Abstract:
Electronic equipment having an easily replaceable input device allowing various types of input operations, wherein the input device with a first signal generating part is fitted to the opening part of a cabinet from the outside and positioned, a lid-like cover is detachable from the cabinet and fixes the input device when installed on the opening part of the cabinet, and a second signal generating part is installed in the cabinet and functions in combination with the first signal generating part, whereby, since the input device is fixed by merely installing the lid-like cover. On the cabinet, the input device can be easily replaced without taking out a patch board having the second signal generating part thereon by opening the cabinet.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to an electronic apparatus equipped with an input device enabling various inputs when an operating member undergoes required operation.  
         BACKGROUND ART  
         [0002]    Recently, electronic apparatuses equipped with various input devices have come into widespread use. One of such conventional electronic apparatuses will be described hereinafter with reference to FIG. 14.  
           [0003]    [0003]FIG. 14 is a perspective view of an essential part of the conventional electronic apparatus.  
           [0004]    As shown in this drawing, terminal  2  of input device  1  is electrically and mechanically connected in place to wiring board  3  of the electronic apparatus by soldering, whereby input device  1  is mounted to wiring board  3 .  
           [0005]    This input device  1  includes operating member  4  projecting upward. When an operator moves operating member  4  in a specified direction with a hand or a finger, input device  1  outputs an electric signal corresponding to this operation.  
           [0006]    This electric signal is sent from terminal  2  of input device  1  to a microcomputer (not shown) or the like of the electronic apparatus via wiring board  3 , and consequently, the electronic apparatus starts a specific function corresponding to this signal.  
           [0007]    A top side of housing  5  serving as an upper case of the electronic apparatus has opening  5 A permitting the passage of operating member  4  of input device  1 . Through this opening  6 A, only operating member  4  projects on the top side of housing  5 .  
           [0008]    A variety of functions of the thus-configured conventional electronic apparatus equipped with input device  1  can be started by manipulating operating member  4  of input device  1  that projects upward from housing  5  or is exposed over housing  5 .  
           [0009]    Failed input device  1  of the conventional electronic apparatus described above is replaced in the following manner.  
           [0010]    Housing  5  of the electronic apparatus is opened, and wiring board  3  is removed. Subsequently, failed input device  1  is removed by detaching soldered terminal  2  of input device  1  from wiring board  3 . Thereafter, a new input device is mounted to wiring board  3 , and the electronic apparatus is reassembled. The replacement is thus extremely troublesome.  
         DISCLOSURE OF THE INVENTION  
         [0011]    An electronic apparatus of the present invention includes an input device, a housing, a cover, and a second signal generator.  
           [0012]    The input device includes a first signal generator. The housing includes an opening in which the input device is placed externally and positioned. The cover can be detached from the housing and fixes the input device when installed in the opening of the housing. The second signal generator is provided inside the housing and functions in combination with the first signal generator.  
           [0013]    The input device installed in this electronic apparatus can be removed by just detaching the cover from the housing. Thereafter, placing a new input device in the opening and reinstalling the cover on the housing are all that is needed to allow the new input device to function electrically and mechanically. The replacement of the input device is thus easy, eliminating the need to open the housing and to electrically reconnect the second signal generator provided inside the housing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is an exploded perspective view of an electronic apparatus in accordance with a first exemplary embodiment of the present invention.  
         [0015]    [0015]FIG. 2 is a conceptual illustration of a housing seen from inside the housing when a cover, which is an essential element in the first embodiment, is mounted.  
         [0016]    [0016]FIG. 3 is an exploded perspective view of an electronic apparatus in accordance with a second exemplary embodiment of the present invention.  
         [0017]    [0017]FIG. 4 is a sectional view of the electronic apparatus of FIG. 3.  
         [0018]    [0018]FIG. 5 is a top plan view of the electronic apparatus of FIG. 3 from which a housing and a case of a trackball device are omitted.  
         [0019]    [0019]FIG. 6 is a sectional view taken along line A-A of FIG. 5.  
         [0020]    [0020]FIG. 7 is a top plan view of the electronic apparatus of FIG. 3 from which the housing, the case of the trackball device, a ball and rollers are omitted.  
         [0021]    [0021]FIG. 8 is a sectional view taken along line X-X of FIG. 5, illustrating the trackball device in rolling operation.  
