Abstract:
In a lighting device provided on a ceiling of an interior of a vehicle, the lighting device has: a map lamp including: a case; a first light guide plate accommodated in the case, and having a light incident area on an end face and a light radiation area on a flat plate surface of the interior side of the vehicle; a first light source part having a plurality of LED lamps, the LED lamps being opposed to the light incident area and arranged in an array; and a prism lens provided in the light radiation area side of the first light guide plate. The map lamp allows the light of the first light source part to be incident on the first light guide plate from the light incident area, radiates the light from the light radiation area to convert the light into a planar light, and then converts the light into a light advancing in a prescribed direction to light a prescribed area in the interior of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an improvement of a lighting device used in an interior of a vehicle. 
         [0003]    2. Description of the Related Art 
         [0004]    In a lighting device for an interior of a vehicle, since a map lamp for lighting a part near the hand of a person riding on the vehicle or a room lamp for lighting a wide area in the interior of the vehicle is provided in a restricted area such as a ceiling in the interior of the vehicle, the lamp needs to be compact and thin. For instance, patent literature 1 discloses a lighting device using an LED lamp as a light source of a map lamp. Further, patent literature 2 discloses a room lamp including an LED lamp and a light guide plate to convert the light of the LED lamp to a planar light by the light guide plate and light an interior of a vehicle. 
         [0005]    Patent literature 1: JP-A-2008-53065 
         [0006]    Patent literature 2: JP-A-2000-127847 
         [0007]    In the structure of the patent literature 1, since the LED lamp is a point light source and its directivity is higher than that of a bulb lamp, an area (glare) where a luminance is excessively high may occasionally generated to dazzle a person riding on the vehicle. Further, in the LED lamp that the light of an LED element is mixed with a fluorescence by a fluorescent material dispersed in a seal member to radiate the light of a prescribed color, the light of the LED element is not sufficiently mixed with the fluorescence so that a color shade or a color separation may arise. Further, when such a radiated light of the LED lamp is converged by a lens, the color shade or the color separation is more outstanding due to the aberration of the lens. Since the map lamp is used when the person riding on the vehicle looks at a map to light a spot on the map, such glare, color shade and color separation especially cause a problem. Further, when the lighting device is externally observed, the LED lamp is visually recognized, so that an outward appearance is not good. Further, since the structure of the patent literature 1 separately includes the light source of the map lamp and the light source of the room lamp, the number of parts is increased, an attaching operation is complicated and a cost is undesirable. As one of countermeasures for solving the problems, such a structure as in the patent literature 2, that is, the structure in which the LED lamp and the light guide plate are used to form the planar light may be supposed to be applied to the map lamp. However, since the light of the map lamp requires the directivity and the luminance higher than those of the light of the room lamp, when the light of the LED lamp as the point light source is simply converted into the planar light by the light guide plate, the directivity and the luminance necessary for the light of the map lamp cannot be obtained. Further, the structure of the patent literature 2 includes the map lamp and the room lamp integrally, however, since the directions of the lights irradiated therewith are different from each other, the light source parts thereof are separately provided. Therefore, controlling harnesses need to be managed by the light source parts respectively so that an attaching operation is complicated. Further, a labor for inspecting a product is increased. Further, since a heat radiating member needs to be separately provided as well as the harnesses, the number of parts is undesirably increased. 
       SUMMARY OF THE INVENTION 
       [0008]    Thus, it is an object of the present invention to provide a structure in which the generation of a glare, a color shade or a color separation is prevented in a lighting device including a map lamp using an LED lamp. Further, it is an object of the present invention to provide a structure that can obtain a sufficient quantity of light and luminance in a lighting device including a map lamp using an LED lamp. Further, it is an object of the present invention to provide a structure that has the small number of parts and is easy in an attaching operation. 
         [0009]    In order to achieve the object, according to a first aspect of the present invention, a lighting device provided on a ceiling of an interior of a vehicle comprises a map lamp including a case, a first light guide plate accommodated in the case, and having a first light incident area on an end face and a first light radiation area on a flat plate surface of the interior side of the vehicle, a first light source part having a plurality of LED lamps, the LED lamps being opposed to the first light incident area and arranged in an array; and a prism lens provided in the first light radiation area side, wherein the map lamp allows the light of the first light source part to be incident on the first light guide plate from the first light incident area, radiates the light from the first light radiation area to convert the light into a planar light, and then converts the light into a light advancing in a prescribed direction to light a prescribed area in the interior of the vehicle. 
