CN114487508A

CN114487508A - Detection equipment for ejector pin of function test fixture

Info

Publication number: CN114487508A
Application number: CN202210122807.7A
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-02-09
Filing date: 2022-02-09
Publication date: 2022-05-13

Abstract

The invention discloses a detection device for an ejector pin of a function test fixture, which belongs to the technical field of detection fixtures and comprises an upper die, a lower die and a driving mechanism for driving the upper die to move up and down, wherein clamping components for mounting the ejector pin are equidistantly arranged on the upper surface of the lower die, a conducting strip is embedded on the upper surface of the lower die, one end of the conducting strip is positioned on one side of the bottom of the clamping component, the other end of the conducting strip is fixedly connected with an electric connecting rod, a detection lamp is fixed at the top end of the electric connecting rod, an electric connecting terminal is fixed at the top end of the detection lamp, and a connecting component for conducting the electric connecting terminal and an ejector pin circuit is arranged on one side of the bottom of the upper die. And can be convenient for through externally seeing the testing result directly perceivedly through detecting the lamp.

Description

Detection equipment for ejector pin of function test fixture

Technical Field

The invention relates to the technical field of detection jigs, in particular to a detection device for ejector pins of a function test jig.

Background

In the production of mobile phone mainboards or electronic products of the same type, functional test jigs with thimbles are required to be used in large quantities, the diameter of the thimbles of the functional test jigs is 0.7mm at least, and even 0.4mm at least. However, the thimble with such a small diameter causes the thimble to bend and tilt due to external force during production, storage and transportation of the function test fixture, thereby causing misdetection and unusable condition in the subsequent test and use process. The PCBA processing technology comprises the working procedures of PCB manufacturing procedure, component purchasing and inspection, SMT patch assembly, DIP plug-in, PCBA test and the like. The PCBA test is the most critical quality control link in the whole processing procedure and determines the final service performance of the product. The functional test after the PCBA circuit board is assembled is generally called as FCT test, and mainly detects whether the circuit board functions normally. The FCT test fixture comprises a plurality of FCT test thimbles which are distributed according to FCT test sites. During testing, the circuit board is fixed on the jig, and the FCT testing thimble is jacked up by the thimble cylinder and contacts with a welding spot of the circuit board. At the moment, the FCT test thimble collects data and conveys the collected data to the display screen through the data line, and the display screen displays the test structure of the circuit board.

In the detection process of the existing function test jig, the thimble only can be used for detecting the thimble with a fixed diameter, which is very inconvenient; and in the process of detecting the conductivity of the thimble, the upper die or the lower die is under the action of the driving force of the driving mechanism, and when the thimble is contacted to form a closed loop, the thimble is directly pressed on the thimble due to overlarge driving force, so that the thimble is easily bent and deformed to be damaged.

Based on this, the invention designs a detection device for the thimble of the function test fixture, so as to solve the problems.

Disclosure of Invention

The present invention is directed to a device for detecting an ejector pin of a function testing fixture, so as to solve the technical problems mentioned in the background art.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a check out test set of function test tool thimble, includes mould, lower mould and is used for the drive go up the actuating mechanism that the mould reciprocated, the upper surface equidistance of lower mould is installed the centre gripping subassembly that is used for the thimble installation, just the lower mould upper surface inlays and has the conducting strip, the one end of conducting strip is located bottom one side of centre gripping subassembly, just the other end fixedly connected with of conducting strip connects the electric pole, the top of connecting the electric pole is fixed with the detection lamp, the top of detecting the lamp is fixed with the electrical connection terminal, the bottom one side of going up the mould install be used for with the coupling assembling that electrical connection terminal and thimble circuit switched on.

Preferably, the driving mechanism comprises a frame, a hydraulic push rod and a lifting rod fixed to the middle of one side of the upper die, the other end of the lifting rod is connected with a top power output end of the hydraulic push rod, the hydraulic push rod is fixed to one side of the frame, and a lifting groove corresponding to the lifting rod is formed in one side of the top of the frame.

