Abstract:
A transmitter having a structure causing no complicated manufacturing process and no damage of a sealing rubber and capable of certainly preventing an electronic substrate from coming off in exchanging a battery is provided. An inner plate is a component, which has a bending type of unseparated segmentation structure and which is molded into one body, and the inner plate is molded with protruded portions engaging with grooves formed in an inner surface of an upper case and elastic pieces engaging with a periphery of the electronic substrate. The bent inner plate is placed on the electronic substrate and a force for canceling the bending state is added so that the protruded portions would engage with the grooves of the upper case and the elastic pieces would engage with the periphery of the electronic substrate.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a transmitter, particularly, a transmitter for a remote keyless entry system, for example, which is required to have a certain waterproof function for exclusive outdoor use and to be easy to carry out an operation of exchanging a built-in battery, the operation being necessary even though it is not frequently required.  
         [0003]     2. Description of Related Art  
         [0004]     A remote keyless entry system is a convenient system in which operating only a push button of a transmitter housed in a case as small as a matchbox allows a door to be locked or unlocked without using any mechanical key. There is also a developed type of system in which no operation of pushing a push button of a transmitter is necessary. In the developed type of system, a door of a vehicle can be locked or unlocked by pushing an entry button of the door of a vehicle with a transmitter putted on. Accordingly, it is not necessary to take out the transmitter from a pocket every time.  
         [0005]     Such transmitters are all used outdoors, and thus, a waterproof countermeasure against rain and such is essential. Moreover, they are operated by means of a disposable battery, and therefore, it should be considered whether an operation of exchanging the battery is easy to perform or not.  
         [0006]      FIG. 4  shows a first conventional example.  FIG. 4  shows a structure similar to the one introduced in Paragraphs [0038] to [0039] in JP-A-11-81762. In  FIG. 4 , a transmitter  1  includes a main body portion  2 , which comprises cases  2   a  and  2   b  divided into upper and lower two parts and which is as small as a matchbox, a battery  3 , which is housed in a battery housing portion  2   d  in the main body portion  2  through a battery housing hole  2   c  formed in a bottom of the case  2   a , an O-ring  4  for waterproofing mounted on the periphery of the battery housing hole  2   c  and a circular rid  5  for closing the battery housing hole  2   c  with the O-ring  4  inserted therebetween. On a surface of the case  2   b  (a surface on the back side, which is not shown), provided are various kinds of push button such as a locking button and an unlocking button, for example.  
         [0007]     An advantage of the first conventional example is that an operation of exchanging the battery  3  is easy. That is to say, fitting a familiar coin or such in a groove  5   a  of the circular rid  5  and turning the coin allow the circular rid  5  to be easily taken off. The battery  3  can be thus exchanged without using any special tool.  
         [0008]     On the other hand, the first conventional example has following disadvantages. First, the surface of the main body portion  2  has little free space, so that there is only a small space available for sticking an emblem of a manufacturer or a radio frequency identification sticker, for example. This causes little freedom in designing. Namely, on the surface of the case  2   a , provided are the battery housing hole  2   c  and the circular rid  5  while various kinds of push button are provided on the surface of the case  2   b , so that an emblem of a manufacturer, a radio frequency identification sticker or such can be stuck only in an extremely small range excluding the above components. This is one of disadvantages. Further, one of waterproofed parts of the transmitter  1  is a part located between the battery housing hole  2   c  of the case  2   a  and the circular rid  5 . In the case that the O-ring  4  is improperly mounted or fails to be mounted in an operation of exchanging the battery  3 , rain water or such would enter from the part, so that a trouble would be caused for an electronic substrate in the main body portion  2 . This is another disadvantage.  
         [0009]      FIG. 5  shows a second conventional example.  FIG. 5  shows a structure similar to the one introduced in Paragraph [0042] in JP-A-2003-201781. In the second conventional example, a transmitter  6  also includes a main body portion  7 , which comprises cases  7   a  and  7   b  divided into upper and lower two parts and which is as small as a matchbox, similar to the first conventional example described above. There is, however, no “circular rid for exchanging a battery” like the case of the first conventional example described above. The cases  7   a  and  7   b  divided into upper and lower two parts are arranged to be able to be disassembled whenever exchange of a battery  8  is necessary. Such a way of exchanging a battery is called a “case disassembling type”.  