         [0010]    In the lighting device of the present invention, the first light guide plate emits a planar light by the lights of the LED lamps to radiate the planar light. The planar light lights the prescribed area in the interior of the vehicle through the prism lens so that the lighting device functions as the map lamp. The lights of the LED lamps are guided or introduced to the light guide plate and mixed together to equalize a luminance. Further, since the luminance per unit area in a light-emitting surface is made to be lower than that of a usual point shaped light, the generation of glare is prevented. Further, when the lights are guided or introduced to the first light guide plate, since the lights are mixed together, the generation of a color shade or a color separation is prevented. Further, since the lights of the first light source are converted into the light advancing in the direction of the prescribed area by the prism lens, a sufficient quantity of light and luminance are obtained as the light of the map lamp in the area. Further, since the lights are temporarily converted into the planar light and sufficiently mixed together, and then, the planar light passes through the prism lens, the color separation due to the aberration of the lens hardly arise. As described above, according to the lighting device of the present invention, the LED lamps as the point light sources are used to emit the planar light in the light guide plate so that the lighting device may be preferably used as the map lamp. 
         [0011]    According to a second aspect of the present invention, a lighting device is provided, in addition to the structure according to a first aspect, which further has a room lamp including a second light guide plate provided integrally with the first light guide plate and having a second light incident area on an end face, a second light radiation area on a flat plate surface of the interior side of the vehicle and a connecting area connected to a side part of the first light guide plate on a side surface; and a second light source part having a plurality of LED lamps, the LED lamps being opposed to the second light incident area and arranged in an array; wherein the room lamp allows the light of the second light source part to be incident on the second light guide plate from the second light incident area and radiates the light from the second light radiation area to convert the light into a planar light to light the interior of the vehicle. The lighting device integrally includes the map lamp and the room lamp and the first light guide plate used for the map lamp and the second light guide plate used for the room lamp are integrally formed. Since both the map lamp and the room lamp are formed with the LED lamps and the light guide plates, an entire part of the device may be formed to be thinner than a case that a bulb lamp is used. Since the lighting device of the present invention is provided in a restricted area such as a ceiling of the vehicle, the thin lighting device is provided in such a way to improve a degree of freedom in design. 
         [0012]    According to a third aspect of the present invention, a lighting device is provided, in addition to the structure according to the second aspect, wherein the end face having the first light incident area of the first light guide plate and the end face having the second light incident area of the second light guide plate are located on the same virtual plane, and the first light source and the second light source are provided on the same base plate. Thus, the number of parts is reduced and an attaching workability is improved. Further, since the same base plate is used, harnesses do not need to be managed to control the first light source and the second light sources respectively. Thus, the number of parts is effectively reduced, the attaching workability is improved and a labor for inspecting a product is reduced. Further, heat radiating mechanisms doe not need to be separately provided in the first light source and the second light source respectively to make the device compact. 
         [0013]    According to a fourth aspect of the present invention, a light shield unit is provided in the connecting area in the structure according to the second aspect or the structure according to the third aspect. By the light shield unit, the movement of the light is prevented between the first light guide plate and the second light guide plate. Thus, the light guided or introduced to the first light guide plate is prevented from leaking to the second light guide plate and the light guided or introduced to the second light guide plate is prevented from leaking to the first light guide plate. As a result, when the device is externally observed during the emission of the light, an outward appearance is good. The light shield unit is not especially limited. A space part is provided or a member high in its reflection property, members having different refractive indexes or a member low in its light transmittance are provided, which may be adopted as the light shield unit. When the member high in its reflection property is provided among them, the light guided or introduced to the first light guide plate is prevented from leaking to the second light guide plate and the light is reflected toward the first light guide plate to make the light incident on the first light guide plate again. Thus, the utilization factor of the light is improved. 
