Patent Publication Number: US-9406468-B2

Title: Relay

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority from Japanese Patent Application No. 2013-146260, filed on 12 Jul. 2013, the entire contents of which is incorporated herein by reference for all purposes. 
     FIELD 
     The present invention relates to a relay, specifically to a relay having a function of displaying planar emitting operation. 
     BACKGROUND 
     In a conventional relay, sometimes a pilot lamp is provided in order for a worker to easily check operation of a relay. The pilot lamp is provided in an upper portion of a housing of the relay so that the worker can easily visually recognize a lighting state of the pilot lamp. 
       FIGS. 1A and 1B  are schematic sectional view and a schematic plan view of a conventional relay  11  incorporating a pilot lamp therein. In relay  11 , a relay body  13  including a coil unit and a contact unit is assembled on a top surface of base  12 , and relay body  13  is covered with a transparent housing  14  attached onto base  12 . A Pilot lamp  15  constructed with an LED is provided in an upper portion of transparent housing  14 . Pilot lamp  15  is lit when relay  11  is in an on state, pilot lamp  15  is turned off when relay  11  is in an off state, and an operating state of relay  11  can be checked by lighting on or turning off pilot lamp  15 . 
     Because there is a need for downsizing of the relay, there is little room to allocate a sufficient space to provide pilot lamp  15  in transparent housing  14 , thus pilot lamp  15  is arranged in a gap between relay body  13  and transparent housing  14  and an optical axis of pilot lamp  15  is horizontally oriented. Therefore, in relay  11 , as indicated by a broken-line arrow in  FIGS. 1A and 1B , the light emitted from pilot lamp  15  is inevitably interrupted in a certain direction by a member (holder  18 ) holding relay body  13  (for example, spring  16  and cable  17  of the relay body) or pilot lamp  15  in transparent housing  14 . Accordingly, even if pilot lamp  15  is lit, the light emitted from pilot lamp  15  is hardly seen depending on the direction in which relay  11  is viewed, and sometimes the operating state of relay  11  cannot be checked. As illustrated in  FIG. 1A , because the light emitted from pilot lamp  15  hardly passes through a corner portion of transparent housing  14 , the light emitted from pilot lamp  15  can be hardly seen from this direction (oblique direction). 
     In the case that a plurality of relays  11  in  FIGS. 1A and 1B  are arrayed as illustrated in  FIG. 2 , for example, a light emission point (pilot lamp  15 ) of a right side relay  11  may be interrupted by transparent housing  14  of a relay  11  located on the left side of  FIG. 2 . Therefore, the light emitted from pilot lamp  15  is hardly recognizable from all directions. 
     Despite that pilot lamp  15  is a point light emission in relay  11  of  FIG. 1 , which makes the relay appear bright, the relay  11  will still be difficult to identify from another relay in the case when a plurality of relays is arrayed adjacent to each other. In particular, when the light emitted from pilot lamps  15  of one of the relays  11  is seen when it is transmitted through transparent housing  14  of the other relay  11 , it will be hard to distinguish which relay is brightened. Additionally, because pilot lamp  15  is the point light emission, when disturbance light is reflected by the top surface of the relay, the light emitted from pilot lamp  15  is hardly seen when the disturbance light overlaps the light emitted from pilot lamp  15 . 
       FIG. 3  is a perspective view of a relay  21  disclosed in Japanese Unexamined Patent Publication No. 2006-172731. In relay  21 , a portion in which the relay body (not illustrated) is provided above base  22  is covered with cover  23 . Rod-shaped light guide  24  extending in a vertical direction is provided in a side surface of cover  23 , and the pilot lamp (not illustrated) is arranged inside cover  23  and opposite to an inclined surface on a bottom surface of light guide  24 . The inclined surface on the bottom surface of light guide  24  constitutes reflecting surface  25 . When the light emitted from the pilot lamp is incident to light guide  24  from a substantially horizontal direction, the light is reflected by reflecting surface  25  to bend an optical path upward, the light travels upward in light guide  24  is then output to outside the cover  23  from the top surface of light guide  24 , known as a display surface  26 . As a result, display surface  26  located in the top surface of relay  21  looks bright, and the operating state of relay  21  can be visually recognized. 
     In relay  21 , because the top surface of relay  21  is brightened by guiding the light emitted from the pilot lamp using light guide  24  projected from the side surface, a point on an end of the top surface of relay  21  will appear bright. However, visibility is degraded when viewed from a side of a side surface opposite to the side surface through which light guide  24  allows light to pass, thus good visibility cannot be obtained when viewed from all directions. 
     In the case that a plurality of relays  21  are arrayed, when the top surface of a relay  21  is brightened, the light emission point is more visible behind an adjacent relay  21  compared with the relay  11  in  FIG. 1 . However, sometimes which relay is brightened is hard to recognize as it depends on the arrangement of the relays. For example, in the case that the relays are arrayed such that the side surfaces of the relays are opposite to each other, the light guide will be located between the relays adjacent to each other. Therefore, display surface  26  will look bright between the relays adjacent to each other, and which relay is brightened will be hard to distinguish from the other relays. 
     Because only a point of the end of the top surface of relay  21  appears bright, the light emission of relay  21  will be hard to see due to interruption of disturbance light caused by light reflection near the light emission point. 
