Abstract:
[Problems] To provide a position sensor small enough to be contained in a groove formed in an air cylinder in which minimum stroke for fixing and differential travel are improved. 
     [Means for Solving Problems] The position sensor comprises a Hall IC ( 50 ) for turning an electric signal on/off according to the position relative to a magnet provided on the piston of an air cylinder, a resin ( 60 ) such as a polyamide resin molded to cover the Hall IC ( 50 ), a stainless steel frame ( 30 ) defining the orientation and position of the Hall IC ( 50 ) in the resin ( 60 ), a part ( 40 ) fixed to the frame ( 30 ) in order to pass a screw for fixing the position sensor ( 1 ) to the air cylinder, conductors ( 18, 20, 22 ) connected to terminals ( 24, 26, 28 ) of the Hall IC ( 50 ) by soldering, rubber insulators ( 12, 14, 16 ) covering the conductors ( 18, 20, 22 ), and a rubber sheath part ( 10 ) for bundling the insulators ( 12, 14, 16 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a device and system for detecting position of a piston and others in a cylinder. 
       BACKGROUND ART 
       [0002]    Conventionally, to control position of a piston in an air cylinder, position detecting device has been mounted on the side of air cylinder body such that when the piston is displaced, the position can be detected. Non-patent document 1 shows state where a contact-type sensor and a non-contact-type sensor are mounted on an air cylinder as the above detecting device. 
         [0003]      FIGS. 8 and 9  are perspective views of the contact-type sensor, the non-contact-type sensor and the air cylinder described in the non-patent document 1. The contact-type sensor consists of magnetoresistive element. 
         [0004]      FIG. 8  shows way how contact-type sensor  200  is mounted on air cylinder  120 . In particular, approximately cylindrical contact-type sensor  200  is inserted into groove  130  formed on the side of the body of the air cylinder  120 . Contact-type sensor  200  is mounted on the air cylinder  120  with setscrew  210  using screwdriver  220 . 
         [0005]      FIG. 9  shows way how the non-contact-type sensor  300  is mounted on the air cylinder  120 . In particular, nut  310  is inserted into the groove  130  formed on the side of the body of the air cylinder  120 . Mounting screw  330  is screwed through screw installing section  340  on the side of non-contact-type sensor  30  and spacer  320 , to nut  310 . 
         [0006]    Here, a magnet, placed such that moving direction and magnetic pole direction are parallel, is generally provided on the piston  110  provided in the body of the air cylinder  120 . The conventional position detecting device detects position of the piston  110  using this magnet and the sensor  200  or the sensor  300 . 
         [0007]    In addition, according to the non-patent document 2, mountable minimum stroke of the contact-type sensor  200  is approximately 10 mm and mountable minimum stroke of the non-contact-type sensor  300  is approximately 5 mm. Furthermore, hysterisis of the sensor  200  is approximately 1.5 mm and hysterisis of the non-contact-type sensor  300  is approximately 1 mm. 
         [0000]    Non-patent document 1: SMC Corporation catalog Best Pneumatics 2 page 175
 
Non-patent document 2: SMC Corporation catalog Best Pneumatics 2 page 561
 
       DISCLOSURE OF INVENTION 
     Problem to be Solved by the Invention 
       [0008]    However, conventional contact-type sensor is not preferable with respect to its mountable minimum stroke and hysteresis, even though it is relatively small. On the other hand, non-contact-type sensor is relatively preferable with respect to mountable minimum stroke and hysterisis, although it is large. These sensors have a trade-off relation between size and mountable minimum stroke and hysterisis. 
         [0009]    Therefore, for example, in case the operation of the air cylinder needs to be controlled with accuracy, non-contact-type sensor should be used. However, the non-contact-type sensor is relatively preferred with respect to mountable minimum stroke and hysterisis, though it is large. Consequently, it occupies large space. It is necessary to provide screw installing section on non-contact-type sensor. It is necessary to mount non-contact-type sensor on air cylinder using both screw and nut. 
