JP5262837B2 - Electronic device button quality determination method, electronic device manufacturing method, and electronic device button test apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform highly accurate quality determination in measurement at high pushing-down speed during a line application time, concerning a quality determination method of a button of an electronic apparatus, a method for manufacturing the electronic apparatus, and an electronic apparatus button testing device. <P>SOLUTION: This quality determination method includes a process wherein a maximal value determined at a first pushing-down speed is used as a first load of a first characteristic point, a first correction process wherein the first load of the first characteristic point is corrected into a second load of the first characteristic point when pushing down at a second pushing-down speed, a process wherein a minimal value determined at the first pushing-down speed is used as a third load of a second characteristic point, a second correction process wherein the third load of the second characteristic point is corrected into a fourth load of the second characteristic point when pushing down at the second pushing-down speed, and a process wherein quality determination of the button is performed based on the second load and the fourth load. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electronic device button quality determination method, an electronic device manufacturing method, and an electronic device button test apparatus.

  Keys such as mobile phones have a “click feeling” to enhance the operational feeling. FIG. 7 is a diagram for explaining the configuration of a general cellular phone key. FIG. 7 (a) is a schematic plan view before pressing, and FIG. 7 (b) is an AA ′ line in FIG. 7 (a). FIG. 7C is a schematic cross-sectional view taken along the alternate long and short dash line, and FIG. 7C is a schematic cross-sectional view during buckling.

  As shown in FIGS. 7A and 7B, the key is made of a conductive member so as to cover the electrode pair formed of the center electrode 42 and the peripheral electrode 43 formed on the circuit board 41, and a contact portion at the center. The dome 44 having 45 is covered with a sheet 46 to protect it. A key top 47 provided with a pressing portion 49 on the back surface via a rubber 48 is installed so that the pressing portion 49 contacts the top of the dome 44 via the sheet 46. The electrode pair is connected to a power source 51 through a resistor 50, and the key press is detected by the voltage.

  As shown in FIG. 7 (c), when the key pressing force is increased, the thin dome 44 is not gradually deformed, but undergoes buckling called jumping at a certain load and rapidly collapses. It is thought that the reaction force change or impact at this time is a click feeling.

  As a method of quantitatively performing this “click feeling” quality inspection, a method using acceleration or impact sound as a determination index (for example, refer to Patent Document 1 or Patent Document 2), a method for determining from the relationship between stroke and load (for example, Patent Document 3 to Patent Document 6) have been proposed.

Of these, at present, it is generally obtained from the relationship between stroke and load (or time and load in the case of constant speed). For example, as shown in FIG. 8, the reaction force from the keys when pressing generally a click feeling key, once lowered to minimum load P ₂ after reaching a maximum load P _1, rises again. A pass / fail judgment is made by comparing the click rates (P ₁ -P ₂ ) / P ₁ defined by these characteristic loads P ₁ and P ₂ (see, for example, Patent Document 8).

Japanese Patent Laid-Open No. 10-048097 JP 11-191330 A JP 62-217516 A Japanese Patent Laid-Open No. 05-333985 JP 05-273083 A Japanese Patent Application Laid-Open No. 07-055554 JP 2003-173723 A JP 2008-218156 A

  However, the following points are not considered in the conventional proposal. First, there is a problem that the influence of attenuation is not considered. As shown in FIG. 7, the key includes a rubber, and when a product is an object to be inspected, a scratch preventing member is required for a part that presses the key. In general, such a material has a large damping force, and the damping force is often a function of speed.

Therefore, as shown in FIG. 9, pressing at a rate of relatively slow mm / sec order, P ₁ load, P ₂ load will be influenced by the speed. Furthermore, when converted into a click rate, it greatly changes as shown in FIG. 10, and the click rate obtained at a certain speed cannot be directly compared with the click rate obtained at another speed.

  Therefore, when precise measurement is required, such as when determining a reference value, the key is often pressed at an extremely low speed. However, in the inspection of the production line, it is necessary to press the key at high speed in order to shorten the tact time. As described above, there is a high possibility that the speed is changed when the determination criterion is set and when the line is applied. However, it is inefficient to re-measure the determination criterion every time the speed on the line changes.