         [0022]    [0022]FIG. 9 is a sectional view taken along line X-X of FIG. 5, illustrating the trackball device in pressing operation.  
         [0023]    [0023]FIG. 10 is a top plan view of an electronic apparatus, from which a housing, a case of a trackball device, a ball and rollers are omitted, in accordance with a third exemplary embodiment of the present invention.  
         [0024]    [0024]FIG. 11 is a perspective view of an essential part of an electronic apparatus in accordance with a fourth exemplary embodiment of the present invention.  
         [0025]    [0025]FIG. 12 is an exploded perspective view of the electronic apparatus of FIG. 11.  
         [0026]    [0026]FIG. 13 is a sectional view taken along line B-B of FIG. 12, illustrating the electronic apparatus in complete condition.  
         [0027]    [0027]FIG. 14 is a perspective view of an essential part of a conventional electronic apparatus. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Exemplary embodiments of the present invention will be demonstrated hereinafter with reference to the accompanying drawings.  
         [0029]    (Exemplary Embodiment 1)  
         [0030]    [0030]FIG. 1 is an exploded perspective view of an electronic apparatus in accordance with the first exemplary embodiment of the present invention.  
         [0031]    [0031]FIG. 2 illustrates a housing seen from inside the housing when a cover, which is an essential element of the electronic apparatus, is mounted.  
         [0032]    As shown in the drawings, substantially square input device  11  is constructed of component case  12  made of resin, first signal generators  13  provided inside case  12 , and operating member  11 A, and is installed in housing  14  of the electronic apparatus.  
         [0033]    Housing  14  is provided with locating opening  15  large enough to receive case  12  of input device  11 .  
         [0034]    This opening  15  is a combination of circular opening  15 A provided in a top side of housing  14  and having a larger diameter than component case  12  in size, square opening  15 B concentric with circular opening  15 A positioned above square opening  15 B and matching up with case  12  in shape, and four retaining openings  15 C each protruding outward from the middle of each side of square opening  15 B.  
         [0035]    In regard to combination with cover  19  (described later), retaining openings  15 C are preferably formed so that a circular arc connecting respective outer peripheries of four retaining openings  15 C will be similar in shape to circular opening  15 A and will equal or will be smaller than opening  15 A in size.  
         [0036]    By having square opening  15 B and retaining openings  15 C, opening  15  defines projections for housing  14 . These projections referred to as stepped parts  15 D are flat, have the same height and are positioned below the top side of housing  14 .  
         [0037]    Housing  14  accommodates internal members including wiring board  16 .  
         [0038]    Second signal generators  17  are arranged on wiring board  16 . Each one of these generators  17  produces a specified output by functioning in combination with corresponding first signal generator  13  provided inside input device  11 .  
         [0039]    Second signal generator  17  has terminal  18 , which is soldered to wiring board  16 .  
         [0040]    Cover  19  with which circular opening  15 A is closed has a smaller diameter than circular opening  15 A and is constructed of ring-shaped flat plate  20  having through hole  20 A in the middle thereof, and four L-shaped poles  21 - 24  projecting downward from an outer border of a bottom surface of flat plate  20 . L-shaped poles  21 - 24  have respective horizontal parts  25 - 28  not connecting with flat plate  20 , and these horizontal parts  25 - 28  have respective grooves  29 - 30  in their respective outer sides.  
         [0041]    L-shaped poles  21 - 24  are provided at an equal angular pitch at a bottom side of cover  19 , and horizontal parts  25 - 28  have respective leading ends oriented in the same direction.  
         [0042]    Each one of horizontal parts  25 - 28  is shorter than each retaining opening  15 C of opening  15 .  
         [0043]    After input device  11  is fit and positioned in square opening  15 B of opening  15  of housing  14 , cover  19  is placed in such a manner that L-shaped poles  21 - 24  are inserted into respective retaining openings  15 C. Cover  19  is thereafter turned clockwise with the bottom surface of ring-shaped flat plate  20  urged against stepped parts  15 D, whereby each one of horizontal parts  25 - 28  of poles  21 - 24  of cover  19  hitches on a bottom surface of corresponding stepped part  15 D. Cover  19  is thus mounted to housing  14 , thereby fixing input device  11 .  
         [0044]    When cover  19  is turned clockwise, grooves  29 - 32  formed in the respective outer sides of L-shaped poles  21 - 24  of cover  19  engage with respective projections  33 - 36  provided inside housing  14 . This prevents cover  19  from easily coming off when counterclockwise external force acts on cover  19 .  