         [0010]     In an inner surface of the case  7   a , provided are a spring characteristic terminal  7   c  in contact with one electrode of a battery  8 , a conductive sheet  7   d  electrically connected to the spring characteristic terminal  7   c  and a waterproof seal  7   e  on the periphery of an opening of the case  7   a . On the other hand, in an inner surface of the case  7   b , provided are a spring characteristic terminal  7   f  in contact with the other electrode of the battery  8 , an electronic substrate  9  on which a predetermined electronic circuit is mounted, the electronic circuit using as a power source a terminal voltage of the battery  8  supplied through the above two spring characteristic terminals  7   c  and  7   f  to operate, and a holding body  10  for holding the periphery of the battery  8  to perform positioning.  
         [0011]     In the second conventional embodiment, there is no circular rid for exchanging a battery, so that enough free space is secured on the surface of the main body portion  7 . This leads to an advantage that the freedom for sticking an emblem of a manufacturer, a radio frequency identification sticker or such is large. Moreover, there is another advantage that elastic fitting (snap connection) between the cases  7   a  and  7   b  divided into upper and lower two parts allows the main body portion  7  to be easily disassembled by means of a coin or a nail in some cases, for example, without any special tool, so as to easily exchange the battery  8 . Further, there is only one waterproof part between the cases  7   a  and  7   b  divided into upper and lower two parts (a waterproof seal  7   e ). Accordingly, fixed adhesion of the waterproof seal  7   e  prevents the waterproof seal  7   e  from coming off in an operation of exchanging the battery  8 . This is also an advantage of the second conventional example. Many recent transmitters for a remote keyless entry system are, thus, of the case disassembling type because of the above advantages.  
         [0012]     The above second conventional example (a case disassembling type of transmitter) has superior advantages that the freedom for sticking an emblem of a manufacturer, a radio frequency identification sticker or such is large, that battery exchange is easy and that a waterproof performance can be maintained. In the second conventional example, however, the cases  7   a  and  7   b  divided into upper and lower two parts are disassembled for exchanging the battery  8 , so that the electronic substrate  9  sometimes comes off in an exchanging operation. In order to avoid the above, it is possible in some cases to take measures so that the electronic substrate  9  would be fixed to the case  7   b  by means of a screw  11 , as shown in  FIG. 5 , for example. Such a measure by means of a screw, however, is not preferable since it causes a complicated manufacturing process.  
         [0013]      FIG. 6  shows a third conventional example in which a structure is improved with respect to the above disadvantages.  FIG. 6  is a sectional view of an integral part of a structure in assembling a transmitter, the structure being similar to the one introduced in Paragraphs [0012] to [0015] in JP-A-2001-339176. In  FIG. 6 , an elastic piece  12   a  of an inner case  12  is first engaged with a periphery of the electronic substrate  9  to fit the electronic substrate  9  and the inner case  12  into a sealing rubber  13  with the engagement maintained. The assembled body (the electronic substrate  9 +the inner case  12 +the sealing rubber  13 ) is then pushed into the case  7   b  so that a protrusion  13   a  of the sealing rubber  13  (a pressure deformation part formed by a convex portion  12   b  of the inner case  12 ) would engage with a hollow  7   g  on an inner circumferential side surface of the case  7   b . Such assembling finally allows the case  7   b , the sealing rubber  13 , the inner case  12  and the electronic substrate  9  to be formed into one body, so that the electronic substrate  9  does not come off in exchanging a battery.  
         [0014]     In the above third conventional example, however, the electronic substrate can be prevented from coming off in exchanging a battery while the following disadvantage may be caused. That is to say, large friction occurs between the protruded portion  13   a  of the sealing rubber  13  and a protruded portion  7   f  of the case  7   b  in fitting the electronic substrate  9  and the inner case  12  into the sealing rubber  13 , and thereby, damage such as breakage of a friction part of the sealing rubber  13  may be caused in some cases.  
         [0015]     In view of the above, the invention relates to a structure capable of certainly preventing an electronic substrate from coming off in exchanging a battery by disassembling a case and is to provide a transmitter, which allows the structure to be put into practice without causing a complicated manufacturing process and any damage of a sealing rubber.  