         [0010]    Therefore, the purpose of the present invention is to improve mountable minimum stroke and hysterisis, and, to provide a position detecting device small enough to be contained in a groove formed on an air cylinder. 
       Means for Solving the Problem 
       [0011]    To solve the problem above, the position detecting device in the present invention is provided with
       first section comprising magnetic body wherein moving direction and boundary of magnetic pole is placed perpendicularly,   member including said first section and second section which is relatively displaced and   position detecting device detecting relative position,
 
the position detecting device comprising
   Hall IC which switches on/off electrical signal output depending on the relative position to the magnetic body, and   resin covering said Hall IC while positioning it inside,
 
and being mounted such that the switching point of on/off electrical signal output crosses the boundary of the magnetic pole after relative displacement of the first section.
       
 
         [0017]    The position detecting device is provided with Hall IC instead of a conventional reed switch and a magnetoresistive element. Hall ICs are superior with respect to magnetic sensitivity, and most of them are small in size. If the Hall IC is set on required direction and position in the position detecting device, it will become possible to detect the position of a piston only by mounting the position detecting device in the manner shown in  FIG. 8 . 
         [0018]    A cavity for containing the Hall IC may be formed in the resin, or, a frame for positioning the Hall IC inside it may be provided in the resin. In case a frame being provided, it is necessary to prevent it from moving from the predetermined position until the resin hardens. So, it is better to form a positioning section which has contact with the inner wall of the mold for covering Hall IC with resin, or, which is able to be nipped between male and female molds. In addition, an opening is formed on the frame near the terminal of Hall IC, which increases validity of insulation of terminal and frame. Furthermore, a through opening is formed to pass resin which is not hardened yet. In this way, by ensuring resin to go around both sides of the frame, sealing of resin and productivity of position detecting device is improved. In particular, by forming the through opening at the end of the frame, the periphery of the through opening will be the positioning section, so the productivity of the position detecting device will increase in that the through opening and positioning section can be formed in one process. 
         [0019]    This mounting section includes groove, hole, depression and flat part. In case of using a flat part, adhesive may be used for adhering. In addition, the above member includes automobile, elevator, nursing-care equipment, home security system, cellular phone handset, disconnection detecting system, industrial robot and so on, besides a device wherein the first section is a piston in a cylinder. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]      FIG. 1(   a ) is a cross section view of position detecting device  1  of the embodiment of the present invention.  FIG. 1  ( b ) is a plane view of  FIG. 1  ( a ). The position detecting device  1  detects position of a piston. Air cylinder is generally provided with a magnet in a piston, so that the position of a piston can be detected by means of the magnet and Hall IC provided in the position detecting device  1 . 
         [0021]      FIG. 1  shows
       Hall IC  10  (for example, Product No. EW-462 (Asahi Kasei Electronics)) switching on/off electrical signals depending on relative position to a magnet provided in a piston in the air cylinder,   resin  60  covering the Hall IC  50  such as nylon type polyamide resin including hot-melt which is mold formed or others,   stainless frame  30  specifying direction and position of the Hall IC  50  in the resin  60  and   screw installing section  40 , mounted on the frame  30 , for installing screw (not shown) for mounting the position detecting device  1  on the air cylinder.         
         [0026]    Furthermore,  FIG. 1  shows
       conductor  18 ,  20  and  22  connected to terminal  24 ,  26  and  28  of the Hall IC  50  by soldering or others,   rubber insulator  12 ,  14  and  16  coating the conductor  18 ,  20  and  22  and   rubber sheath section  10  including rubber insulators  12 ,  14  and  16 .
 
As described later, LED and others for informing on-state of the Hall IC  50  can be provided on the position detecting device  1 .