     SUMMARY 
     In accordance with one aspect of an embodiment of the present invention, there is provided a relay in which a relay body and a light source are incorporated in a case, the light source emitting light in conjunction with operation of the relay body, wherein a light guide is provided inside an outer surface of the case, the light guide is configured to take in the light emitted from the light source, to guide the light to a portion parallel to a top panel of the case, and to spread the light in the portion parallel to the top panel, and an optical pattern is provided in at least one of a top surface and a bottom surface of the portion parallel to the top panel, the optical pattern is configured to output, the light guided in the light guide to the portion parallel to the top panel, to outside the case from a top surface of the top panel. 
     In accordance with another aspect of an embodiment of the present invention, there is provided a relay in which a relay body and a light source are incorporated in a case, the light source emitting light in conjunction with operation of the relay body, wherein an optical pattern is arranged below a top surface of a top panel of the case, the optical pattern is configured to refract the light incident from a bottom surface side and to output the light to outside the case from the top surface of the top panel, and the light source is arranged below the optical pattern such that an optical axis of the light source is oriented toward a horizontal direction or a direction looking up to the top panel from the horizontal direction within a spread angle of the light source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are schematic sectional view and a schematic plan view of a conventional relay incorporating a pilot lamp therein; 
         FIG. 2  is a schematic view illustrating a state in which light from one of a plurality of relays is interrupted by another relay when two of the relay in  FIG. 1  are arrayed; 
         FIG. 3  is a perspective view of a relay disclosed in Japanese Unexamined Patent Publication No. 2006-172731; 
         FIG. 4  is a partially exploded perspective view illustrating a relay according to a first embodiment of the present invention; 
         FIG. 5  is a sectional view of the relay in  FIG. 4 ; 
         FIG. 6A  is a perspective view illustrating an optical pattern provided on an inner surface of a housing of the relay, and  FIG. 6B  is a view of a top surface of the housing of the relay viewed from an oblique direction; 
         FIG. 7  is a schematic sectional view illustrating action of the relay in  FIG. 4 ; 
         FIG. 8  is a schematic sectional view illustrating a state in which two relays of the first embodiment are arrayed; 
         FIG. 9  is a schematic sectional view illustrating a relay according to a first modification of the first embodiment; 
         FIG. 10  is a schematic sectional view illustrating a relay according to a second modification of the first embodiment; 
         FIG. 11  is a schematic sectional view illustrating a relay according to a third modification of the first embodiment; 
         FIG. 12  is a schematic sectional view illustrating a relay according to a fourth modification of the first embodiment; 
         FIG. 13  is a schematic sectional view illustrating a relay according to a fifth modification of the first embodiment; 
         FIG. 14  is a schematic sectional view illustrating a relay according to a sixth modification of the first embodiment; 
         FIG. 15  is a schematic sectional view illustrating a relay according to a second embodiment of the present invention; 
         FIG. 16A  is a schematic view illustrating a state in which the relay of the second embodiment is viewed from directly above, and  FIG. 16B  is a schematic view illustrating a state in which the relay of the second embodiment is viewed obliquely from above; 
         FIG. 17  is a schematic sectional view illustrating a relay according to a third embodiment of the present invention; 
         FIG. 18  is a schematic sectional view illustrating a relay according to a fourth embodiment of the present invention; 
         FIG. 19  is a schematic sectional view illustrating a relay according to a first modification of the fourth embodiment; 
         FIG. 20  is a schematic sectional view illustrating a relay according to a second modification of the fourth embodiment; 
         FIG. 21  is a schematic sectional view illustrating a relay according to a third modification of the fourth embodiment; 
         FIG. 22  is a schematic sectional view illustrating a part of a relay according to a fifth embodiment of the present invention; 
         FIG. 23A  is a schematic view illustrating a partial section and a light intensity distribution of a relay according to a first modification of the fifth embodiment, and  FIG. 23B  is a schematic view illustrating a state and the light intensity distribution of the relay of the first modification in  FIG. 23A  when a pilot lamp is displaced; 
         FIG. 24A  is a schematic view illustrating a partial section and a light intensity distribution of a relay according to a second modification of the fifth embodiment, and  FIG. 24B  is a schematic view illustrating a state and the light intensity distribution of the relay of the second modification in  FIG. 24A  when the pilot lamp is displaced; 
         FIG. 25  is a schematic sectional view illustrating a part of a relay according to a sixth embodiment of the present invention; 
         FIG. 26  is a schematic view illustrating a partial section of a relay according to a first modification of the sixth embodiment; 
         FIG. 27  is a schematic view illustrating a partial section of a relay according to a second modification of the sixth embodiment; and 
         FIG. 28  is a sectional view illustrating an optical pattern having a different shape. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, but various design changes can be made without departing from the scope of the present invention. 
     First Embodiment 
     A relay according to a first embodiment of the present invention will be described below with reference to  FIGS. 4 to 8 .  FIG. 4  is a partially exploded perspective view illustrating relay  31  of the first embodiment.  FIG. 5  is a sectional view of relay  31 .  FIG. 6A  is a perspective view illustrating an optical pattern provided on an inner surface of housing  34   b  of relay  31 , and  FIG. 6B  is a view (photograph) of a top surface of housing  34   b  of relay  31  viewed from an oblique direction.  FIGS. 7 and 8  illustrate relay  31  in action. 
     Relay  31  incorporates relay body  32  and pilot lamp  33  in a case  34 . Case  34  includes base  34   a  made of an opaque resin and housing  34   b  made of a transparent resin. 