There is a problem that discontinuity of the minimum load P ₂ to the second is not considered. As described above, the minimum load P ₂ is a discontinuous point of the dome from the state in which a negative spring characteristics buckle, sudden changes in contact with the electrode to the spring characteristics of the substrate. Since the point of essentially curvature infinite, slowed by the influence of frequency band and a low-pass filter of load measuring means, there is a problem that the correct value of P ₂ can not be obtained.

  In particular, as shown in FIG. 11, the faster the pressing speed is, the slower the speed is affected by the frequency band of the load measuring means and the low pass filter. There is a problem that the tact time cannot be shortened.

  Accordingly, an object of the present invention is to enable high-accuracy and high-precision stability by measurement at a high pressing speed when a line is applied.

From one aspect of the present invention, the step of obtaining the first load of the first feature point in the displacement load curve of the button of the electronic device at the first pressing speed, and the second load of the first feature point Correcting to the second load of the first feature point in the displacement load curve when pressed at the pressing speed ; determining the third load of the second feature point of the button in the displacement load curve at the first pressing speed; Based on the second load and the fourth load, correcting the third load of the second feature point to the fourth load of the second feature point in the displacement load curve when pressed at the second pressing speed, There is provided a method for determining pass / fail of a button of an electronic device, comprising the step of determining pass / fail of the button.

From another viewpoint of the present invention, a step of obtaining a first load of a first feature point in a displacement load curve of a button of an electronic device at a first pressing speed, and a step of calculating the first load of the first feature point Correcting the second load of the first feature point in the displacement load curve when pressed at the second pressing speed, and the third load of the second feature point in the displacement load curve at the first pressing speed. A step of determining, a step of correcting the third load of the second feature point to a fourth load of the second feature point in a displacement load curve when pressed at the second pressing speed, and the second load And a step of determining pass / fail of the button based on the fourth load.

Furthermore, from another aspect of the present invention, a database including a plurality of loads of a first feature point and a second feature point in a displacement load curve at a plurality of button pressing speeds of an electronic device, and displacement at a first pressing speed. A measuring unit for obtaining a first load of the first feature point and a third load of the second feature point in a load curve; and the first load and the second feature of the first feature point at the first pressing speed. A correction unit that corrects the third load of a point to the second load of the first feature point and the fourth load of the second feature point in a displacement load curve when the point is pressed at the second pressing speed; An electronic device button inspection apparatus is provided that includes a determination unit that determines pass / fail of the button based on the second load and the fourth load.

  According to the disclosed electronic device button quality determination method, electronic device manufacturing method, and electronic device button test apparatus, it is possible to perform quality control of the click feeling with a constant evaluation index that is not dependent on the pressing speed. Further, since there is no dependency on the pressing speed, a test at a high pressing speed can be performed, and the inspection speed can be increased.

1 is a schematic system configuration diagram of an electronic device button inspection apparatus according to an embodiment of the present invention. It is a load-pressing speed characteristic figure. It is explanatory drawing of an example of the attenuation function C (v). It is a flowchart which shows the quality determination method of the electronic device button of Example 1 of this invention. It is a conceptual explanatory drawing of an approximate polynomial. It is a flowchart which shows the quality determination method of the electronic device button of Example 1 of this invention. FIG. 3 is a configuration explanatory diagram of a key of a general mobile phone. It is explanatory drawing of the load change of a key. It is explanatory drawing of the pressing speed dependence of the maximum load and the minimum load. It is explanatory drawing of the pressing speed dependence of a click rate. It is explanatory drawing of the pressing speed dependence of blunting of minimum load.