Preferably, a workbench is fixed on one side of the bottom of the lower die, supporting plates are symmetrically fixed on two sides of the workbench, and a base is fixed on one side of the bottom of the supporting plate.

Preferably, rubber anti-slip pads are symmetrically fixed on the periphery of the lower surface of the base, and mounting grooves are symmetrically formed in two sides of the lower surface of the base.

Preferably, the top of the electric terminal is fixed with a protruding joint, one side of the bottom of the protruding joint is provided with a first spring, and the protruding joint is connected with the inner cavity of the top of the electric terminal through the first spring.

Preferably, a supporting pole is fixedly connected between the bottom of the electric terminal and the top of the electric pole, which are positioned outside the detection lamp.

Preferably, the clamping assembly comprises a fixed seat, clamping pieces, a fixed rod, a limiting seat, a moving rod and a second spring, one side of the bottom of the fixed seat is fixed on the upper surface of the lower die, one side of the top of the fixed seat is provided with a clamping groove, one end of the fixed rod is fixed with one side of an inner cavity of the clamping groove, the other end of the fixed rod is fixed with the outer side of one group of clamping pieces, one end of the moving rod is fixed with the outer side of the other group of clamping pieces, the other end of the moving rod penetrates through the other group of inner cavities of the clamping groove in a sliding manner, the limiting seat is fixed in the clamping groove, the moving rod penetrates through two sides of the limiting seat in a moving manner, the second spring is sleeved on the moving rod between the limiting seat and the other side of the inner cavity of the clamping groove, one end of the second spring is connected with the moving rod, and the other end of the second spring is connected with the limiting seat.

Preferably, an adjusting screw is inserted into one side of the top of the limiting seat in a threaded manner, the lower end of the adjusting screw can be in contact with the side surface of the moving rod, and a limiting joint is fixed at the end part of the moving rod, which is positioned outside the fixed seat.

Preferably, coupling assembling include with go up the L type that the mould lower surface contacted and go up gasket and L type lower gasket, the gasket is the component of electrically conductive material under the L type, bottom one side of gasket on the L type with top one side of gasket is connected through the third spring under the L type, the bottom of gasket is fixed with the response piece that is used for responding to discernment thimble position each point coordinate under the L type, the inner chamber of gasket is provided with the power and is used for calculating the data processing module of thimble diameter size under the L type.

Preferably, the data processing module comprises a coordinate data acquisition module for acquiring coordinate data of each point identified by the induction sheet, a coordinate length calculation module for calculating linear distance length data of all coordinate points, and a maximum length output module for inquiring and remotely outputting the maximum coordinate distance length data.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the thimble, the conductive sheet, the external detection lamp, the closed loop formed between the connecting assembly and the thimble are utilized, so that the quick detection work of the conductivity of the thimble can be conveniently realized, and the detection result can be conveniently and visually observed through the detection lamp outside;

2. the thimble clamping assembly is used for mounting the thimbles, so that the thimbles with different diameters can be conveniently subjected to self-adaptive mounting work, and convenience is provided for the mounting work before thimble detection;

3. according to the invention, the connection component is used for respectively carrying out power connection detection on the ejector pin and the power connection terminal, and the damage of the upper die to the ejector pin due to overlarge pressure under the action of the driving force of the driving mechanism is prevented by utilizing the buffering action of the third spring;

4. according to the invention, through induction identification of the diameter information of the thimble, the conductivity of the thimble can be detected, and meanwhile, the accurate detection work of the diameter data of the thimble can be completed.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is another side view of the FIG. 1 embodiment of the present invention;

FIG. 3 is a schematic view of the bottom side structure of FIG. 1 according to the present invention;

FIG. 4 is an enlarged view of the clamping assembly and conductive sheet of the present invention;

FIG. 5 is an enlarged view of the connection assembly of the present invention;