     Relay body  32  having a structure in  FIGS. 4 and 5  is provided on the top surface of base  34   a . Coil unit  41  is fixed to the top surface of base  34   a . A lower portion of armature  42  is opposite to an end surface of an iron core of coil unit  41 , and an upper portion of armature  42  is swingably supported by yoke  43 . One end of spring  44  (tension spring) is hooked in spring hook  45  provided on the top surface of yoke  43 , and the other end of spring  44  is hooked at an upper end of armature  42 . Accordingly, armature  42  is swingable back and forth, and the lower portion of armature  42  is inclined to move backwards when coil unit  41  is excited. Because a portion higher than a supporting point of armature  42  is elastically pulled backwards by spring  44 , the lower portion of armature  42  separates from the iron core to move forward when coil unit  41  is demagnetized. 
     A plurality of movable contact springs  46  are attached to a front surface of armature  42  by support  47  and are arranged in parallel to one another. A plurality of common terminals  49 , a plurality of normally-closed terminals  50 , and a plurality of normally-opened terminals  52  are inserted in base  34   a  so as to slot vertically into base  34   a . An upper end of the movable contact spring  46  is electrically connected to each common terminal  49  by cable  54 . A lower end portion of movable contact spring  46  is located between upper end portions of normally-closed terminal  50  and normally-opened terminal  52 , and movable contacts  48  are provided on both surfaces of the lower end portion of movable contact spring  46 , respectively. In front of movable contact  48 , normally-closed contact  51  is provided in the upper end portion of each normally-closed terminal  50  so as to be opposite to movable contact  48 . At the back of movable contact  48 , normally-opened contact  53  is provided in the upper end portion of each normally-opened terminal  52  so as to be opposite to movable contact  48 . 
     When coil unit  41  is not excited in relay body  32 , because the lower portion of armature  42  is moved forward after separating from the iron core, the lower portion of movable contact spring  46  also moves forward. Therefore, movable contact  48  is in contact with normally-closed contact  51  to close a circuit between common terminal  49  and normally-closed terminal  50 , and movable contact  48  separates from normally-opened contact  53  to open a circuit between common terminal  49  and normally-opened terminal  52 . 
     When coil unit  41  is excited, the lower portion of armature  42  is attracted by the iron core to move backwards, and the lower portion of movable contact spring  46  also moves backwards. Therefore, movable contact  48  comes into contact with normally-opened contact  53  to close the circuit between common terminal  49  and normally-opened terminal  52 , and movable contact  48  separates from normally-closed contact  51  to open the circuit between common terminal  49  and normally-closed terminal  50 . 
     Pilot lamp  33  is held by holder  35  and fitted in recess  35   a  provided in an end portion of holder  35 . Holder  35  is fixed to the upper surface of yoke  43 . Therefore, pilot lamp  33  is located in the upper end portion of a space in case  34 . Pilot lamp  33  is connected to a wiring portion (not illustrated). Pilot lamp  33  is lit or turned off according to an operating state of relay  31 , which enables a worker to visually recognize the operating state of relay  31 . For example, pilot lamp  33  is turned off during a non-operating state of relay  31 , namely, when the circuit between common terminal  49  and normally-opened terminal  52  is opened and the circuit between common terminal  49  and normally-closed terminal  50  is closed. On the other hand, pilot lamp  33  is lit during the operating state of relay  31 , namely, when the circuit between common terminal  49  and normally-opened terminal  52  is closed and the circuit between common terminal  49  and normally-closed terminal  50  is opened. 
     Housing  34   b  is a molded article made of a transparent resin, such as a polycarbonate resin, which has a high refractive index. Alternatively, housing  34   b  may be a molded article made of a translucent resin or a colored transparent resin. In such cases, desirably the translucent resin having high transparency and the colored transparent resin having a light color are used such that inside of relay  31  can be checked. 
     Light source arrangement part  38  in which a bottom surface is recessed upwards is provided in a corner portion of top panel  40   a  of housing  34   b . Pilot lamp  33  resides within light source arrangement part  38  when base  34   a  is attached to housing  34   b  to accommodate relay body  32  and pilot lamp  33  in case  34 . Pilot lamp  33  is accommodated in the recess of light source arrangement part  38  such that an optical axis of pilot lamp  33  is substantially oriented towards a horizontal direction. When pilot lamp  33  is viewed from a direction perpendicular to top panel  40   a , pilot lamp  33  is installed such that the optical axis of pilot lamp  33  is oriented towards optical pattern region  36  (in the example of the drawings, the optical axis of pilot lamp  33  is substantially oriented towards a diagonal direction of top panel  40   a ). In sidewall surfaces of light source arrangement part  38 , a wall surface located in a light emitting direction (optical axis direction) of pilot lamp  33  constitutes light incident surface  39  through which light is incident to inside of top panel  40   a.    
     As illustrated in  FIGS. 6A and 6B , in front of pilot lamp  33 , optical pattern region  36  is formed in a part of the bottom surface of top panel  40   a . In optical pattern region  36 , as illustrated in  FIG. 6A , many prism-shaped optical patterns  37  are formed into arc shapes around a place (a corner of optical pattern region  36 ) where the light is incident to optical pattern region  36  (or around the position of pilot lamp  33 , hereinafter the same holds true). In the example of  FIG. 6A , prism-shaped optical pattern  37  having a triangular shape in cross-section extends into a substantially arc shape around the light incident place, and optical patterns  37  are concentrically arranged. Alternatively, pyramid-like optical patterns  37  may concentrically be arranged around pilot lamp  33 . 
     As illustrated in  FIG. 5 , optical pattern  37  may be projected from the bottom surface of top panel  40   a , or optical pattern  37  having a triangular prism shape may be recessed in the bottom surface of top panel  40   a  like a first modification in  FIG. 9 . 