       SUMMARY OF THE INVENTION  
       [0016]     A transmitter in accordance with the invention comprises: an upper case having the shape of a box with a bottom; a sealing rubber covering an inner surface of the upper case; an electronic substrate fitted in the sealing rubber; and an inner plate for preventing the electronic substrate from coming off, and the transmitter is characterized in that the inner plate is a component, which has a bending type of unseparated segmentation structure and which is molded into one body, and the inner plate is molded with at least a protruded portion engaging with a groove formed in the inner surface of the upper case and an elastic piece engaging with a periphery of the electronic substrate, and that the bent inner plate is placed on the electronic substrate and a force for canceling the bending state is added so that the protruded portion would engage with the groove of the upper case and the elastic piece would engage with the periphery of the electronic substrate.  
         [0017]     The “bending state” in the above context means a state in which the inner plate is bent into the shape of “V” (see  FIGS. 2B and 3A ) while the “canceling the bending state” means that the inner plate is changed in shape from the “V” shape to a straight line (see  FIG. 3B ).  
         [0018]     In the invention, only simple operations of bending and placing the inner plate on the electronic substrate and adding a force for canceling the bending state allow the upper case, the sealing rubber and the electronic substrate to be formed into one body.  
         [0019]     In accordance with the invention, an upper case, a sealing rubber and an electronic substrate can be formed into one body by means of an inner plate, so that the electronic substrate can be certainly prevented from coming off in disassembling a case for exchanging a battery.  
         [0020]     Further, forming the above components into one body is enabled by a simple operation of only adding a predetermined stress on the bent inner plate, and therefore, it does not cause a complicated manufacturing process.  
         [0021]     Moreover, the sealing rubber receives no strong friction in forming the above components into one body. Accordingly, the sealing rubber is not likely to be damaged while the waterproof performance is not deteriorated.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  shows a structure of a transmitter  20  according to the present embodiment;  
         [0023]      FIG. 2  illustrates an assembling process of the transmitter  20 ;  
         [0024]      FIG. 3  illustrates an assembling process of the transmitter  20 ;  
         [0025]      FIG. 4  shows a first conventional example;  
         [0026]      FIG. 5  shows a second conventional example; and  
         [0027]      FIG. 6  is a sectional view of an integral part of a transmitter in assembling in a third conventional example. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     An embodiment of the invention will be described hereinafter on the basis of the drawings. It should be clearly understood that various detailed specification, illustration and examples of numerals, a series of characters and other marks in the following description are only for reference in order to explain the idea of the invention and all or a part of the above limits no idea of the invention. A well-known method, well-known procedure, well-known architecture, well-known circuitry and such (referred to as “well-known matters”, hereinafter) are omitted from detailed description. This is for the purpose of simplifying description and not for the purpose of intentionally eliminating all or a part of the well-known matters. The well-known matters are naturally included in the following description since a person skilled in the art should have known the well-known matters at the time the invention is filed.  
         [0029]      FIG. 1  shows a structure of a transmitter  20  in accordance with the embodiment. In  FIG. 1 , the transmitter  20  comprises an upper case  21  shown in the lowest part of the drawing, a button knob  22  mounted on the inner side of the upper case  21 , a sealing rubber  23 , an electronic substrate  24 , an inner plate  25 , a battery  26  and a lower case  27  for closing the upper case  21 . The word “upper” indicates here a surface for operating a button in using the transmitter  20  (an upward surface, generally) while the word “lower” indicates an opposite surface (a back surface) thereof. The surface for operating a button of the upper case  21  is placed on the operation table or the like in assembling the transmitter  20 , as shown in  FIG. 1 .  
         [0030]     Now, respective parts will be described in detail. The upper case  21  is formed into the shape of a box, which has a bottom and whose upper surface is opened and which is as small as a matchbox. The upper case  21  has a space portion  21   a  therein for housing the button knob  22 , the sealing rubber  23 , the electronic substrate  24 , the inner plate  25  and the battery  26 . The space potion  21   a  is provided in its bottom surface with a plurality of button holes  21   b  to  21   g . The space portion  21   a  is further provided at a little bit upper place from the bottom of a side circumference thereof with a step portion  21   h  for mounting the sealing rubber  23  and a notch  21   i  for positioning the sealing rubber  23 .  