         [0045]    It is visually preferable that the thickness of flat plate  20  is equal to the depth of circular opening  15 A so that a top surface of cover  19  will be flush with the top side of housing  14  when cover  19  is secured by housing  14 .  
         [0046]    When cover  19  is secured by housing  14 , input device  11  is fixed without fail because input device  11  is sandwiched vertically between wiring board  16  and cover  19  with its component case  12  fitting in square opening  15 B.  
         [0047]    According to the present embodiment described above, just installing cover  19  to housing  14  facilitates the installation of input device  11 .  
         [0048]    An operation of the electronic apparatus thus mounted with input device  11  will be described hereinafter.  
         [0049]    When operating member  11 A of input device  11  is operated with a hand, a finger or the like, first signal generator  13  operates in synchronization with the movement of operating member  11 A. Here, a signal is produced and transmitted to corresponding second signal generator  17  disposed on wiring board  16 . This second signal generator  17  then sends a specified output from its terminal  18  to an electronic device such as a microcomputer (not shown) via wiring board  16 , and consequently, the electronic apparatus starts a specific function corresponding to the signal.  
         [0050]    When the operation of operating member  11 A of input device  11  is stopped, first and second signal generators  13 ,  17  stop their respective operations and return to a state in which no output signal is generated.  
         [0051]    Input device  11  is replaced in the following manner. First, cover  19  is turned counterclockwise with force great enough to disengage grooves  29 - 32  of L-shaped poles  21 - 24  from respective projections  33 - 36  until each one of horizontal parts  25 - 28  of poles  21 - 24  that is hitched on the bottom surface of stepped part  15 D of housing  14  returns to corresponding retaining opening  15 C. Cover  19  is then lifted off from housing  14 .  
         [0052]    Next, input device  11  positioned in square opening  15 B of housing  14  is removed, and new input device  11  is then placed in opening  15 B. Thereafter, cover  19  is reinserted in opening  15  of housing  14  and turned clockwise to hitch each one of horizontal parts  25 - 28  of its poles  21 - 24  on the bottom surface of each stepped part  15 D and to engage grooves  29 - 32  formed in the respective outer sides of horizontal parts  25 - 28  with respective projections  33 - 36 . Consequently, new input device  11  is fixed by stepped parts  15 D of housing  14 , wiring board  16  and cover  19 .  
         [0053]    In a typical electronic apparatus, input device  11  having a mechanically movable part such as operating member  11 A is well known for its high frequency of failure. Input device  11  of the present invention is superior in maintenance because as described above, device  11  can be replaced with ease when failed.  
         [0054]    In cases where input device  11  has failed, repair is simply a matter of replacing device  11  in the simple manner described above, so that there is no need to troublesomely solder first signal generators  13  of input device  11 , second signal generators  17  and others to wiring board  16  and to detach them from board  16 .  
         [0055]    Cover  19  may be fixed to housing  14  by snap fitting or screwing instead of turning the one having L-shaped poles  21 - 24  such as described above.  
         [0056]    For relative ease of alignment between each first signal generator  13  and each corresponding second signal generator  17 , for example, in replacement of input device  11 , it is preferable that first signal generator  13  of input device  11  and second signal generator  17  disposed on wiring board  16  function in noncontact combination, using, for example, magnetism or light.  
         [0057]    For example, a magnet is used as first signal generator  13  of input device  11 , while a magnetic sensor such as a Hall device is used as second signal generator  17  inside housing  14 . In this case, first and second signal generators  13 ,  17  function in noncontact relation, and a specified output is obtained from second signal generator  17 .  
         [0058]    In the above case, water-proof insulating sheet  37  can be disposed between first signal generators  13  of input device  11  and second signal generators  17  of housing  14  for protection from dust or water entering from opening  15  in which input device  11  is placed, input device  11  per se or others. Consequently, the electronic apparatus can have a dustproof and waterproof structure.  
         [0059]    Instead of having insulating sheet  37 , the electronic apparatus may have a wall, provided in the form of a box-shaped recessed part to cover the periphery and bottom of opening  15  of housing  14 , as a waterproof construction.  
         [0060]    By using a light-emitting device such as a LED or an EL device, for example, at wiring board  16  provided with second signal generators  17  inside housing  14  and using light-transmitting material for cover  19  to allow cover  19  to guide light emitted by the light-emitting device to the top side of housing  14 , the periphery of input device  11  can be illuminated with this light. This improves visibility of the position of input device  11  and allows favorable operation, for example, even at night.  