         [0014]    According to a fifth aspect of the present invention, the light shield unit is a slit shaped through hole along the side surface of the first light guide plate in the structure according to the fourth aspect. By this through hole, the light guided or introduced to the first light guide plate is prevented from leaking to the second light guide plate and the light guided or introduced to the second light guide plate is prevented from leaking to the first light guide plate. Thus, when the device is externally observed during the emission of the light, an outward appearance is good. The form of the through hole is not especially limited, however, the through hole is preferably provided so as to extend along the side surfaces of the first light guide plate and the second light guide plate, because the leakage of the light is effectively prevented. 
         [0015]    According to a sixth aspect of the present invention, a lighting device is provided, in addition to the structure according to the fifth aspect, wherein the case includes a rib shaped protrusion fitted to the through hole in the connecting area of the first light guide plate and the second light guide plate. Thus, a light shield effect in the through hole part of the first light guide plate and the second light guide is improved and the first light guide plate and the second light guide plate are easily positioned by the rib shaped protrusion. When a slit shaped recessed part of a connecting part is provided from the interior side of the vehicle to the ceiling side, the rib shaped protrusion serves as a partition plate for partitioning a room lamp area and a map lamp area. Thus, the lighting device is externally observed, an outward appearance is preferable to improve design characteristics. 
         [0016]    According to a seventh aspect of the present invention, a lighting device is provided, in addition to the structure according to any one of the second to the sixth aspects, further comprising: a vessel that is provided in the interior side of the vehicle of the prism lens, sandwiches the first light guide plate, the second light guide plate and the prism lens between the case and the vessel and has a frame shaped protrusion for dividing a map lamp light emitting part corresponding to the first light radiation area and a room lamp light emitting part corresponding to the second light radiation area. The “frame shaped protrusion” mentioned herein forms a continuous wall surface with a prescribed height. In the present exemplary embodiment, the frame shaped protrusion forms the wall surface of the prescribed height continuously extending along a boundary part of the map lamp light emitting part and the room lamp light emitting part. Thus, the frame shaped protrusion serves as a partition plate for partitioning the room lamp area and the map lamp area so that the radiated light (the light of the map lamp light emitting part) that is radiated from the light radiation area of the first light guide plate is prevented from leaking to the room lamp light emitting part and the radiated light (the light of the room lamp light emitting part) that is radiated from the light radiation area of the second light guide plate is prevented form leaking to the map lamp light emitting part. Thus, the outward appearance is more preferable. Further, the frame shaped protrusion may be fitted to the through hole of the connecting area. Thus, the leakage of the light can be more prevented in the through hole of the connecting area. 
         [0017]    Now, an exemplary embodiment of the present invention will be described below by referring to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a view of a lighting device  1  seen from an interior side of a vehicle. 
           [0019]      FIG. 2  is an exploded perspective view of the lighting device  1 . 
           [0020]      FIG. 3A  is a top view of a light guide plate  60  and  FIG. 3(B)  is a sectional view taken along a line A-A of  FIG. 3(A) . 
           [0021]      FIG. 4  is a front view of a light source base plate  20 . 
           [0022]      FIG. 5  is a sectional view taken along a line B-B of the lighting device  1  shown in  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]      FIG. 1  shows a diagram of a lighting device  1  of an exemplary embodiment of the present invention seen from an interior side of a vehicle. An exploded perspective view of the lighting device  1  is shown in  FIG. 2 . The lighting device  1  is provided on a ceiling in the interior of a vehicle between a driver&#39;s seat and an assistant&#39;s seat. As shown in  FIG. 1 , the lighting device  1  roughly includes map lamp light emitting parts  2  provided at two right and left parts, a room lamp light emitting part  3  provided in a center, switch knobs  31  and a vessel  6 . More specifically, as shown in  FIG. 2 , the lighting device  1  includes, in order from the ceiling side of the vehicle, a control circuit board  10 , a case  1 , a light source base plate  20 , a switch housing  50 , the switch knobs  31  and  41 , a light guide plate  60 , an optical sheet  70 , a prism lens  8 , the vessel  6  and fixing clips  9 . The case  11  has a substantially flat plate form and includes recessed parts  12  at corner parts in the front side of the vehicle (an upper part of the sheet surface of  FIG. 1 ). The lighting device  1  is attached to the ceiling (not shown in the drawing) of the interior of the vehicle through the fixing clips  9  and an attaching protrusion  5  provided in a below-described vessel  6 . 