         [0031]     In two side surfaces located on the shorter side edges of the upper case  21  among the four side surfaces of the space portion  21   a , formed are groove portions  21   j  and  21   k  for locking the inner plate  25 , respectively. Furthermore, on the periphery of an opening of the upper case  21 , formed all over the periphery is an engaging portion  21   m  for elastically engaging with the lower case  27  while an outward protruded portion is provided in a part of the periphery of the opening to form therein a hole  21   n  for holding a key ring or the like.  
         [0032]     The button knob  22  is molded in whole out of a hard elastic body such as hard rubber. The button knob  22  includes push button portions  22   a  to  22   f  respectively corresponding to the plural button holes  21   b  to  21   g  formed in the bottom surface of the space portion  21   g  of the upper case  21 . The push button portions  22   a  to  22   f  are exposed outward from the plural button holes  21   b  to  21   g  formed in the bottom surface of the space portion  21   g  of the upper case  21  when the transmitter  20  is completely assembled. A user pushes the push button portions  22   a  to  22   f.    
         [0033]     The sealing rubber  23  is molded out of a soft elastic body such as soft rubber. The sealing rubber  23  includes a substrate housing portion  23   a  in the shape of a box, which has a bottom and whose upper surface only is opened, and a collar  23   b  mounted so as to be pressured between peripheries of the upper case  21  and the lower case  27  in elastic engagement of the upper case  21  and the lower case  27 . When the upper case  21  is elastically engaged with the lower case  27 , the substrate housing portion  23   a  is intercepted from the air for the purpose of waterproofing.  
         [0034]     In a side surface of the substrate housing portion  23   a , formed is a step portion  23   c  for mounting the electronic substrate  24 . In the bottom surface of the substrate housing portion  23   a , formed is a proper number of column-shaped protrusions  23   d  corresponding to each of the above-mentioned plural push buttons  22   a  to  22   f  of the button knob  22 . Further, in two side surfaces located on the shorter side edges of the upper case  21  among the four side surfaces of the substrate housing portion  23   a , formed are groove portions  23   e  and  23   f  for locking the inner plate  25 , respectively.  
         [0035]     On the electronic substrate  24 , mounted is an electronic circuit necessary for operating the transmitter  20 . In the electronic substrate  24 , a variety of devices (not shown) such as a semiconductor integrated circuit, a resistance and a capacitor, an electrode portion for a battery  24   a  and push button switches respectively corresponding to the above-mentioned plural push buttons  22   a  to  22   f  of the button knob  22  (which are provided on the back side, and thereby, not shown) are mounted on front and back surfaces of a printed board. Notches  24   b  and  24   c  are respectively formed in the vicinity of a substantial center of longitudinal side surfaces of the electronic substrate  24 . Later-mentioned elastic pieces  25   f  and  25   g  formed in the inner plate  25  engage with the notches  24   b  and  24   c.    
         [0036]     The inner plate  25  has an unseparated double segmentation structure in a bending manner. The inner plate  25  is formed into one body in whole from synthetic resin such as ABC resin, polycarbonate, polypropylene and modified PPO, for example. In the embodiment, the inner plate  25  is divided into a first plate portion  25   b  and a second plate portion  25   c  by a thin dividing line portion  25   a . The two plate portions (the first plate portion  25   b  and the second plate portion  25   c ) are arranged to be able to bend in the shape of “V” at the dividing line portion  25   a.    
         [0037]     In two side surfaces located on the shorter side edges of the upper case  21  among the four side surfaces of the inner plate  25 , formed are protruded portions  25   d  and  25   e , respectively. The protruded portions  25   d  and  25   e  engage with the groove portions  21   j  and  21   k  of the upper case  21  through the groove portions  23   e  and  23   f  of the sealing rubber  23  when the transmitter  20  is completely assembled. Further, in the longitudinal side surfaces of the inner plate  25 , respectively formed are the elastic pieces  25   f  and  25   g , which engage with and hold the notch portions  24   b  and  24   c  provided on the periphery of the electronic substrate  24  when the transmitter  20  is completely assembled. The inner plate  25  is further provided with a hole  25   h  for exposing an electrode in a bottom surface of the battery  26  and a portion  25   i  for positioning and holding a side surface of the battery  26 .  