         [0061]    Not only cover  19  but also component case  12  of input device  11  may be made of light-transmitting material to guide the light emitted by the light-emitting device.  
         [0062]    As described above, the present embodiment facilitates the replacement of input device  11  which can be removed by just detaching cover  19  from housing  14  without removing housing  14  from the electronic apparatus.  
         [0063]    The present invention is applicable to cases where a stick, a pad, a rolling member or the like is mounted as operating member  11 A of input device  11 , and each first signal generator  13  operates in accordance with the operation of such operating member  11 A.  
         [0064]    (Exemplary Embodiment 2)  
         [0065]    The second exemplary embodiment of the present invention will be described hereinafter.  
         [0066]    In the present embodiment, a trackball device capable of detecting operation and a signal through use of magnetism is mounted in an electronic apparatus in place of input device  11  such as described in the first exemplary embodiment. Elements similar to those in the first embodiment have the same reference marks and will not described in detail.  
         [0067]    [0067]FIGS. 3 and 4 are an exploded perspective view and a sectional view, respectively, of the electronic apparatus in accordance with the second embodiment of the present invention. FIG. 5 is a top plan view of the same electronic apparatus from which a housing, and a case of the trackball device are omitted, and FIG. 6 is a sectional view taken along line A-A of FIG. 5. FIG. 7 is a top plan view of the same electronic apparatus from which the housing, the case of the trackball device, a ball, rollers and others are omitted.  
         [0068]    As shown in these drawings, the electronic apparatus of the present embodiment has trackball device  40  placed in opening  15  of housing  14  as input device  11 . Cover  19  is mounted and fixed to housing  14  from the upper side, so that trackball device  40  is positioned.  
         [0069]    First, a description will be provided of this trackball device  40 .  
         [0070]    As shown in FIGS. 4 and 5, XI roller  42  and XII roller  43  are disposed in opposed relation, and YI roller  44  and YII roller  45  are disposed in opposed relation. These rollers  42 - 45  each have the shape of a round shaft and are arranged in a square configuration in the vicinity of respective sides of a top surface of square base  41  molded out of resin, so that one pair of rollers is orthogonal to the other pair of rollers. Supports  46 - 49  formed integrally with base  41  rotatably support rollers  42 - 45 , respectively.  
         [0071]    Contact parts  42 A,  43 A,  44 A,  45 A provided at respective middle parts of XI roller  42 , XII roller  43 , YI roller  44  and YII roller  45  are in respective positions slightly lower than a center of ball (operating member)  50  of trackball device  40  and are positioned around ball  50  to each face ball  50  across an established clearance.  
         [0072]    Respective contact parts  42 A- 45 A of XI roller  42  to YII roller  45  are circular in section and have specific recessed and projected parts in respective equally divided positions in circumference.  
         [0073]    As shown in FIGS. 5 and 6, rollers  42 - 45  have, at their respective ends, magnets (first signal generators)  51 - 54  each magnetized with north and south poles alternating every 90°. These magnets  51 - 54  rotate in synchronization with respective rotating rollers  42 - 45 .  
         [0074]    As shown in FIGS. 3 and 4, case  55  of trackball device  40  is fixed on base  41  to form a component case in cooperation with base  41 . This case  55  is made of resin and has circular hole  55 A in the center of its top surface and peripheral wall  55 B extending downward from an outer edge of its top surface. Circular hole  55 A has a smaller diameter than ball  50  to allow an upper portion of ball  50  stored in case  55  to project, and a lower edge of peripheral wall  55 B is fixed to base  41 . Thus, trackball device  40  does not let go of ball  50  under normal conditions.  
         [0075]    As shown in FIG. 4, ball  50  is pushed from beneath by one end of resilient cantilever plate spring  56 , the other end of which is fixed into base  41  by insert molding or the like. When ball  50  is in such a normal condition as not to be operated, circular hole  55 A in the center of the top surface of case  55  is closed by the upper end portion of ball  50 .  
         [0076]    Ball  50  is vertically movable in a space defined by case  55  and base  41  since a lower end portion of ball  50  pushes plate spring  56  down when downward pressing force is applied to ball  50 .  