       
 
         [0030]    Here, the Hall IC  50  is an approximately rectangular solid, for example, with 3.0±0.1 mm body length in the horizontal direction in  FIG. 1  ( b ), 3.6±0.1 mm body width in the vertical direction in  FIG. 1  ( b ) and 1.2±0.1 mm thickness (vertical direction in  FIG. 1  ( c )). Resin  60  has, for example, a diameter of 3.9 φ and length of 1.5 cm. Screw installing section  40  has, for example, a base with 3 φ outside diameter, an upper surface with 2.3 φ outside diameter and 2 φ inside diameter. Sheath section  10  is 2.8 φ. 
         [0031]    A groove with a diameter of approximately 4.0 φ-4.2 φ and an integrally formed opening close to said groove are formed on the side of the air cylinder in the long side direction in general. Position detecting device  1  in the present invention has a diameter of, for example, 3.9 φ, which is able to be mounted in this groove. 
         [0032]      FIG. 2  is a detailed view of the frame  30  shown in  FIG. 1 .  FIG. 2  ( a ) is a side view of the long side direction of the frame  30 ,  FIG. 2  ( b ) is a plane view of the frame  30  and  FIG. 2  ( c ) is a side view of the short side direction of the frame  30 .
       Approximately elliptic opening  38  placed near terminal  28  of the Hall IC  50 ,   round through hole  37  provided close to the opening  38 , where the screw installing section  40  can be mounted,   rectangular passing section  32  provided on one end of the frame  30 , where the resin  60  passes before hardening,   positioning sections  33  and  35 , placed on both sides of passing section  32 , in contact with the inner wall of mold (not shown) and   grippers  39 ,  34  and  36 , respectively provided near the other end and the opening  38  of the frame  30 , which position the horizontal direction of Hall IC  1  in  FIG. 2  ( b ) are formed on the frame  30 .         
         [0038]    Opening  38  ensures insulation of terminal  28  and the frame  30  when terminal  28  and the conductor  22  are solder connected. By forming through hole  37  combined with the screw installing section  40 , the position detecting device  1  will able to be mounted on the air cylinder with a screw. The screw installing section  40  and through hole  37  is connected by, for example, laser welding. 
         [0039]    By forming passing section  32 , the resin  60  before hardening is ensured to go around both sides of the frame  30 , the resin  60  is able to be mold-formed efficiently and productivity of the position detecting device  1  increases. The Hall IC  50  is gripped between sides of grippers  34  and  36  on gripper  39  side and inside of the gripper  39 . The gripper  39  is bent 83-85 degrees to the frame body so as to grip the Hall IC, which create springiness. Adhesive may be applied between the frame  30  and the Hall IC to specify the vertical position of the Hall IC  50  on the frame  30  in  FIG. 2(   b ). 
         [0040]    Positioning sections  33  and  35  may be formed, for example, on the base of the frame. Furthermore, direction and position of the Hall IC  50  may be provided by a projection formed in the screw installing section  40  in mold, with positioning section  33  and  35 . 
         [0041]    Here, the body of the frame  30  is, for example, 9.48 mm in the long side direction, 3.2 mm in the short side direction and 0.2 mm in thickness. The diameter of through hole  37  is 2.3 φ. Opening  38  is 2.4 mm in the long side direction and 1.2 mm in the short side direction. Passing section  32  is 0.4 mm×3.1 mm. Gripper  39  is 1.4 mm in height×1 mm in width. Grippers  36  and  38  are 1.4 mm in height×0.7 mm in width. Positioning sections  33  and  35  are 0.5 mm in width×0.4 mm in length. 
         [0042]    Each of the above dimensions of the frame  30  depend on shape and size of the Hall IC  50 , mounting position (for example, groove on the side of the air cylinder) of the position detection device  1 , and so on. Those dimensions are not limited to the above-mentioned amounts. 