         [0024]    The light guide plate  60  is provided in the interior side of the vehicle in the case  11 .  FIG. 3(A)  shows a top view of the light guide plate  60 .  FIG. 3(B)  shows a sectional view taking along a line A-A in  FIG. 3(A) . As shown in  FIG. 3(A) , the light guide plate  60  includes two first light guide plates  61  and one second light guide plate  62 . The first light guide plates  61  and the second light guide plate  2  are made of a colorless and transparent acryl material. The first light guide plates  61  are arranged at both right and left sides of the second light guide plate  62  and the light guide plates are formed integrally through connection parts  63 . The first light guide plate  61  has a substantially flat plate form. The first light guide plate  61  has a thickness that is smaller from an end part  61   a  toward an opposite end part  61   b . The second light guide plate similarly has a substantially flat plate form and has a thickness that is smaller from an end part  62   a  toward an opposite end part  62   b . The connection part  63  includes connecting parts  64  and  65  and a slit part  66 . The connecting part  64  connects the end part  61   a  of the first light guide plate  61  to the end part  62   a  of the second light guide plate  62 . The connecting part  65  connects the end part  61   b  of the first light guide plate  61  to the end part  62   b  of the second light guide plate  62 . On the other hand, the slit part  66  is a through hole formed continuously in the form of a straight line from a part near the end part  61   a  to a part near the end part  61   b . The first light guide plate  61  is formed with a prescribed angle relative to the second light guide plate  62 . In the present exemplary embodiment, as shown in  FIG. 3(B) , an angle θ formed by the second light guide plate  62  and the first light guide plate  61  is about 20°. As described above, the first light guide plate  61  and the second light guide plate  62  are integrally formed. However, in areas excluding the parts near both the end parts  61   a  and  61   b , the through holes (the slit parts  66 ) are provided between the first light guide plates  61  and the second light guide plates. Thus, the first light guide plates  61  and the second light guide plate  62  are not substantially continuous. On the back surfaces (surfaces opposite to the interior of the vehicle) of the first light guide plates  61  and the second light guide plate  62 , a micro-lens machining process is applied as a light reflecting process. As the light reflecting process, a white color painting process may be used as well as a reflection lens machining process such as the micro-lens machining process. 
         [0025]    The light source base plate  20  is provided in the end part  61   a  side of the first light guide plate  61  and the end part  62   a  side of the second light guide plate  62 .  FIG. 4  shows a front view of the light source base plate  20 . On a mounting surface of the light source base plate  20 , eight first LED lamps  21  and eleven second LED lamps  22  are provided. The four first LED lamps  21  are arranged in the form of an array along the end part  61   a  of each of the first light guide plates  61 . The second LED lamps  22  are arranged in the form of an array along the end part  62   a  of the second light guide plate  62  in the longitudinal direction of the light source base plate  20 . The first LED lamp  21  is a white color LED lamp obtained by combining a yellow fluorescent material with a blue color LED chip. The second LED lamps  22  include six white color LED lamps obtained by combining the yellow fluorescent materials with the blue color chips and five amber color LED lamps. As the white color LED lamp, a white color LED lamp obtained by combining the yellow fluorescent material and a red fluorescent material with the blue color LED chip may be employed. The light source base plate  20  is electrically connected to the control circuit board  10 . The lighting states of the white color LED lamps and the amber color LED lamps are controlled through the control circuit board  10  so that the color temperatures of light emitting colors may be adjusted. In the present exemplary embodiment, the color temperature of the light emitting colors is adjusted to represent a lighting mode imitating a sunrise or a sunset. 
         [0026]    The optical sheet  70  is provided in the interior side of the vehicle of the light guide plate  60 . As shown in  FIG. 2 , the optical sheet  70  includes, in order from the light guide plate  60  side, a diffusing sheet  71 , a vertical prism sheet  72  and a horizontal prism sheet  73 . Further, the vertical prism sheet  72  is a sheet in which a polyester film layer having the form of the vertical prism is formed on the surface of a base material made of an acrylic resin. The horizontal prism sheet  73  is a sheet in which a polyester film layer having the form of the vertical prism is formed on the surface of a base material made of an acrylic resin. The forms of the sheets  71 ,  72  and  73  are substantially the same and respectively have substantially the same form in plan view as that of the surface of the light guide plate  60  in the interior side of the vehicle. The sheets respectively include opening parts having the same forms in plan view at positions corresponding to the slit parts  66  of the light guide plate  60 . The lights guided or introduced to the first light guide plate  61  or the second light plate  62  and outputted from the front surfaces of the light guide plates pass through the optical sheet  70 . Thus, the light flux thereof is adjusted to improve the luminance of the front surface. 