         [0077]    After trackball device  40  thus configured is placed in opening  15  of housing  14  as described earlier, cover  19  is mounted. Consequently, the component case (a combination of base  41  and case  55 ) is restricted sideways by a sidewall of each stepped part  15 D of housing  14  and sandwiched vertically between wiring board  57  disposed inside housing  14  and cover  19 , thereby being fixedly installed in the electronic apparatus.  
         [0078]    As shown in FIG. 6, magnetic sensors  58 - 61  are disposed on wiring board  57  inside housing  14  with their respective terminals  58 A- 61 A soldered to wiring board  57 . These magnetic sensors  58 - 61  are second signal generators functioning in combination with respective magnets (first signal generators)  5154  of trackball device  40  to output specified signals.  
         [0079]    Magnetic sensors  58 - 61  are provided in respective positions corresponding to respective magnets  51 - 54  attached to respective rollers  42 - 45  of trackball device  40 .  
         [0080]    These sensors  58 - 61  and a top side of wiring board  57  are collectively covered with flexible insulating sheet  62 .  
         [0081]    A central part of a configuration of magnetic sensors  58 - 61  arranged on wiring board  57  corresponds to the position of the lower end portion of ball  50  of trackball device  40 . Wiring board  57  is formed with, at this central part, self-restoring push switch  63 .  
         [0082]    This self-restoring push switch  63  includes outer fixed contact  64  formed of metallic foil or the like on wiring board  57 , domelike movable contact  65  formed of a convex, resilient metal sheet, and central fixed contact  66  provided on wiring board  57  below a central portion of movable contact  65 . Movable contact  65  and central fixed contact  66  face each other across an established space, and a top surface of movable contact  65  is covered with flexible insulating film  67  having an adhesive layer on its bottom surface.  
         [0083]    Push switch  63  having the above-described structure is low-profile and can be constructed at low cost. This push switch  63  also has high performance because switch  63  restores itself and has a click feel in operation.  
         [0084]    Domelike movable contact  65  has resilient restitutive force set equal to or greater than specified resilient restitutive force so as not to be turned inside out by being pressed by ball  50  when ball  50  is in normal condition or in rolling operation.  
         [0085]    It is not necessary for wiring board  57  to be formed with self-restoring push switch  63 . Switch  63  may be mounted to wiring board  57  as a completed low-profile single push switch.  
         [0086]    Referring to FIGS. 8 and 9, a description will be provided next of an operation of the electronic apparatus in accordance with the present embodiment.  
         [0087]    [0087]FIG. 8 is a sectional view taken along line X-X of FIG. 5, illustrating ball  50  of the trackball device in rolling operation, and FIG. 9 is a sectional view illustrating ball  50  in pressing operation.  
         [0088]    First, a description will be provided of a leftward rolling operation of ball  50  that follows the normal condition illustrated by FIGS. 4 and 6 in which trackball device (input device)  40  of the electronic apparatus of this embodiment is not in operation. The leftward rolling operation is rolling of ball  50  leftward, that is, in a direction indicated by an arrow of each one of FIGS. 6 and 8 with a hand or a finger touching the upper portion of ball (operating member)  50  projecting upward through circular hole  55 A of case  55  of trackball device  40 .  
         [0089]    When rolled leftward, ball  50  contacts only contact part  42 A of XI roller  42  positioned in the direction of the operation, or ball  50  contacts contact part  42 A of XI roller  42  and either contact part  44 A of YI roller  44  or contact part  45 A of YII roller  45  at the same time.  
         [0090]    Here, ball  50  rotates while contacting the recessed and projected parts provided at contact part  42 A of XI roller  42 , which is positioned in the direction of the operation, at right angles, thereby generating frictional force great enough to rotate XI roller  42 , and consequently, XI roller rotates.  
         [0091]    Even when ball  50  comes into contact with either contact part  44 A of YI roller  44  or contact part  45 A of YII roller  45  that is disposed along a direction orthogonal to the direction of the operation, ball  50  contacts the recessed and projected parts of contact part  44 A or  45 A in a substantially horizontal direction, so that any one of YI roller  44  and YII roller  45  is not provided with enough frictional force for rotation. Consequently, ball  50  runs idle, and YI roller  44  and YII roller  45  do not rotate.  
         [0092]    As XI roller  42  rotates, magnet (first signal generator)  51  provided at the end of roller  42  rotates accordingly, and the north and south poles of magnet  51  alternately and repeatedly approach corresponding magnetic sensor (second signal generator)  58  disposed below magnet  51  on wiring board  57 .  