         [0043]    In addition, direction of the Hall IC  50  is, for example, sensor section  52  ( FIG. 6 ) of the Hall IC  50  is placed in a direction perpendicular to the long length direction of the position detecting device  1 . In this case, the Hall IC  50  may be faced either up or down. Placed in this direction, for example, setting is completed only by inserting the position detecting device  1  into the groove on the side of piston and fixing it with screw or others. Direction of magnetic poles of magnet and moving direction of the piston is the same in general. Furthermore, north pole is placed on the side where the air cylinder is stretched and south pole is placed on the side where the air cylinder is compressed. 
         [0044]      FIG. 3  shows an example deformation of the resin  60  of the position detecting device  1  shown in  FIG. 1 .  FIG. 3  ( a ) is a side view of the resin  60  in the long side direction,  FIG. 3  ( b ) is a plane view of the resin  60  and  FIG. 3  ( c ) is a side view of the resin  60  in the short side direction. Same parts are assigned with the same signs in  FIG. 1  and  FIG. 3 . 
         [0045]    The resin  60 , for example, polyamide resin containing approximately 10-30% of glass fiber is polybutylene terephthalate (PBT) resin, which provide strength. Screw installing section  40  is formed on the resin  60 , as shown in  FIG. 1 . 
         [0046]    As shown in  FIG. 3  ( a ), cavity  62  for containing the Hall IC  50  is formed close to the screw installing section  40 . The cavity  62  containing the Hall IC  50  and little space has the shape of approximately rectangular solid. Resin  60  shown in  FIG. 3  and  FIG. 4  is smaller than the Hall IC  50  of the already described size. Approximately 3.0 mm length already described is reduced to approximately 2.2 mm, approximately 3.6 mm width to approximately 3.3 mm and approximately 1.2 mm thickness to approximately 1.0 mm in particular. 
         [0047]    As shown in  FIG. 3  ( a ) and  FIG. 3  ( c ), cavity  64  and recess  66  to contain the conductor  22  are formed from the upper side to the lower side of the cavity  62 . Cavity  64  and the recess  66  have the shape of approximately rectangular solid here, though they may have the shape of approximately semicircle. 
         [0048]    A pair of holding piece  70  is formed near the cavity  64  and the recess  66  at the end of cavities  62  and  64 . The holding piece  70  includes insulator holder  66  holding insulator  12 ,  14  and  16  and sheath section holder  68  holding the sheath section  10 . Long side cross-section of the resin  60  of the insulator holder  66  has the shape of approximately semicircle. Long side cross-section of the resin  60  of sheath section holder  68  has a rainbow shape. 
         [0049]    Marking section  72 , one of which shows south pole and another of which shows north pole, is formed between the holding piece  70  and the screw installing section  40 . The marking section  72  makes it easier for users to view which direction the position detecting device  1  should be set on the groove on the cylinder when using the position detecting device  1 . 
         [0050]    Here is the production process of the position detecting device  1  using the resin  60 . First, conductors  18 ,  20  and  22  are connected to terminals  24 ,  26  and  28  on the Hall IC  50  by soldering or others. Then, according to the mark of the marking section  72 , the Hall IC  50  is set in the direction and inserted into the cavity  62  of the resin  60 . 
         [0051]    Consequently, the Hall IC  50  is contained and positioned in the cavity  62 . In addition, the conductor  22  and the insulator  16  are contained in the cavity  64 . Furthermore, insulators  12 ,  14  and  16  are held at insulator holder  66  of the holding piece  70  and the sheath section  10  is held at sheath section holder  68 . Then, space between the holding piece  70  and around it is covered with hot-melt resin such as polyamide resin not including glass fiber. Position detecting device  1  is thus produced. 
         [0052]      FIG. 4  shows another example using different type of resin  60 .  FIG. 4  ( a ) is a side view of the resin  60  in the long side direction,  FIG. 4  ( b ) is a plane view of the resin  60 ,  FIG. 4  ( c ) is a base view of the resin  60  and  FIG. 4  ( d ) is a side view of the resin  60  in the short side direction. Same parts are assigned with the same signs in  FIG. 1  and  FIG. 4 . 