     Optical pattern region  36  can be formed on the top surface of top panel  40   a . However, when optical pattern region  36  is provided on the top surface of top panel  40   a , dust and dirt may accumulate in optical pattern region  36  and be hard to remove. Therefore, preferably optical pattern region  36  is provided in a bottom surface of top panel  40   a.    
     In relay  31 , sometimes the state of relay body  32  is checked through top panel  40   a  of housing  34   b . For this purpose, optical pattern region  36  is not provided on the whole surface of top panel  40   a  but is preferably formed in a manner to leave a region (transparent operation check window) for checking the inside of optical pattern region  36 . On the other hand, in order to perform planar emission at the top panel  40   a  to enable recognition of light from all directions, preferably optical pattern region  36  is made with an area of at least ⅕ times as large as that of top panel  40   a.    
     As illustrated in  FIG. 7 , when pilot lamp  33  of relay  31  is lit, the light emitted from pilot lamp  33  is incident to top panel  40   a  from light incident surface  39 , and the light is guided while reflected (total reflection) by the top and bottom surfaces of the top panel  40   a , which is part of the light guide, and spread in a planar state in top panel  40   a . With regard to the light guided in top panel  40   a  to reach optical pattern region  36 , the light that is reflected by optical pattern  37  and oriented upwards is output to outside the housing  34   b  (case) from the top surface of top panel  40   a . Accordingly, the light is output from the entire optical pattern region  36 , and the optical pattern region  36  of the top panel  40   a  emits the light in the planar state. 
     In relay  31 , the light emitted from pilot lamp  33  is guided in top panel  40   a , and the top surface of top panel  40   a  emits the light in the planar state in optical pattern region  36 . Therefore, the light is not interrupted by structures (such as cable  54 , spring  44 , and holder  35 ) in relay  31  or the corner portion of housing  34   b , thereby allowing the light of pilot lamp  33  to be recognized from all directions. Additionally, the top surface of relay  31  emits widely the light in the planar state, so that the lighting state of relay  31  can be visually recognized without the interruption of disturbance light even if the disturbance light is reflected by the top surface of relay  31 . 
     As illustrated in  FIG. 8 , even if a plurality of relays  31  are arrayed, the top surface of relay  31  emits the light in the planar state. Therefore, the light is not interrupted by adjacent relay  31 , but the light of relay  31  can be recognized from all directions. Additionally, when the top surface of relay  31  emits the light in the planar state, a wide area will be brightened. Therefore, which relay  31  is brightened is easily distinguished even if the plurality of relays  31  are arrayed adjacent to each other. 
     In relay  31 , even if pilot lamp  33  is horizontally installed and pilot lamp  33  has a certain extent of wide directional characteristic, the light is still emitted upwards from pilot lamp  33  through light source arrangement part  38 . As illustrated in  FIG. 7 , in order to efficiently use the light, when diffusion optical system  55  adheres to the top surface of top panel  40   a  above light source arrangement part  38 , or when diffusion optical system  55  is processed in the top surface of top panel  40   a  to diffuse the light transmitted through light source arrangement part  38 , a light emission area can be widened and visibility can be enhanced. Examples of diffusion optical systems  55  include a spherical projection having a relatively small curvature and a transparent sheet in which many projections having thin convex lens shapes are provided. 
     As illustrated in  FIG. 7 , in optical pattern region  36 , diffusion optical system  56  may be provided on the top surface of top panel  40   a . Diffusion optical system  56  may be processed on the top surface of top panel  40   a , overlapping and in close contact with the top surface of top panel  40   a , or provided on the top surface of top panel  40   a  with an air layer interposed therebetween. When diffusion optical system  56  is provided in optical pattern region  36 , the directional characteristic of the light output from optical pattern region  36  is widened to further enhance the visibility from all directions. 
     Modifications of First Embodiment 
     In the first modification of the first embodiment, as described above, optical pattern  37  may be recessed in the bottom surface of top panel  40   a . Various modifications can be made in addition to the first modification. 
       FIG. 10  is a schematic sectional view illustrating a relay according to a second modification of the first embodiment. In the second modification of the first embodiment, instead of providing light source arrangement part  38 , a protrusion having a light incident surface, namely, light introducing prism  57  is provided at a position opposite to pilot lamp  33 . The light emitted obliquely upwards from pilot lamp  33  is taken in top panel  40   a  from an inclined surface (light incident surface  39 ) of light introducing prism  57 , spreads in the planar state in top panel  40   a , and is reflected by optical pattern  37 , whereby the light is output upwards. 
       FIG. 11  is a schematic sectional view illustrating a relay according to a third modification of the first embodiment. In the third modification of the first embodiment, pilot lamp  33  is arranged such that an optical axis of pilot lamp  33  is oriented upwards. Horizontal light incident surface  39  is provided above pilot lamp  33 , and inclined reflecting surface  58  is provided in the top surface of top panel  40   a  and opposite to light incident surface  39 . The light emitted upwards from pilot lamp  33  is incident to top panel  40   a  from light incident surface  39 , and is totally reflected by reflecting surface  58 , whereby an optical path of the light is bent into a direction substantially parallel to top panel  40   a . The light guided in top panel  40   a  spreads in the planar state in top panel  40   a , and is reflected by optical pattern  37 , whereby the light is output upwards. In reflecting surface  58 , preferably diffusion optical system  55  is provided in a region where the light of pilot lamp  33  is not totally reflected but transmitted. 