         [0093]    As the north pole of magnet  51  approaches magnetic sensor  58 , magnetism of the north pole that acts on magnetic sensor  58  increases accordingly, and sensor  58  produces a larger positive output voltage accordingly.  
         [0094]    As the south pole approaches sensor  58 , magnetism of the south pole that acts on sensor  58  increases accordingly, and sensor  58  produces a larger negative output voltage accordingly.  
         [0095]    In other words, when the output voltage from terminal  58 A of magnetic sensor  58  exceeds a specified value, an ON state is established, and an OFF state is established when the output voltage is at or below the specified value. A corresponding signal is processed by a microcomputer (not shown) or the like for generation of a digital signal.  
         [0096]    This allows determination of the number of revolutions of XI roller  42 , and based on the number of revolutions, the amount of movement of a cursor or the like, which is displayed on a display screen of the electronic apparatus, in a positive or negative direction on the x-axis is determined.  
         [0097]    When ball  50  is rolled rightward, XI roller  42  does not rotate, but XII roller  43  rotates, and the amount of movement of the cursor, displayed on the screen, in a direction opposite to the above-mentioned leftward rolling operation on the x-axis is determined. When ball  50  is rolled forward or backward in the drawing, XI roller  42  and XII roller  43  do not rotate, but opposed YI roller  44  and YII roller  45  rotate, and the amount of movement in a positive or negative direction on the y-axis is determined.  
         [0098]    When ball  50  is rolled diagonally in the drawing, one of XI roller  42  and XII roller  43  and one of YI roller  44  and YII roller  45  rotate, and the amount of movement of the cursor in the specified direction defined by the x- and y-axes is determined based on the rolling direction and components of ball  50 .  
         [0099]    In the above description, magnets  51 - 54  of XI roller  42  to YII roller  45  of trackball device  40  are each magnetized with the north and south poles alternating every 90°. This means that the signal is produced twice during one rotation of each one of rollers  42 - 45 . However, the number of times the signal is produced may be increased or decreased on as a needed basis.  
         [0100]    When the upper portion of ball  50  is pressed with the finger or the like in the normal condition (illustrated by FIG. 4) after the arrival of the cursor in a desired position on the display screen through the rolling operation of ball  50 , ball  50  pushes down plate spring  56 , disposed below ball  50 , as shown in FIG. 9. Consequently, projection  56 A of plate spring  56  presses, at its bottom surface, a central portion of the top part of push switch  63 , that is, the central portion of domelike movable contact  65  downward via insulating sheet  62 .  
         [0101]    When this downward pressing force exceeds a specified value, domelike movable contact  65  is resiliently turned inside out with the click feel. Here, a bottom surface of the central portion of movable contact  65  contacts central fixed contact  66  as shown in FIG. 9, whereby conduction is established between outer and central fixed contacts  64 ,  66  through movable contact  65 .  
         [0102]    Here, a signal is transmitted as a signal identifying the position of the cursor on the display screen to a circuit of the electronic apparatus mounted with trackball device  40  through a circuit (not shown) on wiring board  57 .  
         [0103]    When the downward pressing force applied to ball  50  is released, domelike movable contact  65  restores its original domelike shape by its own resilient restoring force and pushes ball  50  back from beneath insulating sheet  62  and projection  56 A of plate spring  56 . Consequently, outer and central fixed contacts  64 ,  66  of push switch  63  are electrically disconnected from each other.  
         [0104]    In addition, ball  50  is pushed up until it is urged against circular hole  55 A of case  55  by the restoring force of cantilever plate spring  56 , thus returning to the normal condition illustrated by FIG. 4.  
         [0105]    Insulating sheet  62  may have a domelike portion corresponding to push switch  63  to function in place of plate spring  56 . In this case, the domelike portion urges ball  50  upward by contacting the lower end portion of ball  50 , thereby closing circular hole  55 A of case  55 .  
         [0106]    According to the present embodiment described above, the cursor displayed on the screen can be moved easily with high definition through the rolling operation of ball  50 , and the signal identifying the position of the cursor can be produced by operating push switch  63 , positioned below ball  50 , through the pressing operation of ball  50 . The obtained electronic apparatus equipped with the push switch and the trackball device thus operates stably and allows a small projected area.  