         [0053]    The position detecting device  1  is not equal to that in  FIG. 3 , being provided with the LED  80  which emits light when electrical signal outputted from the Hall IC  50  is on-state. The resin  60  is also polyamide resin containing approximately 10-30% of glass fiber, polybutylene terephthalate (PBT) resin. Upper part of the cavity  62  in  FIG. 4  ( a ) is cut off, compared to that in  FIG. 3  ( a ). The conductor  22  passes through this cut-off part. 
         [0054]    Here, the holding piece  70  is U-shaped as shown in  FIG. 4  ( d ). As shown in  FIG. 4  ( b ), notch  74  for passing conductor connecting, for example, positive terminal and output terminal on the Hall IC  50  and the LED  80 , is formed on the holding piece  70 . 
         [0055]    As shown in  FIG. 4  ( c ), the LED  80  and resistor  82  can be mounted on the base of the position detecting device  1  dose to notch  74 . The LED  80  and the resistor  82  are electrically connected in series each other. The LED  80  and the resistor  82  are chip-shaped to reduce size and weight. 
         [0056]    Marking section  72  showing whether the position detecting device  1  is for south pole/north pole is formed between the holding piece  70  and the screw installing section  40 . Here, the resin  60  shown in  FIG. 3  is able to fix, even if the marking section  72  showing south pole in the groove  130  of the air cylinder is on the opening side of the groove  130 , or, if the marking section  72  showing north pole is on the opening side of the groove  130 , because the outline of the resin  60  is approximately cylinder. However, the resin  60  shown in  FIG. 4  is provided with the LED  80 , so it is necessary to place this part in the opening of the groove  130 . Therefore, in the production process of the position detecting device  1 , whether it is for north pole/for south pole is uniquely determined by the direction of the Hall IC  50  set in the cavity  62 . 
         [0057]      FIG. 5  is a typical diagram of member  91  of indicator light body  90  suited to using the resin  60  shown in  FIG. 3  or others.  FIG. 5  ( a ) is a side view of the long side direction of member  91  of the indicator light body  90 .  FIG. 5  ( b ) is a base view of member  91  of the indicator light body  90  and  FIG. 5  ( c ) is a side view of the short side direction of member  91  of the indicator light body  90 . Same parts are assigned with the same signs in  FIG. 5  and  FIG. 4  or other figures. 
         [0058]    This kind of indicator light is effective, for example, when LED cannot be set on the position detecting device  1  because of the size of the groove  130  of the air cylinder or others. In addition, this is effective when it is difficult to see mounting position of the position detecting device  1 . 
         [0059]    Here, member  91  of the indicator light body  90  shown in the figure is covered by resin. This resin has, for example, a plane base and an arch-like cross-section perpendicular to the long side direction. In the present embodiment, this resin is a mixture of black hot-melt and transparent hot-melt at the rate of, for example, 1:2-2:1. This kind of resin is blackish translucent. That is to say, black hot-melt serves as a diffuser. 
         [0060]    In this case, assuming that the LED  80  is a red LED, emitted light diffuses inside translucent hot-melt. Consequently, emission of the LED  80  was visible when indicator light was viewed from the horizontal direction. 
         [0061]    Emission color of the LED  80  and hot-melt color are not limited to the above case, and blue LED or green LED, or, yellow hot-melt including buff yellow one or white hot-melt can be used. In particular, emission color of the LED  80  and hot-melt color should be complementary colors or colors dose to them. 
         [0062]    As shown in  FIG. 5  ( a ), the LED  80  and the resistor  82  are placed on the upper surface of member  91  of indicator light. These are electrically series-connected by soldering or others. Each of the other end of indicator light  80  and the resistor  82  are respectively connected to notch contacts  84  and  86  by soldering or others. 