       FIG. 12  is a schematic sectional view illustrating a relay according to a fourth modification of the first embodiment. In the fourth modification of the first embodiment, pilot lamp  33  is arranged such that the optical axis of pilot lamp  33  is oriented towards the horizontal direction and such that pilot lamp  33  is opposite to sidewall plate  40   b  of housing  34   b . In an inner surface of sidewall plate  40   b , a place opposite to pilot lamp  33  constitutes light incident surface  39 . In an outer surface of sidewall plate  40   b , reflecting surface  59  (first reflecting surface) inclined with respect to a surface perpendicular to a thickness direction of sidewall plate  40   b  is provided in a place opposite to light incident surface  39 . In outer surface of housing  34   b , inclined reflecting surface  60  (second reflecting surface) is provided in a corner portion located above reflecting surface  59 . Reflecting surfaces  59  and  60  may be made of a material totally reflecting the light, or formed by bonding a reflecting tape or by applying a reflecting paint. 
     In the fourth modification of the first embodiment, top panel  40   a  and sidewall plate  40   b  of housing  34   b  in  FIG. 12  constitute the light guide. That is, the light emitted in the horizontal direction from pilot lamp  33  is incident to sidewall plate  40   b  from light incident surface  39 , and is reflected by reflecting surface  59 , whereby the optical path of the light is bent upwards. The light reflected by reflecting surface  59  is incident to reflecting surface  60  through sidewall plate  40   b , is reflected by reflecting surface  60 , and is guided in the direction parallel to top panel  40   a . The light guided through the top panel  40   a  spreads in the planar state in top panel  40   a , and is reflected by optical pattern  37 , whereby the light is output upwards. 
     As illustrated in  FIGS. 10 to 12 , a sectional shape of optical pattern  37  may gradually be changed with distance from pilot lamp  33 . Because a quantity of light reaching optical pattern  37  decreases with distance from pilot lamp  33 , desirably optical pattern  37  located farther away from pilot lamp  33  is formed into a shape having higher light output efficiency of the output of the light from top panel  40   a  in order to obtain uniform luminance in optical pattern region  36 . 
       FIG. 13  is a schematic sectional view illustrating a relay according to a fifth modification of the first embodiment. In the fifth modification of the first embodiment, recess  40   c  having a substantially V-shape in section is provided in the top surface of top panel  40   a . Recess  40   c  is formed into an arc shape around the position of pilot lamp  33  when viewed from the direction perpendicular to the top surface of top panel  40   a . The place surrounded by recess  40   c  constitutes light source arrangement part  38 , and pilot lamp  33  is accommodated in the recess formed in the bottom surface of light source arrangement part  38 . In recess  40   c , the place opposite to pilot lamp  33  constitutes light incident surface  39 , and inclined surfaces  39   a  and  39   b  extend toward optical pattern region  36  from light incident surface  39 . In the example of  FIG. 13 , two inclined surfaces  39   a  and  39   b  have different inclined angles. Alternatively, the inclined angle of the inclined surface may be kept constant, or curved. 
     In the fifth modification of the first embodiment, recess  40   c  is formed by downwardly recessing a part of top panel  40   a , thereby forming light incident surface  39 . The light of pilot lamp  33  incident to top panel  40   a  from light incident surface  39  is guided through inclined surfaces  39   a  and  39   b  to reach optical pattern region  36 , and the light is output upward from optical pattern region  36 . 
     In the fifth modification of the first embodiment, as illustrated in  FIG. 14 , the optical axis of pilot lamp  33  may be inclined towards the direction close to an inclination of the inclined surface. Preferably the optical axis of pilot lamp  33  is inclined in a range greater than 0° and less than or equal to 30°. 
     Second Embodiment 
       FIG. 15  is a schematic sectional view illustrating relay  61  according to a second embodiment of the present invention. In relay  61 , a plurality of types of optical patterns is provided in optical pattern region  36 . Two types of optical patterns  37  and  62  are provided in the example of  FIG. 16 . Optical pattern  37  of the second embodiment is identical to that of the first embodiment, and the light guided through top panel  40   a  is reflected upwards. Optical pattern  62  reflects the light guided through top panel  40   a  towards an obliquely horizontal direction, namely, a direction having a small angle with respect to a horizontal surface. For example, optical pattern  37  and optical pattern  62  are formed into triangular prisms or pyramid-like prisms. Optical pattern  37  and optical pattern  62  differ from each other in the inclined angle of the inclined surface. Because other configurations of the second embodiment are similar to those of the first embodiment, the identical component is designated by the identical numeral, and the description is omitted (the same holds true from a third embodiment). 
     When relay  61  is viewed from above while pilot lamp  33  is lit, the light reflected by optical pattern  37  appears brightly. Therefore, when optical patterns  37  are substantially uniformly distributed in the entire optical pattern region  36 , the entire optical pattern region  36  will appear bright as illustrated in  FIG. 16A . On the other hand, the light reflected by optical pattern  62  is seen when relay  61  is viewed from an oblique direction. For example, when optical patterns  62  are arranged in the order of “ABC” in optical pattern region  36 , characters of “ABC” viewed from the oblique direction will appear brightly as illustrated in  FIG. 16B . Therefore, information, such as the character, a numerical character, and a mark, which is previously formed by optical pattern  62 , can be visually recognized during the lighting of pilot lamp  33  only when viewed from the specific direction. 
     Third Embodiment 
       FIG. 17  is a schematic sectional view illustrating relay  71  according to a third embodiment of the present invention. In relay  71 , light guide plate  72  constituting the light guide is arranged immediately below top panel  40   a  of housing  34   b . The corner portion of light guide plate  72  is cut to form light incident surface  73 . Pilot lamp  33  is arranged at the position opposite to light incident surface  73 . In the bottom surface of light guide plate  72 , many prism-shaped optical patterns  37  are formed into the arc shape around the place where the light is incident to optical pattern region  36  (see  FIG. 6A ). 