FIG. 6 is a block diagram of a data processing module according to the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1-upper die, 2-lower die, 3-driving mechanism, 4-clamping component, 5-conducting strip, 6-electric connecting rod, 7-detection lamp, 8-electric connecting terminal, 9-connecting component, 10-frame, 11-hydraulic push rod, 12-lifting rod, 13-lifting groove, 14-workbench, 15-supporting plate, 16-base, 17-rubber non-slip pad, 18-mounting groove, 19-convex joint, 20-supporting post rod, 21-fixing seat, 22-clamping piece, 23-fixing rod, 24-limiting seat, 25-moving rod, 26-second spring, 27-clamping groove, 28-adjusting screw, 29-limiting joint and 30-L-shaped upper gasket; a 31-L-shaped lower gasket; 32-a third spring; 33-a sensing piece; 34-a power supply; 35-a data processing module; 36-coordinate data acquisition module; 37-coordinate length calculation module; 38-maximum length output module.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-6, the present invention provides a technical solution: the utility model provides a check out test set of function test tool thimble, includes mould 1, lower mould 2 and is used for the drive go up actuating mechanism 3 that mould 1 reciprocated, the upper surface equidistance of lower mould 2 installs the centre gripping subassembly 4 that is used for the thimble installation, just 2 upper surface inlays of lower mould has conducting strip 5, the one end of conducting strip 5 is located bottom one side of centre gripping subassembly 4, just the other end fixedly connected with of conducting strip 5 connects electrical pole 6, the top of connecting electrical pole 6 is fixed with detection lamp 7, the top of detecting lamp 7 is fixed with electrical connection terminal 8, go up bottom one side of mould 1 and install and be used for with electrical connection terminal 8 and the coupling assembling 9 that the thimble circuit switched on.

It should be noted that, in the process of using the thimble detection device of the functional test fixture to detect the thimble, the thimble is clamped and fixed by the clamping component 4, and the thimble detection work is completed by the loop formed by the thimble, the conducting strip 5, the electric connecting rod 6, the detection lamp 7, the electric connecting terminal 8 and the connecting component 9, and in the specific operation process, the following steps are included:

s1, driving the upper die 1 to move upwards by using the driving mechanism 3, and stopping the upper die 1 from moving upwards after ensuring that the distance between the upper die 1 and the lower die 2 is enough to insert the thimble;

s2, inserting the thimble into the clamping component 4, clamping and fixing, and ensuring that one side of the bottom of the thimble is contacted with the upper surface of the conducting strip 5 inserted into one side of the bottom of the clamping component;

s3, electrifying the driving mechanism 3 again to drive the upper die 1 to move downwards until one side of the lower surface of the connecting assembly 9 is contacted with the top end of the thimble and the other side of the lower surface of the connecting assembly 9 is ensured to be contacted with the electric connection terminal 8;

s4, a thimble, a conducting strip 5, an electric connecting rod 6, a detection lamp 7, an electric connecting terminal 8, a battery on the connecting component 9, and a closed circuit formed between the two sides of the battery and the thimble and the electric connecting terminal 8 respectively, and whether the thimble is damaged or not is judged by observing whether the detection lamp 7 emits light or not.

Through the detection work of the thimble in the mode, whether the thimble is damaged or not can be directly judged by observing whether the detection lamp 7 emits light or not externally, and great convenience is brought to the detection work of the thimble

In a further embodiment, the driving mechanism 3 includes a frame 10, a hydraulic push rod 11 and a lifting rod 12 fixed to the middle portion of one side of the upper die 1, the other end of the lifting rod 12 is connected to a top power output end of the hydraulic push rod 11, the hydraulic push rod 11 is fixed to one side of the frame 10, and a lifting groove 13 corresponding to the lifting rod 12 is formed in one side of the top of the frame 10; as shown in fig. 2, when the driving mechanism 3 is used to drive the upper mold 1 to move up and down, the hydraulic push rod 11 on the frame 10 will act on the power output end of the hydraulic push rod 11 first under the action of the hydraulic motor, so as to drive the upper mold 1 connected with the lifting rod 12 to move up and down, and the lifting rod 12 will move up and down in the lifting groove 13.

