the LED substrate <NUM> and the packing <NUM> are held in place, being engaged with each other. Thereby, simply by assembling the base <NUM> with the cover <NUM>, the component parts provided in the inside thereof can be fixed in the respective proper locations with a pressing force, being generated as a result of engaging with each other. In addition, the emission face <NUM> of the lens for illumination <NUM> is matched to the opening part <NUM> to block it, and thus there is no need for separately preparing such a part as a transparent protection cover to cover the opening part <NUM>.

The lamp body <NUM>, which has been thus assembled, is accommodated in the housing part <NUM> of the bracket <NUM> as described above for completion of a reading lamp <NUM>. In this way, the lamp body <NUM> is handled as one unit of the reading lamp <NUM>, together with the bracket <NUM>. Then, the reading lamp <NUM> is fixed to the frame in the backrest <NUM> of the seat <NUM> through the mounting parts <NUM> and <NUM> of the bracket <NUM> to thereby be offered to use by a seated person.

When the reading lamp <NUM> is to be used, the LED <NUM>, which is the light source, is turned on by means of a switch (not shown). Then, for adjusting the irradiation direction of the LED <NUM>, a finger is hooked on the opening part <NUM>, being protruded to the outside of the housing part <NUM>, to press it with an operating force exceeding the above-mentioned friction force, which holds the lamp body <NUM> in a stationary state. At this time, the lamp body <NUM> is rocked in a vertical direction with the tip of the leg part <NUM> of the base <NUM> being used as the turning center, and thus by leaving the hand from the opening part <NUM> at the point of time when it has been rocked to the desired irradiation direction, the lamp body <NUM> can be stopped in the relevant position.

Heretofore, the embodiment of the present invention has been described with reference to the drawings, however, the specific configuration is not limited to that of the embodiment as described above, and various changes and modifications may be included in the present invention, so long as they do not depart from the invention as defined in the appended claims. For example, for the lenses for illumination <NUM> and 50A, not only the entire geometry, but also the incident face <NUM>, the reflection faces <NUM> and 520A and the predetermined range <NUM> thereof, and the specific geometry and configuration of the emission face <NUM> are not limited to those shown, but can be altered as appropriate.

In addition, the lenses for illumination <NUM> and 50A can be utilized as an optical part for various lighting devices other than the reading lamp <NUM>. In addition, the seat <NUM>, being provided with a reading lamp <NUM>, including a lens for illumination <NUM> or 50A, is not limited to that for use in a railroad vehicle, and may be a seat to be installed in an airplane, a ship, or the like. In addition, instead of being directly provided in the seat <NUM>, the reading lamp <NUM> may be provided in such a place as the ceiling or the side wall such that it illuminates the seat <NUM>.

In addition, the specific geometry of a component constituting the reading lamp <NUM>, such as the lamp body <NUM> or the bracket <NUM>, is not limited to that illustrated. In addition, for the LED <NUM> and the substrate <NUM> thereof, being contained in the lamp body <NUM>, those which have various configurations other than illustrated may be adopted. In addition, the adjustability of the irradiation direction of the light source is not limited to the vertical direction, and may be adapted such that it is the horizontal direction or any specific angular direction as required.

Further, with the lamp body <NUM>, the cover <NUM> is provided with the engaging part <NUM>, while the base <NUM> being provided with the engaged part <NUM>, however, as an inverted aspect of the present embodiment, it may be configured such that the cover <NUM> is provided with the engaged part <NUM>, while the base <NUM> being provided with the engaging part <NUM>. Herein, the engaging part <NUM> is not limited to a claw-like one, and the engaged part <NUM> is not limited to a groove-like one into which the above-mentioned claw is fitted.

The lens for illumination of the present invention is widely applicable also to various illuminators other than the reading lamp as an optical part thereof.

Claim 1:
An illumination lens (<NUM>) for distributing light from a light source (<NUM>), comprising:
a lens body (<NUM>) including an incident face (<NUM>), a reflection face (<NUM>),and an emission face (<NUM>); and
a mounted part (<NUM>) for attaching the lens body (<NUM>) to a mating component, wherein
the incident face (<NUM>) is formed in a recessed shape at a bottom apex part of said lens body (<NUM>) to receive light from the light source (<NUM>);
the reflection face (<NUM>) is formed on an inner side of an outer periphery of said lens body (<NUM>), so as to totally reflect the light from said incident face (<NUM>);
the emission face (<NUM>) is formed at an upper end of said lens body (<NUM>) to emit light from said incident face (<NUM>) and said reflection face (<NUM>) to an outside of the lens body (<NUM>),
said mounted part is formed on the outer periphery of the lens body (<NUM>) at two-thirds of a whole height of the lens body (<NUM>) from the bottom apex part thereof, along a height direction of said reflection face (<NUM>),
said incident face (<NUM>) is configured to distribute light only to a predetermined range (<NUM>) of the reflection face (<NUM>), corresponding to a part of the reflection face (<NUM>) which ranges from the bottom of the apex part to two thirds of the overall height of the lens body (<NUM>), and said incident face (<NUM>) is configured not to distribute light to an upper portion (<NUM>) of the reflection face (<NUM>) adjacent to the emission face (<NUM>), said upper portion (<NUM>) including a location where the mounted part (<NUM>) is formed and a further portion of the reflection face (<NUM>) extending from the mounted part (<NUM>) to the emission face (<NUM>).