  Here, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic system configuration diagram of an electronic device button inspection apparatus according to an embodiment of the present invention, which includes a measurement system and a control system. As shown in FIG. 1A, the measurement system is fixed to an x stage 11 installed on a pedestal 10, a z stage 12 fixed to the x stage 11, and the z stage 12, and is attached to the load cell 14 and the tip of the load cell 14. A pressing portion 13 provided with a finger 15 with a scratch-preventing member attached; a y-stage 16 installed on the pedestal 10; a scratch-preventing base 17 on which an electronic device 18 to be inspected placed on the y-stage 16 is placed; A rotation stage 19 that rotates the inspection electronic device 18 together with the scratch prevention table 17 is provided. When the rotary stage 19 inspects the click characteristic of the horizontal button provided on the side surface of the electronic device 18 to be inspected, the side 15 of the electronic device 18 to be inspected is brought into contact with the finger 15 with the scratch prevention member substantially vertically. Used for.

  On the other hand, as shown in FIG. 1B, the control system is composed of a control device 20, typically a computer. The control device 20 moves a control board 21 for controlling the movement of each stage and a load cell 14 up and down. A calculation unit 23 for obtaining an approximate polynomial of a load-stroke characteristic and an attenuation characteristic from a measurement result by the load cell 14, and a result obtained by the calculation unit 23 using a database stored in the data storage unit 24. A correction unit 25 for correction, and a pass / fail determination unit 26 that compares the correction result corrected by the correction unit 25 with the pass / fail determination criteria stored in the data storage unit 24 are provided.

Such an electronic device button inspection apparatus is used to inspect the electronic device 18 to be inspected, typically a key button of a mobile phone. First, with respect to the electronic device 18 to be inspected of the standard quality, the pressing speed-maximum load and the pressing speed-minimum load are measured for each key button, and the function of speed and load increment, that is, the attenuation function C ₁ is measured. Find (v) and C ₂ (v).

FIG. 2 is a load-pressing speed characteristic diagram. The number of measurement points is m, and characteristic loads P ₁ and P ₂ are measured for _m pressing speeds v _{1 to} v _m , respectively. Here, load of the minimum load P ₂ - is shown pressing speed characteristic diagram, the same measurement also maximum load P _1.

Next, it is assumed that the measurement result P can be approximated by an n-th order (m ≧ n) polynomial, and the obtained m pieces of data are expressed by the following determinant P = Va. Note that when m ≠ n, there is no inverse matrix of the velocity matrix V, so a generalized inverse matrix V ⁺ is obtained.

Here, if both sides of P = Va are multiplied by the generalized inverse matrix V ⁺ , V ⁺ V = 1, so
a = V ⁺ P
Next, is obtained engages number a ₀ ~a _n polynomial from the V + P.
Thus obtained coefficients a ₀ with ~a _n indicating the increase or decrease of the load P for pressing velocity v decay function C a (v) defined by the following equation.
C (v) = a ₀ v ⁿ + a ₁ v ⁿ⁻¹ +... + A _n−1 v = Σa _i v ⁿ⁻ⁱ
Note that C ₁ (v) is an attenuation function related to the maximum value P ₁ , and C ₂ (v) is an attenuation function related to the minimum value P ₂ .

FIG. 3 is an explanatory diagram of an example of the damping function C (v). This damping function C (v) is equivalent to that obtained by removing the offset of the ideal curve of the load pressing speed characteristic diagram shown in FIG. Become. Therefore, the difference between the loads P _i (v _a ) and P _i (v _s ) at any two pressing speeds v _a and v _s in the load pressing speed characteristic diagram shown in FIG. 2 is the attenuation shown in FIG. It becomes equal to the difference between the attenuation values C _i (v _a ) and C _i (v _s ) at any two pressing speeds v _a and v _s in the function C (v).

Therefore, for example, the reference value for the pass / fail determination is determined by adding a necessary margin to the statistical data of the click rate of the product that has become non-defective. For example, since the accuracy of the reference value, for example, the click rate increases as the key button pressing speed is slower, the maximum value P ₁ (v _s ) and the minimum value P ₂ (v _s ) are measured at a low speed v _s , click-through rate _{[P 1 (v s) -P 2} (v s) ] _/ P 1 seek _{(v s).} A margin required for the statistical data of the click rate, for example, 3σ or 4σ, is taken into account as a reference value for pass / fail judgment. Here, it is assumed that all products have the same attenuation characteristic with respect to a standard quality product.