         [0107]    Even this embodiment eliminates the need to open housing  14  for removal of wiring board  57 , thereby facilitating the replacement of trackball device  40  when, for example, a structurally operating part of trackball device  40  has failed. The present embodiment is also similar to the first embodiment in that the electronic apparatus has a dustproof and waterproof structure since magnetic sensors  58 - 61  and the top side of wiring board  57  are collectively covered with waterproof insulating sheet  62 .  
         [0108]    (Exemplary Embodiment 3)  
         [0109]    The third exemplary embodiment of the present invention will be described hereinafter.  
         [0110]    As in the case with the electronic apparatus of the second exemplary embodiment, an electronic apparatus of the present embodiment is equipped with magnetic trackball device  40  as an input device. In this embodiment, second signal generators differ from those of the second embodiment, and the description deals mainly with these second signal generators.  
         [0111]    Elements (e.g., elements of trackball device  40 ) similar to those in the first and second embodiments have the same reference marks and will not be described in detail.  
         [0112]    [0112]FIG. 10 is a top plan view of the electronic apparatus, from which a housing, a case of the trackball device, a ball and rollers are omitted, in accordance with the third embodiment of the present invention.  
         [0113]    As shown in this drawing, the present embodiment differs structurally from the second embodiment illustrated by FIG. 7 in that the second signal generators mounted on wiring board  57  are four reed switches  71 - 74 .  
         [0114]    These four reed switches  71 - 74  are disposed on wiring board  57  of the electronic apparatus with their respective terminals  71 A- 74 A soldered to board  57 . As in the case of the second embodiment, these second signal generators are provided in respective positions corresponding to respective magnets (first signal generators)  51 - 54  (not shown in FIG. 10) attached to respective XI roller  42  to YII roller  45  (not shown in FIG. 10) rotatably supported by base  41 .  
         [0115]    As north and south poles of magnets  51 - 54  mounted to respective rollers  42 - 45  change their positions relative to each other through rotations of rollers  42 - 45 , reed switches  71 - 74  repeatedly switch back and forth between ON and OFF accordingly. In this way, reed switches  71 - 74  output digital signals.  
         [0116]    Except for the reed switches, the structure of the present embodiment is similar to that of the second embodiment and will not be described.  
         [0117]    Next, a description will be provided of an operation of the thus-configured electronic apparatus in accordance with the present embodiment.  
         [0118]    When ball  50  of trackball device  40  is rolled leftward, XI roller  42  positioned in the rolling direction of ball  50  rotates as in the case of the second embodiment. Accordingly, magnet (first signal generator)  51  rotates, and its north and south poles alternately and repeatedly approach corresponding reed switch (second signal generator)  71  as in the case of the second embodiment.  
         [0119]    When the north pole or the south pole of magnet  51  are in a specified region with respect to reed switch  71 , reed switch  71  is in the ON state, and switch  71  changes to the OFF state when the north and south poles deviate from the specified region. Reed switch  71  thus produces the digital signal corresponding to the rotation of magnet  51 .  
         [0120]    In this way, the number of revolutions of roller  42 , that is, the amount of movement of a cursor, displayed on a display screen of the electronic apparatus including trackball device  40 , in the specified direction is determined. This is similar to the case of the second embodiment.  
         [0121]    Even in cases where ball  50  is rolled in a different direction, a similar operation takes place, and the reed switch corresponding to the direction of the operation produces the digital signal.  
         [0122]    In the present embodiment, the electronic apparatus operates similarly to that of the second embodiment when ball  50  of trackball device  50  is pressed, and trackball device  40  is mounted in a manner similar to that of the second embodiment, so that their descriptions are omitted.  
         [0123]    According to the present embodiment described above, reed switches  7174  are disposed as the second signal generators, so that each of their outputs can be obtained in the form of the digital signal. Thus, the electronic apparatus does not require an A/D conversion circuit for processing a signal and has simplified circuitry.  
         [0124]    (Exemplary Embodiment 4)  
         [0125]    The fourth exemplary embodiment of the present invention will be described hereinafter.  
         [0126]    In an electronic apparatus of the present embodiment, a part where input device  11  is mounted differs in structure from that of the first embodiment, and the description deals mainly with this part, referring to the accompanying drawings.  