     In relay  71 , the light emitted from pilot lamp  33  is incident to light guide plate  72  from light incident surface  73 , and the light spreads in light guide plate  72  upon being reflected by the top surface and the bottom surface of light guide plate  72 . When the light propagating in light guide plate  72  is incident to optical pattern  37 , the light incident to optical pattern  37  is reflected towards the direction perpendicular to the top surface of light guide plate  72 . The light is emitted from the top surface of light guide plate  72 , and is transmitted through top panel  40   a  to light up the region opposite to light guide plate  72  with respect to top panel  40   a.    
     In the third embodiment, desirably light guide plate  72  has the area of at least ⅕ times as large as that of top panel  40   a.    
     For the use of light guide plate  72 , because there is a low risk of leaving the dust and dirt in the top surface of housing  34   b , optical pattern  37  may be provided in the top surface of light guide plate  72 . 
     Fourth Embodiment 
       FIG. 18  is a schematic sectional view illustrating relay  81  according to a fourth embodiment of the present invention. In the fourth embodiment, optical pattern  82  is formed in the bottom surface of optical pattern region  36  defined in a predetermined region of top panel  40   a . Pilot lamp  33  is arranged on an obliquely lower side of optical pattern region  36  such that the optical axis of pilot lamp  33  is oriented towards the horizontal direction or the direction looking up to top panel  40   a  from the horizontal direction within a spread angle of pilot lamp  33 . As used herein, the spread angle of pilot lamp  33  means an angle formed between the optical axis and the direction in which light intensity becomes half of light intensity in the optical axis direction of pilot lamp  33 . For example, assuming that pilot lamp  33  has the spread angle of about 25°, pilot lamp  33  is arranged such that the optical axis of pilot lamp  33  is oriented towards the horizontal direction or such that the optical axis is inclined upwards by about 25° or less with respect to the horizontal direction. 
     In the example of  FIG. 18 , pilot lamp  33  is arranged on the obliquely lower side of optical pattern region  36  such that the optical axis is oriented towards the substantially horizontal direction. When pilot lamp  33  spreads horizontally and vertically by about 25° around the optical axis, desirably pilot lamp  33  is arranged such that optical pattern region  36  falls within a vertical range of 0° to 25° and a horizontal range of ±25° based on the optical axis of pilot lamp  33 . Optical pattern  82  is a triangular shape in section or a pyramid-like prism, and optical pattern  82  is formed into the arc shape around the place where the light is incident to optical pattern region  36  when viewed from above (see  FIG. 6A ). As illustrated in  FIG. 18 , optical pattern  82  is designed such that the light incident from obliquely below is refracted and output in the direction substantially perpendicular to the top surface of top panel  40   a.    
     When the light emitted from pilot lamp  33  is incident to optical pattern  82  from obliquely below, the light incident to optical pattern  82  is refracted upwards by optical pattern  82 , and output towards the direction substantially perpendicular to the top surface of top panel  40   a . As a result, optical pattern region  36  of top panel  40   a  emits the light in the planar state. In the fourth embodiment, desirably optical pattern region  36  has the area of at least ⅕ times as large as that of top panel  40   a.    
     In relay  81  of the fourth embodiment, because the top surface of top panel  40   a  emits the light in the planar state, the light is easily seen from all directions thus improving visibility. Particularly, in the case that a plurality of relays  81  are arrayed, the light is not interrupted by adjacent relay  81 , the relay  81  emitting the light is not confused with adjacent relay  81 , and thus the relay  81  emitting the light is easily distinguishable. 
     Modification of Fourth Embodiment 
       FIG. 19  is a schematic sectional view illustrating a relay according to a first modification of the fourth embodiment. In the relay of the first modification of the fourth embodiment, diffusion optical system  55  is provided on the top surface of top panel  40   a  above pilot lamp  33  in relay  81  of the fourth embodiment. Therefore, the light leaking upwards from pilot lamp  33  is diffused by diffusion optical system  55  and seen from all directions, thereby the visibility of the operation display becomes better in the relay. 
       FIG. 20  is a schematic sectional view illustrating a relay according to a second modification of the fourth embodiment. In the relay of the second modification of the fourth embodiment, diffusion optical system  83  (similar to diffusion optical system  55 ) is provided on the whole top surface of top panel  40   a  in relay  81  of the fourth embodiment. Therefore, the light output from optical pattern region  36  is diffused by diffusion optical system  83 , the light leaking upwards from pilot lamp  33  is diffused by diffusion optical system  55 , and the light emission of the whole top surface of top panel  40   a  is seen from all directions, thereby the visibility of the operation display becomes better in the relay. 
     As illustrated in  FIG. 21 , prism sheet  84  in which optical pattern  82  is formed may be arranged below top panel  40   a.    
     Fifth Embodiment 
       FIG. 22  is a schematic sectional view illustrating a method for handling the light leaking upwards from horizontally-installed pilot lamp  33 . In a fifth embodiment, through-hole  91  is made in top panel  40   a  above pilot lamp  33 , and a columnar light guide, namely, columnar member  92  made of a transparent resin is inserted in through-hole  91 . In the configuration of the fifth embodiment, when the light exiting upwards from pilot lamp  33  is incident to columnar member  92 , the light is reflected by an outer circumferential surface of columnar member  92 , and output from the top surface of columnar member  92 . Because the light output from the top surface of columnar member  92  spreads outwards, the light transmitted through columnar member  92  is easily recognized from a lateral direction. 