         [0038]     Finally, the lower case  27  has a shape almost similar to that of the upper case  21 . The lower case  27  is different from the upper case  21 , however, at least in that there is no opening other than a lower surface opening.  
         [0039]      FIGS. 2 and 3  illustrate an assembling process of the transmitter  20 . The transmitter  20  is assembled in accordance with the following procedure. First, the upper case  21  is placed on an operation table with the opening surface thereof faced upward. The button knob  22 , the sealing rubber  23  and the electronic substrate  24  are mounted in order in the space portion  21   a  of the upper case  21  (see  FIG. 2A ). The inner plate  25  is then bent into the shape of “V” at the dividing line portion  25   a , placed on the electronic substrate  24  as it is and thrust with a pressure by means of a finger or such at the dividing line portion  25   a  (see  FIGS. 2B and 3A ).  
         [0040]     The above pressure-thrusting operation causes the inner plate  25  to change in shape so that the first plate portion  25   b  and the second plate portion  25   c  would form a straight line. In a step of completing the change in shape, the protruded portions  25   d  and  25   e  of the inner plate  25  are inserted in the groove portions  21   j  and  21   k  of the upper case  21  through the groove portions  23   e  and  23   f  of the sealing rubber  23  (see  FIG. 3B ). The inner plate  25  and the upper case  21  (and the electronic substrate  24 , the sealing rubber  23  and the button knob  22 , which are sandwiched therebetween) are thus formed into one body (see  FIG. 2C ).  
         [0041]     In the step of completing the change in shape from a “V” shape to a straight line, the elastic pieces  25   f  and  25   g  of the inner plate  25  hold the notches  24   b  and  24   c  of the electronic substrate  24  (see  FIG. 3C ). The inner plate  25  and the upper case  21  (and the electronic substrate  24 , the sealing rubber  23  and the button knob  22 , which are sandwiched therebetween) are thus kept to be in one body so as not to be separated even after the pressure on the dividing line portion  25   a  of the inner plate  25  is released.  
         [0042]     The battery  26  is loaded after the components from the inner plate  25  to the upper case  21  are formed into one body, as described above, and finally, the lower case  27  is elastically fitted in the upper case  21  to complete the transmitter  20 .  
         [0043]     In view of the above, the following effects can be obtained in accordance with the transmitter  20  in the embodiment.  
         [0044]     (1) There is no circular rid for exchanging a battery (see Sign  5  in  FIG. 4 ). Accordingly, free space on the surfaces of the electronic substrate  24  and the lower case  27  is sufficiently secured, so that the freedom for sticking an emblem of a manufacturer, a radio frequency identification sticker or such is large.  
         [0045]     (2) The waterproof part is only the peripheries of the upper case  21  and the lower case  27  and certainly sealed by means of the collar portion  23   b  of the sealing rubber  23 . This allows a certain waterproof function to be secured.  
         [0046]     (3) In exchanging the battery  26 , the battery  26  can be easily exchanged only by inserting a coin, a nail and the like in the elastically fitting portion between the upper case  21  and the lower case  27  (the peripheries of the upper case  21  and the lower case  27 ) for separation and taking off the lower case  27 .  
         [0047]     (4) In addition to the above, the inner plate  25 , the electronic substrate  24 , the sealing rubber  23 , the button knob  22  and the upper case  21  are kept to be in one body (see  FIG. 2C ) in exchanging the battery  26 , so that the electronic substrate  24  does not come off.  
         [0048]     (5) Moreover, the electronic substrate  24  is provided behind the inner plate  25 , in other words, the electronic substrate  24  is not exposed. This causes no inconvenience that a person unintentionally touches the electronic substrate  24 . Accordingly, an electric trouble (such as insulation defect or rusting due to adherence of finger grease or water) of the electronic substrate  24  can be prevented.  
         [0049]     (6) In assembling the transmitter  20 , added is a strong force on the groove portions  23   e  and  23   f  of the sealing rubber  23  through the protruded portions  25   d  and  25   e  of the inner plate  25 . A direction in which the force is applied is not a direction in which friction in the above-mentioned third conventional example is generated but a “thickness direction” of the groove portions  23   e  and  23   f  of the sealing rubber  23  (see  FIG. 3B ). Therefore, the sealing rubber  23  is less likely to be broken than the case of the third conventional example and a certain waterproof function can be maintained.