Next, the measurement of the maximum value P ₁ and the minimum value P ₂ with respect to the test electronics, performed at relatively high pressing speed v _a to shorten the tact time. Be determined in this state CTR _{[P 1 (v a) -P 2} (v a) ] _/ P 1 _{(v a),} since different from the depression velocity _{v s} when the pressing speed is calculated a reference value for determining quality As can be seen from FIG. 9, it cannot be directly compared.

Therefore, to convert the load in pressing speed v _s using the attenuation function C (v) shows the measurement results in the pressing speed v _a in FIG. As described above, the attenuation characteristic is the same, by using a decay function C (v), to convert the load P in the pressing speed _{v a} a _{(v a)} in load P _{(v s)} in pressing speed _{v s} be able to.

In other words, the maximum value _{P 1} is,
P ₁ (v _a ) = P ₁ (v _s ) + C ₁ (v _a ) −C ₁ (v _s )
Next, when determining the load _P 1 _{(v s)} in pressing speed _{v s} from the equation _{P 1 (v s) = P} 1 (v a) -C 1 (v a) + C 1 (v s)
It becomes. On the other hand, the minimum value _{P 2} is
_{P 2 (v a) = P} 2 (v s) + C 2 (v a) -C 2 (v s)
Next, when determining the load _P 2 _{(v s)} in pressing speed _{v s} from the equation _{P 2 (v s) = P} 2 (v a) -C 2 (v a) + C 2 (v s)
It becomes.

Using the load thus converted, the click rate is obtained as the click rate [P ₁ (v _s ) −P ₂ (v _s )] / P ₁ (v _s ) at the pressing speed v _s . The pass / fail judgment is performed by comparing with the obtained pass / fail reference value. In this case, as the pass / fail judgment criteria, data determined for one standard key may be used, or data determined for all keys of a certain standard terminal may be called for each measured key.

Thus, in the embodiment of the present invention, by using an attenuation function C (v) was determined for previously non-defective, a predetermined pressing velocity v load was measured in _a P (v _a), accurate measurement The pass / fail judgment is performed by converting the load P (v _s ) at a possible low pressing speed v _s . Therefore, it becomes possible to perform quality determination similar high accuracy as in the case of low-depression velocity v _s in a short tact time.

In the above description, the use of a click rate determination indicator, for each key, pressing rate for maximum load P ₁ and minimum load P ₂ - seeking load characteristic curve, which depression rate - from the load characteristic curve The attenuation function C (v) is obtained. For this reason, the number of measurements increases, and it takes a lot of time to construct a database in advance.

  Therefore, the gradient is calculated for the maximum load and the minimum load at the two pressing speeds as the determination index, and the necessary margin (± α) is added to the statistical data of the gradient obtained for the non-defective product to determine the reference value for pass / fail judgment. To do. Thereby, the database construction time can be greatly shortened.

In this case, the maximum load P ₁ (v ₁ ), P ₁ (v ₂ ) and the minimum load P ₂ (v ₁ ), P at the same two pressing speeds v ₁ , v ₂ as the database for the key buttons of the electronic device to be inspected. ₂ (v ₂ ) and then the gradient c _{1 for the} local maximum and the gradient c ₂ for the local minimum, respectively
c ₁ = [P ₁ (v ₂ ) −P ₁ (v ₁ )] / (v ₂ −v ₁ )
c ₂ = _{[P 2 (v 2) -P 2} (v 1) ] _/ (v 2 _-v 1)
Asking. When the c ₁ and c ₂ satisfy the pass / fail judgment criteria, the product is judged as a non-defective product.

In the above determination method, since the influence of the dynamic response of the key button is not reflected, there is a possibility that a slip-through or an excessive defect determination may occur when a line is applied. That CTR obtained from P ₁ load and P ₂ load, if pressed at a low speed, although the advantages that can be operated as an absolute index comparable in any instrument there is only quasi-static indices. However, as described above, click feeling is dynamic response when the dome buckling reaction force decreases abruptly from P _1. Therefore, the click rate is not an index that completely matches the actual good touch.