         [0063]    Notch section is placed in the lower part of the notch contacts  84  and  86 . The lower end of the notch section is wide, though the other parts are approximately half of the dimensions of the inside diameters of insulator  12 ,  14  and  16 , that is, approximately half of the dimensions of the outside diameters of the conductor  18 , and  22 . Consequently, by pressing the conductor  18  and others covered with insulator  12  and others into notch section, insulator  12  and others are disconnected by notch section, the notch contact  84  and others, the conductor  18  and others come in contact with each other and these are electrically connected. In this case, the conductor is pressed by notch section which is smaller than the outside diameter of conductor and deformed longer and thinner. In this way, using the above notch contact  84  and  86 , the notch contact  84  and others and the conductor  18  and others are electrically connected without a process where the insulator  12  is cut by a nipper or others. 
         [0064]    In addition, as shown in  FIG. 5  ( c ), an arch-like sheath holder  92  for holding sheath  10  is formed on member  91  of the indicator light. The sheath  10  is gripped by sheath holder  92  as shown in  FIG. 5  ( b ). Here, prior to said gripping, the sheath  10  itself is divided and the divided part is placed between the sheath holder  92 . In this way, as stated above, the notch contact  84  and others and the conductor  18  and others are electrically connected. 
         [0065]      FIG. 6  is a typical diagram of position detecting system  100  including the position detecting device  1  shown in  FIG. 1  and others. Position detecting system  100  shows the position detecting device  1 , the piston  110  which is the first section and the body of the air cylinder  120  which is the second section including the piston  110 . 
         [0066]    Groove  130 , where the position detecting device  1  is mounted, is formed on the body of the air cylinder  120 . A hole or a depression may be formed instead of the groove  130 . Furthermore, the position detecting device  1  may be adhered on the body of the air cylinder  120  with adhesive or others. 
         [0067]    Here is the production process of the position detecting system. First, the position detecting device  1  is inserted into the groove  130  formed on the side of the body of the air cylinder  120 . Then, the setscrew  150  is installed into the screw installing section  40  provided on the position detecting device  1  using screwdriver  160 . In this way, tip of the setscrew  150  hits the base opposing to the opening of the groove  130 , the position detecting device  1  body is pressed by the inner wall close to the opening of the groove  130  and mounted on the body of the air cylinder  120 . 
         [0068]      FIG. 7  is a principle explanatory diagram of position detecting in position detecting system  100 .  FIG. 7  ( a ) shows the magnet  140  provided on the piston  110  before displacement and  FIG. 7  ( b ) shows the magnet  140  after displacement. Magnet  140  is displaceable in the magnetic pole direction and set such that the boundary of north and south poles crosses the sensor section  52  of the Hall IC  50  after displacement. The sensor section  52  is a switching point of on/off electrical signal output of the Hall IC  50 . 
         [0069]    There is magnetic field line  140   b  around the magnet  140  connecting south pole and north pole with a curved line. In addition, there are isodynamic lines  140   c - 140   e  around the magnet  140  where magnetic force passes the same point. Each isodynamic lines  140   c - 140   e  and each magnetic field line  140   b  cross each other at right angles. Isodynamic line  140   d  is, for example, 0 gauss and isodynamic line  140   c  and  140   e  are, for example, respectively 25 gauss. Departing from the boundary of south and north poles of the magnet  140  to each magnetic pole, intensity of magnetic force of isodynamic lines increases in general. 
         [0070]    As shown in  FIG. 7  ( a ), before displacement of the magnet  140 , isodynamic side  140   d  is placed on the lower side of the sensor section  52  of the Hall IC  50 . In this case, the Hall IC  50  is off-state and electrical signal from the Hall IC turns off. 
         [0071]    At the same time, as shown in  FIG. 7  ( b ), after displacement of the magnet  140 , isodynamic side  140   d  is placed on the upper side of the sensor section  52  in the Hall IC  50 . In this case, the Hall IC  50  is on-state and electrical signal from the Hall IC turns on. Then, when the magnet  140  returns to the state before displacement, electrical signal switches off again. 