     Modification of Fifth Embodiment 
       FIG. 23A  illustrates a relay according to a first modification of the fifth embodiment. In the first modification of the fifth embodiment, columnar member  93  made of the transparent resin is molded and made integral with top panel  40   a . The bottom surface of columnar member  93  is molded into a spherical shape to provide convex lens  94 , and the top surface of columnar member  93  is subjected to a light diffusion treatment. The light incident from the bottom surface of columnar member  93  is formed into parallel light by convex lens  94 , passes through columnar member  93 , and is diffused by the top surface of columnar member  93 . As a result, light intensity P increases at the top surface of columnar member  93 , and the top surface of columnar member  93  uniformly emits the light. In the first modification of the fifth embodiment, because columnar member  93  is molded and made integral with top panel  40   a , a trouble of assembling columnar member  93  in top panel  40   a  is eliminated. 
     However, in the structure of  FIG. 23A , in the case that the position of columnar member  93  is shifted from the position of pilot lamp  33 , the light is easily seen in a certain direction but hardly seen on the opposite side as illustrated in  FIG. 23B . 
       FIG. 24A  illustrates a relay according to a second modification of the fifth embodiment, namely, an improved example of the first modification. In the second modification of the fifth embodiment, columnar projection  95  having a diameter smaller than that of columnar member  93  is provided on the top surface of columnar member  93 , and the top surface of columnar projection  95  is subjected to the light diffusion treatment. According to the configuration, even if the position of columnar member  93  is shifted from the position of pilot lamp  33  as illustrated in  FIG. 24B , a light intensity distribution of the light output from columnar projection  95  is hardly shifted, and the light is uniformly seen from all directions. 
     Sixth Embodiment 
       FIG. 25  is a schematic sectional view illustrating another method for handling the light leaking upwards from horizontally-installed pilot lamp  33 . In a sixth embodiment, circular V-groove  101  is formed around an axis, which passes through a substantial center of the light emission of pilot lamp  33  and is perpendicular to the top surface of top panel  40   a . A depth of circular V-groove  101  ranges from about 0.2 mm to about 1.5 mm. When circular V-groove  101  is provided above pilot lamp  33 , the light passing through V-groove  101  is radiated in a direction different from that of the light passing through the flat top surface of the top panel in which V-groove  101  is not formed. Therefore, because V-groove  101  is formed in top panel  40   a , the light is emitted upwards in a wide angle range from pilot lamp  33 , and the light can be recognized in a wide range to enhance the visibility of the operation display light. 
     As illustrated in  FIG. 26 , circular prism  102  may be provided in a bottom surface of top panel  40   a  below V-groove  101 . A height of circular prism  102  ranges from about 0.2 mm to about 1.5 mm. When circular prism  102  is provided in the bottom surface of top panel  40   a  in addition to V-groove  101  provided in the top surface of top panel  40   a , the light can be radiated when refracted in various directions, and the light can be recognized in the wider range to further enhance the visibility of the operation display light. 
     As illustrated in  FIG. 27 , concave curve  103  having a concave lens shape may be provided in the center of V-groove  101  in the top surface of top panel  40   a  and convex curve  104  having a convex lens shape may be provided in the center of circular prism  102  in the bottom surface of top panel  40   a . The light can be emitted in various directions from pilot lamp  33  because concave curve  103  and convex curve  104  are provided in the top and bottom surfaces of top panel  40   a , respectively. Therefore, the light can be recognized in the wider range to further enhance the visibility of the operation display light. 
     Optical Pattern Having Different Shape 
     In the above embodiments, optical pattern  37  has the triangular prism shape in section or the pyramid shape. However, optical pattern  37  is not limited to the triangular prism shape in section or the pyramid shape. For example,  FIG. 28  illustrates optical pattern  37  having a trapezoidal shape in cross-section. For example, optical pattern  37  may have a truncated square pyramid shape. Preferably a leading end surface of optical pattern  37  having the truncated square pyramid shape has a width W of several tens of micrometers or less. Preferably gap S between optical patterns  37  is less than or equal to several tens of micrometers. Optical pattern  37  having the truncated square pyramid shape can be used in both the light guide type in  FIGS. 7 to 17  and the projection type in  FIGS. 18 to 21 . 
     An object of an embodiment of the present invention is to improve the visibility of the pilot lamp incorporated in the relay. 
     In accordance with a first aspect of an embodiment of the present invention, in a relay in which a relay body and a light source are incorporated in a case, the light source emitting light in conjunction with operation of the relay body, a light guide is provided inside an outer surface of the case, the light guide is configured to take in the light emitted from the light source, to guide the light to a portion parallel to a top panel of the case, and to spread the light in the portion parallel to the top panel, and an optical pattern is provided in at least one of a top surface and a bottom surface of the portion parallel to the top panel, the optical pattern is configured to output, the light guided in the light guide to the portion parallel to the top panel, to outside the case from the top surface of the top panel. For example, the optical pattern may be a projection or a recess, the projection or the recess being formed in a prism shape. 
     According to the relay of the first aspect, because a predetermined region in the top panel of the relay can emit the light in a planar state, the light used to display the operation of the relay can be recognized from all directions, and the visibility of source light (pilot lamp) of the relay is improved. Even if the plurality of relays is arrayed, the light emitted from the light source is hardly interrupted by the adjacent relay, and the visibility is hardly degraded. Additionally, the risk that the light emitted from the light source is not seen due to the disturbance light is decreased because the relatively wide area of the top panel of the relay emits the light. 