In a further embodiment, a workbench 14 is fixed on one side of the bottom of the lower die 2, support plates 15 are symmetrically fixed on two sides of the workbench 14, and a base 16 is fixed on one side of the bottom of the support plates 15; as shown in fig. 1-3, the connection between the supporting plate 15, the base 16 and the worktable 14 facilitates the lower mold 2 to be placed at a designated working height, thereby facilitating the manual insertion and installation of the thimble into the clamping assembly 4.

In a further embodiment, rubber anti-slip pads 17 are symmetrically fixed around the lower surface of the base 16, and mounting grooves 18 are symmetrically formed in both sides of the lower surface of the base 16; as shown in FIG. 3, when the device is used, the rubber anti-skid pad 17 arranged on the base 16 can be used for well playing the anti-skid effect when the device is used on a working surface; when the base 16 is installed and fixed for use, the base 16 and the installation surface are installed and fixed by penetrating installation screws through the installation grooves 18, and the rubber anti-slip pads 17 can achieve buffering and shock absorption between the base 16 and the installation surface, so that the installation surface and the lower surface of the base 16 are protected.

In a further embodiment, a raised joint 19 is fixed at the top end of the electric terminal 8, a first spring is arranged on one side of the bottom of the raised joint 19, and the raised joint 19 is connected with the top inner cavity of the electric terminal 8 through the first spring; as shown in fig. 4, by using the connection between the protruding joint 19 and the first spring and the electrical terminal 8, when the connecting assembly 9 moves downward following the upper die 1 and reaches the top end of the protruding joint 19, the first spring will contract due to the manual pressing force, and can move downward in a self-adaptive manner for a certain distance through the protruding joint 19, so as to prevent the small error of the length dimension due to the processing error of the thimble, and further prevent the connecting assembly 9 from being in insufficient contact with the electrical terminal 8.

In a further embodiment, a support post 20 is fixedly connected between the bottom of the electric terminal 8 positioned outside the detection lamp 7 and the top of the electric rod 6; as shown in fig. 4, in the process of detecting the closed loop of the thimble by using the detection lamp 7, when the upper die 1 drives the connection assembly 9 to move downwards and contact with the electric connection terminal 8, in order to better protect the detection lamp 7, the detection lamp 7 can be effectively prevented from being damaged due to the pressure effect received by the detection lamp 7 by connecting the electric connection terminal 8 and the electric connection terminal 6 by using the support pole 20.

In a further embodiment, the clamping assembly 4 includes a fixing seat 21, a clamping piece 22, a fixing rod 23, a limiting seat 24, a moving rod 25 and a second spring 26, one side of the bottom of the fixing seat 21 is fixed on the upper surface of the lower die 2, one side of the top of the fixing seat 21 is provided with a clamping groove 27, one end of the fixing rod 23 is fixed to one side of the inner cavity of the clamping groove 27, the other end of the fixing rod 23 is fixed to the outer side of one group of the clamping piece 22, one end of the moving rod 25 is fixed to the outer side of the other group of the clamping piece 22, the other end of the moving rod 25 slidably penetrates through the other group of the inner cavity of the clamping groove 27, the limiting seat 24 is fixed in the clamping groove 27, the moving rod 25 movably penetrates through two sides of the limiting seat 24, the second spring 26 is sleeved on the moving rod 25 between the limiting seat 24 and the other side of the inner cavity of the clamping groove 27, one end of the second spring 26 is connected with the moving rod 25, and the other end of the second spring 26 is connected with the limiting seat 24; as shown in fig. 4, when the thimble is clamped by the clamping assembly 4, the thimble can be manually inserted between the two sets of clamping pieces 22, one set of clamping pieces 22 can be kept unchanged by the connection between the fixing rod 23 and the inner wall of the clamping groove 27 on the fixing base 21, the other set of clamping pieces 22 can be moved to one side according to the diameter of the thimble to be adaptively adjusted, and the connection between the moving rod 25 and the limiting base 24 by the second spring 26 can be convenient for ensuring that the inner side surface of the clamping piece 22 connected with the moving rod 25 is tightly attached to the side surface of the thimble; in addition, it is necessary to supplement that the diameter size of the thimble can be known by making scale marks on the moving rod 25 and looking up the distance information of the moving rod 25 extending out of the fixed seat 21 during the installation of the thimble, but the thimble obtained by the method is not accurate enough in size.