         [0027]    The prism lens  8  is located in the interior side of the vehicle of the optical sheet  70  and provided at a position opposed to the first light guide plate  61 . The prism lens  8  is provided in parallel with the first light guide plate  61 . The prism lens  8  is made of a colorless and transparent acrylic material and has a prescribed prism cut applied in the interior side of the vehicle to converge the lights radiated from the first light guide plate  61  to a prescribed direction (a direction of the hand of a person riding on the vehicle). 
         [0028]    The switch knobs  31  and  41  and the switch housing  50  are provided in the back part of the light source base plate  20 . The switch knobs  31  and  41  are tact switches (momentary switches) and connected to the control circuit board  10  to control the first LED lamps  21  to be turned on and off. The second LED lamps  22  are controlled to be turned on and off in cooperation with opening and closing operations of a vehicle door  8  (not shown in the drawing). 
         [0029]    The vessel  6  faces the interior side of the vehicle and sandwiches the light source base plate  20 , the switch housing  50 , the switch knobs  31  and  41  for the map lamp, the light guide plate  60 , the optical sheet  70  and the prism lens  8  between the case  11  and the vessel  6 . A central area of the vessel  6  is opened and covered with an outer lens  7 . In a rear side (an upper part of the sheet surface of  FIG. 1 ) of the vehicle of the vessel  6 , two attaching protrusions  5  are provided. Inside the vessel  6 , ribs  80  are provided upright.  FIG. 5  shows a sectional view taken along a line B-B in  FIG. 1 . As shown in  FIG. 5 , the ribs  80  are frame shaped protrusions forming wall surfaces continuously extending with a prescribed height along the connection parts  63  of the first light guide plates  61  and the second light guide plate  62  and divide the right and left areas (map lamp areas)  2  corresponding to the first light guide plates  61  from the central area (the room lamp light emitting area)  3 . The rib  80  includes a first rib  80   a  and a second rib  80   b  and has a sectional form of a V shape closing in the interior side of the vehicle. An upper end of the first rib  80   a  abuts on the prism lens  8  to support the prism lens  8 . On the other hand, an upper end of the second rib  80   b  abuts on the optical sheet  70  along the edge part of the second light guide plate  62 . 
         [0030]    As shown in  FIG. 5 , inside the case  11 , rib shaped protrusions  13  are provided along the side parts of the second light guide plate  62 . The rib shaped protrusions  13  are fitted to the slit parts  66  of the light guide plate  60 . Thus, the leakage of the light is prevented between the first light guide plates  61  and the second light guide plate  62 , and the first light guide plates  61  and the second light guide plate  62  are easily positioned. 
         [0031]    Now, a light emitting operation of the lighting device  1  will be described below. Initially, when the switch knobs  31  and  41  are pressed to turn on the first LED lamps  21 . The lights of the first LED lamps  21  are incident on the first light guide plate  61  from the first end part  61   a  of the first light guide plate  61  opposed to the first LED lamps  21  and guided or introduced to the first light guide plate  61 . The guided lights are reflected by the back surface of the first light guide plate  61  and radiated from the front surface (the interior side of the vehicle) to be changed to a planar light. The radiated planar light is diffused by the diffusing sheet  71  to equalize the luminance. Then, the light flux thereof is adjusted by the vertical prism sheet  72  and the horizontal prism sheet  73  to improve the luminance. Then, the planar light is converged to a part near the hand of the person riding on the vehicle in the form of a spot by the prism lens  8  to become the light of the map lamp. The light of the map lamp is a light resulting from the lights of the first LED lamps  21  as point light sources. When the lights of the first LED lamps are converted into the planar light through the first light guide plate  61 , a mixture of the lights is accelerated to equalize the luminance and prevent the generation of glare and a color shade. Further, since the planar light is formed by the light guide plate  60 , a color separation is hardly generated, Further, after the luminance of the front surface is improved by the optical sheet  70 , since the light is applied to a desired direction by the prism lens  8 , a sufficient quantity of light is obtained. 