         [0072]    When the direction of the Hall IC  50  is reversed, electrical signal from the Hall IC  50  turns on as shown in  FIG. 7  ( a ) and electrical signal from the Hall IC  50  turns off as shown in  FIG. 7  ( b ). 
         [0073]    According to our experiment by blowing air to the body of the air cylinder  120  and moving the piston  110  with the position detecting device  1  mounted on the body of the air cylinder  120 , the mountable minimum stroke of the position detecting device  1  was found to be within 1 mm. As described above, the mountable minimum stroke of the conventional contact-type detecting device is approximately 10 mm and the mountable minimum stroke of the non-contact-type detecting device is approximately 5 mm. Furthermore, when moving the piston  110  to the position where the Hall IC  50  is turned on and bringing the piston  110  back to the position where Hall IC is turned off, hysterisis was approximately 0.1 mm. As described above, the conventional contact-type detecting device has a hysterisis of approximately 1.5 mm and the non-contact-type detecting device has a hysterisis of approximately 1 mm. In this way, the position detecting device  1  was dramatically improved in sensitivity compared to the conventional detecting device. 
         [0074]    In the present embodiments, mounting the position detecting device  1  on the body of the air cylinder  120  was taken as an example, but it should be noted that the position detecting device  1  can be mounted on an automobile, an elevator, a nursing-care equipment, a home security system, a cellular phone handset including folding type one, a disconnection detecting system, an industrial robot and so on provided with a magnet or with a built-in magnet. 
         [0075]    The present invention may be applied not only to examples explained in embodiments 7 and 8 but also to the following examples:
       a door switch which detects opening/closing of an automobile door   an elevator system which controls stop positions of an elevator   a position control system of an arm which controls the position of robot arms and others of industrial machines or nursing devices   a disconnection detection system which detects the disconnection of piano wires and others   mutually detecting opening/dosing the members of a folding-type cellular phone handset   detection of pushing buttons on a cellular phone handset, etc.       
 
       INDUSTRIAL APPLICABILITY 
       [0082]    The present invention relates to position detecting device and position detecting system applicable to cylinder, automobile, elevator, nursing-care equipment, home security system, cellular phone handset, disconnection detecting system, industrial robot and so on. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0083]      FIG. 1  is a cross-section view and a plane view of the position detecting device  1  in the embodiment of the present invention. 
           [0084]      FIG. 2  is a detailed view of the frame  30  shown in  FIG. 1 . 
           [0085]      FIG. 3  is a diagram showing an example deformation of the resin  60  of the position detecting device  1  shown in  FIG. 1 . 
           [0086]      FIG. 4  is a diagram showing an example deformation of the resin  60  different from  FIG. 3 . 
           [0087]      FIG. 5  is a typical diagram of member  91  of the indicator light body  90  suited to using the resin  60  shown in  FIG. 3 . 
           [0088]      FIG. 6  is a typical diagram of position detecting system  100  including the position detecting device  1  shown in  FIG. 1 . 
           [0089]      FIG. 7  is a principle explanatory diagram of position detecting in position detecting system  100 . 
           [0090]      FIG. 8  is a diagram showing mounting contact-type sensor  200  on the air cylinder  120 . 
           [0091]      FIG. 9  is a diagram showing mounting the non-contact-type sensor  300  on the air cylinder  120 . 
       
    
    
     EXPLANATION OF SIGNS 
       [0000]    
       
           1  position detecting device 
           10  sheath section 
           12 ,  14 ,  16  insulator 
           18 ,  20 ,  22  conductor 
           24 ,  26 ,  28  terminal 
           30  frame 
           40  screw installing section 
           50  Hall IC 
           52  sensor section 
           60  resin 
           100  position detecting system 
           110  piston 
           120  air cylinder 
           130  groove 
           140  magnet 
           150  setscrew 
           160  screwdriver