In a further embodiment, an adjusting screw 28 is inserted into one side of the top of the limiting seat 24, the lower end of the adjusting screw 28 can contact with the side surface of the moving rod 25, and a limiting joint 29 is fixed at the end of the moving rod 25 located outside the fixed seat 21; as shown in fig. 4, after the thimble is inserted between the two sets of holding pieces 22, the second spring 26 exerts its elastic force to tightly attach the holding pieces 22 to the side surface of the thimble, and the adjusting screw 28 is screwed to tightly attach the lower end of the adjusting screw 28 to the movable rod 25, so that the friction of the movable rod 25 on the stopper seat 24 is increased and locked, thereby preventing the thimble from being laterally tilted or separated from the holding pieces 22 during the detection of the thimble.

In a further embodiment, the connection assembly 9 includes an L-shaped upper pad 30 and an L-shaped lower pad 31 contacting with the lower surface of the upper die 1, the L-shaped lower pad 31 is a conductive member, one side of the bottom of the L-shaped upper pad 30 is connected to one side of the top of the L-shaped lower pad 31 through a third spring 32, a sensing piece 33 for sensing and identifying coordinates of each point of the thimble position is fixed to the bottom of the L-shaped lower pad 31, and a power supply 34 and a data processing module 35 for calculating the diameter and size of the thimble are disposed in an inner cavity of the L-shaped lower pad 31; as shown in fig. 5, when the connection assembly 9 is used to establish circuit closing for the thimble and the electrical connection terminal 8, the detection lamp 7 can conveniently emit light when the thimble is not damaged by the power output of the power supply 34, and the L-shaped lower pad 31 can conveniently move downwards on the lower pad surface 31 and contact with the thimble by the connection between the third spring 32 and the L-shaped upper pad 30, and the coordinate data information of each point on the top end of the thimble can be well sensed by the sensing piece 33 on the L-shaped lower pad 31, and the diameter data of the thimble can be measured by the data processing module 35, so that the further detection work for the diameter information of the thimble can be realized.

In a further embodiment, the data processing module 35 includes a coordinate data collecting module 36 for collecting coordinate data of each point identified by the sensor strip 33, a coordinate length calculating module 37 for calculating linear distance length data of all coordinate points, and a maximum length outputting module 38 for querying and remotely outputting maximum coordinate distance length data; as shown in fig. 6, when the data processing module 35 is used to process the collected coordinate data of the top of the thimble, the coordinate data collecting module 36 is used to collect the coordinate data information of each point identified by induction, the coordinate length calculating module 37 is used to calculate the distance information between each coordinate point of the top of the thimble, the maximum length output module 38 is used to query the maximum coordinate distance first, and the maximum coordinate distance is used as the diameter size of the thimble and is output to the manual end, so that the size information of the thimble can be detected during the process of detecting the conductivity of the thimble.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. The utility model provides a check out test set of function test tool thimble which characterized in that: including last mould (1), lower mould (2) and be used for the drive go up actuating mechanism (3) that mould (1) reciprocated, the upper surface equidistance of lower mould (2) installs centre gripping subassembly (4) that are used for the thimble installation, just lower mould (2) upper surface inlays and has conducting strip (5), the one end of conducting strip (5) is located bottom one side of centre gripping subassembly (4), just the other end fixedly connected with of conducting strip (5) connects electric pole (6), the top of connecting electric pole (6) is fixed with detects lamp (7), the top of detecting lamp (7) is fixed with electrical connection terminal (8), it is used for with to install bottom one side of going up mould (1) electrical connection terminal (8) and coupling assembling (9) that the thimble circuit switched on.

2. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: actuating mechanism (3) include frame (10), hydraulic push rod (11) and with go up mould (1) one side middle part fixed lifter (12) mutually, the other end of lifter (12) with the top power take off end of hydraulic push rod (11) is connected, hydraulic push rod (11) are fixed one side of frame (10), the top one side of frame (10) seted up with corresponding lift groove (13) of lifter (12).

3. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: a workbench (14) is fixed on one side of the bottom of the lower die (2), supporting plates (15) are symmetrically fixed on two sides of the workbench (14), and a base (16) is fixed on one side of the bottom of each supporting plate (15).

4. The apparatus of claim 3, wherein the apparatus comprises: rubber anti-slip pads (17) are symmetrically fixed on the periphery of the lower surface of the base (16), and mounting grooves (18) are symmetrically formed in two sides of the lower surface of the base (16).

5. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: the top of the power connection terminal (8) is fixed with a protruding joint (19), one side of the bottom of the protruding joint (19) is provided with a first spring, and the protruding joint (19) is connected with the inner cavity of the top of the power connection terminal (8) through the first spring.

6. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: and a support post rod (20) is fixedly connected between the bottom of the electric connection terminal (8) and the top of the electric connection rod (6) and positioned outside the detection lamp (7).

7. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: the clamping assembly (4) comprises a fixed seat (21), clamping pieces (22), a fixed rod (23), a limiting seat (24), a moving rod (25) and a second spring (26), one side of the bottom of the fixed seat (21) is fixed on the upper surface of the lower die (2), one side of the top of the fixed seat (21) is provided with a clamping groove (27), one end of the fixed rod (23) is fixed with one side of an inner cavity of the clamping groove (27), the other end of the fixed rod (23) is fixed with the outer side of one group of clamping pieces (22), one end of the moving rod (25) is fixed with the outer side of the other group of clamping pieces (22), the other end of the moving rod (25) penetrates through the other group of inner cavities of the clamping grooves (27) in a sliding manner, the limiting seat (24) is fixed in the clamping groove (27), and the moving rod (25) movably penetrates through two sides of the limiting seat (24), the second spring (26) is sleeved on the moving rod (25) between the limiting seat (24) and the other side of the inner cavity of the clamping groove (27), one end of the second spring (26) is connected with the moving rod (25), and the other end of the second spring (26) is connected with the limiting seat (24).

8. The apparatus of claim 7, wherein the apparatus comprises: an adjusting screw (28) is inserted into one side of the top of the limiting seat (24) in a threaded manner, the lower end of the adjusting screw (28) can be in contact with the side surface of the moving rod (25), and a limiting joint (29) is fixed at the end part of the moving rod (25) located on the outer side of the fixed seat (21).

9. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: coupling assembling (9) include with go up gasket (30) and L type lower gasket (31) on the L type that mould (1) lower surface contacted, gasket (31) are the component of electrically conductive material under the L type, bottom one side of gasket (30) on the L type with top one side of gasket (31) is connected through third spring (32) under the L type, the bottom of gasket (31) is fixed with response piece (33) that are used for response discernment thimble position each point coordinate under the L type, the inner chamber of gasket (31) is provided with power (34) and is used for calculating data processing module (35) of thimble diameter size under the L type.

10. The apparatus for detecting the ejector pin of a function testing jig according to claim 1, wherein: the data processing module (35) comprises a coordinate data acquisition module (36) for acquiring coordinate data of each point identified by the induction sheet (33), a coordinate length calculation module (37) for calculating linear distance length data of all coordinate points, and a maximum length output module (38) for inquiring and remotely outputting the maximum coordinate distance length data.