         [0127]    [0127]FIG. 11 is a perspective view of an essential part of the electronic apparatus in accordance with the fourth embodiment of the present invention, and FIG. 12 is an exploded perspective view of the same electronic apparatus. FIG. 13 is a sectional view taken along line B-B of FIG. 12, illustrating the electronic apparatus in complete condition.  
         [0128]    As shown in these drawings, the electronic apparatus of the present embodiment utilizes housing  81  per se for positioning and mounting input device  11 .  
         [0129]    In other words, the structure of the present embodiment does not include cover  19  (see FIG. 1) such as described in the first embodiment. This allows the reduced number of parts.  
         [0130]    As shown in FIGS. 11 and 12, housing  81  has opening  81 A which is provided in place to correspond to operating member  11 A of input device  11 , and in the vicinity of opening  81 A, locating recess  81 B corresponding to the shape of an upper part of component case  12  of input device  11  is provided in a reverse side of housing  81 .  
         [0131]    Although elements such as other operating members are not shown in the drawings, housing  81  is provided with those elements on its side having opening  81 A. In other words, the side of housing  81  that faces operating member  11 A of input device  11  defines a main operating surface of the electronic apparatus.  
         [0132]    On wiring board  16  disposed inside housing  81 , second signal generators  17  are disposed in respective positions corresponding to opening  81 A and recess  81 B by soldering or the like.  
         [0133]    Each one of second signal generators  17  produces a specified output signal by functioning in noncontact combination with each corresponding first signal generator (not shown) provided inside input device  11 .  
         [0134]    Although elements such as other electronic parts are not shown in the drawings, those elements are mounted on wiring board  16  with second signal generators  17 , and those elements, second signal generators  17  and a top side of board  16  are collectively covered with insulating sheet  37 .  
         [0135]    Thus, wiring board  16  and those elements, such as second signal generators  17  and other electronic devices, which are mounted on board  16 , can be protected without fail from dust or water entering from opening  81 A of housing  81  or holes or slits, formed for other operating members in the side having opening  81 A.  
         [0136]    Input device  11  is positioned and mounted by being sandwiched between recess  81 B of housing  81  and insulating sheet  37  covering wiring board  16  after its operating member  1 A is inserted through opening  81 A of housing  81 . Since the upper part of component case  12  of input device  11  is inserted in recess  81 B, case  12  and recess  81 B engage sideways with each other, whereby input device  11  is positioned in a direction parallel to wiring board  16 . Moreover, input device  11  is positioned vertically because a top surface of case  12  is pressed down by the reverse side of housing  81  at recess  81 B, while a bottom surface of case  12  is supported by insulating sheet  37  over wiring board  16 .  
         [0137]    Rattle or the like produced by input device  11  can be reduced if soft insulting sheet  37  is used and pressed slightly along its thickness by the bottom surface of case  12  in installation. Input device  11  thus obtained is of high quality.  
         [0138]    As mentioned above, the electronic apparatus of the present embodiment has the reduced number of elements, and the part of input device  11  that includes operating member  11 A can be removed for replacement by just opening housing  81 .  
         [0139]    In the present embodiment, an operation and others of input device  11  are similar to those described in the first embodiment and will not be described.  
         [0140]    In this embodiment, housing  81  has been utilized to hold input device  11  down. However, input device  11  may be positioned and mounted by use of another member.  
         [0141]    Input device  11  using the first signal generators in noncontact condition for operation is not limited to a stick type input device such as described above. For example, the input device may be trackball device  40  such as described in the second embodiment, or may use a rolling member such as a ball or a roller as the operating member or a pad for specified input operation.  
         [0142]    The present invention&#39;s structure for mounting the input device is also applicable to elements other than input device  11 .  
       INDUSTRIAL APPLICABILITY  
       [0143]    An electronic apparatus of the present invention that includes an input device has first signal generators disposed inside the input device, and second signal generators disposed in a housing, and these second signal generators function in combination with the first signal generators, respectively. The replacement of the input device is easy because it does not require removal of a wiring board disposed inside the housing, and the electronic apparatus is excellently maintainable and has excellent reliability.  
         [0144]    The first and second signal generators operate in noncontact relation. This facilitates improvement of the apparatus&#39;s resistance to dust and water.  
         [0145]    The use of a trackball device as the input device allows fine input operation such as selecting, deciding on or confirming a required operation. Since an output from each one of the second signal generators can be obtained in the form of a digital signal, the electronic apparatus can have simplified circuitry and is inexpensive and easy to use.