     In the relay in accordance with the first aspect, preferably the optical pattern is arranged in a concentric circle around a place, in which the light is incident to a region where the optical pattern is formed when viewed from a direction perpendicular to the top panel. Accordingly, in the case that the light source is a small light source (point light source) such as an LED, the light emitted from the light source is reflected by the optical pattern, which allows the light to be efficiently output in the direction perpendicular to the top panel, which is outside the case and the top panel. 
     In the relay in accordance with the first aspect, preferably the optical pattern outputs the light to outside the case from the top surface of the top panel by totally reflecting the light guided in the light guide. Accordingly, the use of the total reflection eliminates necessity of a reflecting tape, and cost can be reduced. 
     In the relay in accordance with the first aspect, preferably the light guide is provided in the case, and the optical pattern is provided in a bottom surface of the top panel. Accordingly, the case can be used as the light guide, and the optical pattern is provided in the top panel of the case, so that enlargement of the relay can be avoided. 
     In the relay in accordance with the first aspect, the light source may be accommodated in a recess formed in the bottom surface of the top panel, and the light horizontally emitted from the light source may be incident to the top panel from a sidewall surface of the recess, for the light emitted from the light source to be incident to the case (light guide). Alternatively, the light source may be arranged below the top panel, a protrusion including a light incident surface may be projected from the bottom surface of the top panel at a position opposite to the light source, and the light emitted from the light source may be incident to the top panel from the light incident surface of the protrusion. 
     In the relay in accordance with the first aspect, an orientation and a position of the light source can freely be designed. For example, an inclined reflecting surface may be formed in the top surface of the case, the light emitted upward from the light source may be incident to the top panel, and the light may be guided along the top panel by reflecting the light incident to the top panel using the reflecting surface. Alternatively, a first reflecting surface inclined with respect to a surface perpendicular to a thickness direction of a sidewall plate of the case may be provided in an outer surface of the sidewall plate of the case, an inclined second reflecting surface may be formed in a corner portion between the top surface and a side surface of the case, the light horizontally emitted from the light source may be incident to the sidewall plate, the light may be guided along the sidewall plate by reflecting the light incident to the sidewall plate using the first reflecting surface, and the light may be guided along the top panel by reflecting the light using the second reflecting surface. 
     In the relay in accordance with the first aspect, preferably the light guide is a light guide plate that is arranged opposite to the bottom surface of the top panel, the light source is arranged opposite to the light incident surface of the light guide plate, and the optical pattern is provided in one of a top surface and a bottom surface of the light guide plate. It is only necessary to insert the light guide plate in which the optical pattern is provided in the case. Accordingly, versatility is enhanced. 
     In the relay in accordance with the first aspect, preferably a transparent operation checking window is formed in the top panel in a region outside the region, where the optical pattern is provided, when viewed from the direction perpendicular to the top panel. Accordingly, the inside of the relay is seen through the operation checking window, so that the operating state of the relay can be checked. 
     In the relay in accordance with the first aspect, preferably a plurality of types of optical patterns are formed in the light guide, the optical patterns are configured to reflect the light guided in the light guide in different directions. Accordingly, when a character, a numerical character, or a mark is drawn by one of the optical patterns, the corresponding character, numerical character, or mark can brightly be displayed only when viewed from a specific direction. 
     In accordance with a second aspect of the embodiment of the present invention, in a relay in which a relay body and a light source are incorporated in a case, the light source emitting light in conjunction with operation of the relay body, an optical pattern is arranged below a top surface of a top panel of the case, the optical pattern is configured to refract the light incident from a bottom surface side and to output the light to outside the case from the top surface of the top panel, and the light source is arranged below the optical pattern such that an optical axis of the light source is oriented toward a horizontal direction or a direction looking up to the top panel from the horizontal direction within a spread angle of the light source. 
     According to the relay of the second aspect, because the predetermined region in the top panel of the relay can emit the light in the planar state, the light used to display the operation of the relay can be recognized from all directions, and the visibility of the source light (pilot lamp) of the relay is improved. Even if the plurality of relays is arrayed, the light emitted from the light source is hardly interrupted by the adjacent relay, and the visibility is hardly degraded. Additionally, the risk that the light emitted from the light source is not seen due to the disturbance light is decreased because the relatively wide area of the top panel of the relay emits the light. 
     In the relay in accordance with the second aspect, preferably the optical pattern is provided in a bottom surface of the top panel. It is not necessary to use the additional member for providing the optical pattern. Accordingly, downsizing of the relay can be achieved and the cost can be reduced. 
     In the relay in accordance with the first and second aspects, preferably, in the top panel, the light is output to outside the case from a region having an area of at least ⅕ times as large as that of the top panel. When the light emission area is smaller than ⅕ times the area of the top panel, possibly the visibility of the light emitted from the light source is degraded depending on a use state or the disturbance light. 
     In the relay in accordance with the first and second aspects, a diffusion optical system may be formed in the top panel in a region corresponding to the optical pattern. Accordingly, an output direction of the light output from the top panel is spread, so that the light emitted from the light source can be recognized in the wider range to improve the visibility. 
     In the relay in accordance with the first and second aspects, the diffusion optical system or a columnar light guide may be provided in the top panel above the light source, when the light source is arranged below the top panel and the optical axis of the light source is parallel to the top panel. Accordingly, the light leaking upward from the light source can be used as the operation checking light, and the relay can look more brightly. 
     The unit solving the problem in the embodiment of the present invention has the feature in which the above constituents are combined, and various variations can be made by the combination of the constituents.