         [0032]    On the other hand, when the vehicle door is opened, the second LED lamps  22  are turned on in cooperation therewith. The lights of the second LED lamps  22  are incident on the second light guide plate  62  from the end part  62   a  of the second light guide plate  62  and guided to the second light guide plate  62 . The guided lights are reflected by the back surface of the second light guide plate  62  and radiated from the front surface (the interior side of the vehicle) to be changed to a planar light. The radiated planar light is diffused by the diffusing sheet  71  to equalize the luminance. Then, in order to improve the luminance, the light flux thereof is adjusted by the vertical prism sheet  72  and the horizontal prism sheet  73 . Then, the planar light becomes the light of a room lamp for widely lighting the interior of the vehicle. 
         [0033]    As described above, the lighting device  1  serves as two kinds of lighting forms of the map lamp and the room lamp. In both the lamps, the lights of the LED lamps as the point light sources are converted into the planar light to be used. Here, the lighting device  1  is provided in the ceiling between the driver&#39;s seat and the assistant&#39;s seat. As shown in  FIG. 3(B) , the first light guide plate  61  of the map lamp light emitting part  2  is provided to be inclined to the second light guide plate  62  of the room lamp light emitting part  3  and faces the driver&#39;s seat side and the assistant&#39;s seat side. Thus, the interior of the vehicle may be widely lighted by the light of the room lamp light emitting part  3  and the part near the hand of the person riding on the vehicle may be preferably lighted by the light of the map lamp light emitting area  2 . Further, since the first light guide plates  61  and the second light guide plate  62  are integrally formed, the number of parts is reduced and an attaching workability is improved. 
         [0034]    The first light guide plates  61  and the second light guide  62  are integrally formed. However, the slit parts  66  are provided in the connection parts  63  of the first light guide plates  61  and the second light guide plate  62  to prevent the lights guided to the first light guide plates  61  from being incident on the second light guide plate  62  and prevent the lights guided to the second light guide plate  62  from being incident on the first light guide plates  61 . Thus, an outward appearance is preferable when the lamps are turned on. Further, the rib shaped protrusions  13  of the case  11  are fitted to the slit parts  66 . Thus, the lights guided or introduced to the first light guide plates  61  are more prevented from being incident on the second light guide plate  62  and the lights guided or introduced to the second light guide plate  62  are more prevented from being incident on the first light guide plates  61 . Thus, the outward appearance is more preferable when the lamps are turned on. Further, by the ribs  80  of the vessel  6 , the lights radiated form the first light guide plates  61  are prevented from being observed from the room lamp light emitting part  3 , and the lights radiated from the second light guide plate  62  are prevented from being observed from the map lamp light emitting part  2 . Thus, the outward appearance is more improved when the lamps are turned on. In the present exemplary embodiment, the rib shaped protrusions  13  of the case  11  are fitted to the slit parts  66 , however, in place thereof, a part of the ribs  80  of the vessel  6  may be fitted to the slit parts  66 . The same effect is also achieved thereby. 
         [0035]    In the present invention, since the first LED lamps  21  and the second LED lamps  22  are used as a light source, the lighting device is formed to be thinner than a case that a bulb type lamp is used. Further, in the light guide plate  60 , the right and left first light guide plates  61  are inclined at a prescribed angle θ relative to the second light guide plate  62 , a space part P (see  FIG. 5 ) is formed in the ceiling side of the vehicle, devices (not shown in the drawing) mounted on the control circuit board  10  are respectively accommodated in the space part P, so that the lighting device is made to be thinner. Further, since the first LED lamps  21  and the second LED lamps  22  are provided on the same base plate, harnesses do not need to be managed, the number of parts is effectively reduced, an attaching workability is improved and a labor for inspecting a product is reduced. 
         [0036]    The present invention is used as the lighting device of the interior of the vehicle. 
         [0037]    The present invention is not limited to above-described embodiment and the explanation of the embodiment. The present invention includes various kinds of modified forms within a scope that may be easily thought of by a person with ordinary skill in the art without departing the description of claims. The contents of theses, Japanese Patent laid-open publications and Japanese Patent publications stated in this specification are all referred to as quotations.