In this case, the depression speed of up to a maximum load - the slope of the load characteristic curve as an indicator of stiffness K _1, pressing speed after minimum load - the inclination of the load characteristic curve indicative of the stiffness K _2. By using these stiffnesses K ₁ and K ₂ together with the attenuation C (v) as a determination criterion, it is possible to determine whether the quality is close to the actual feeling. For example, qualitatively, it is determined that a key having a large stiffness K has a good feel and a key having a large attenuation C (v) has a poor feel.

  Based on the above, next, a quality determination method for electronic device buttons according to the first embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart illustrating the electronic device button pass / fail determination method according to the first embodiment of the present invention.

As shown in FIG.
Step S _1: set to prevent scratches stand a mobile phone as an object to be inspected electronic devices. Then
Step S _2: by driving the x stage and y stage moves the scratch-resistant member with a finger to a predetermined key position. Then
Step _{S 3:} lowering the z stage speed v. Then
Step _{S 4:} starting the stroke measurement. Then
Step _{S 5:} to start a load measurement.
Step S ₆ : It is determined whether or not the load has reached a predetermined stop load to prevent destruction, and load measurement is continued until the load reaches the stop load. Then
Step S _7: Upon reaching the stop load, stops the load measuring stops z stage. Then
Step _S 8: raising the z stage.
The steps so far are performed in the measurement system, and the subsequent steps are performed in the control system.

Next, in the calculation unit of the control device,
Step S ₉ : Second-order differentiation of the measured load data string. Then
Step S ₁₀ : Search for the stroke amount x ′ ₂ corresponding to the minimum load P ₂ in the vicinity of the maximum value of the second-order differentiated value. Then
Step S ₁₁ : Search for the stroke amount x ′ ₁ corresponding to the maximum load P ₁ in the region of the stroke amount x ′ ₂ or less. Then
Step S ₁₂ : An approximate polynomial f _P1 (x) of the load P is obtained in the range of x ′ ₁ ± (x ′ ₂ −x ′ ₁ ). Then
Step S ₁₃ : In the range of x ′ ₁ ± (x ′ ₂ −x ′ ₁ ), the maximum value of the approximate polynomial f _P1 (x) is defined as P ₁ (v). Then
Step S ₁₄ : An approximate polynomial f _P2 (x) of the load P is obtained in the range of stroke amounts x ′ _{1 to} x ′ ₂ . Then
Step S ₁₅ : An approximate polynomial g _P2 (x) is obtained in an arbitrary range after the stroke amount x ′ ₂ . Then
Step S ₁₆ : The intersection point of the approximate polynomial f _P2 (x) and the approximate polynomial g _P2 (x) is obtained as the minimum load P ₂ (v).

FIG. 5 is a conceptual explanatory diagram of the approximate polynomial, FIG. 5 (a) is a load-stroke amount curve in the measurement data, and FIGS. 5 (b) and 5 (b) are explanatory diagrams of each approximate polynomial. As shown in FIG. 5C, the minimum load P ₂ (v) is accurately obtained by setting the intersection of the approximate polynomial f _P2 (x) and the approximate polynomial g _P2 (x) to the minimum load P ₂ (v). Can be evaluated.

As shown in FIG. 10, the faster the pressing speed, the more noticeably the minimum value in the measurement data becomes dull due to the influence of the frequency band of the load measuring means and the low-pass filter. However, by using the approximate polynomial f _P2 (x) and the approximate polynomial g _P2 (x), the minimum load P ₂ can be obtained with high accuracy even if the pressing speed is increased.

  Therefore, since the measurement can be performed at a higher pressing speed, the tact time can be shortened. In addition, since the influence of the frequency band of the load measuring means and the low-pass filter can be greatly reduced, the frequency band of the measurement system can be lowered, and thereby the cost of the inspection apparatus can be reduced.

Referring again to FIG. 4, next, in the correction unit of the control device,
Step S ₁₇ : Attenuation correction is performed using the attenuation functions C ₁ (v) and C ₂ (v) stored in advance in the data storage unit for the maximum load P ₁ (v) and the minimum load P ₂ (v). By this attenuation correction, it is converted into loads P ₁ (v _s ) and P ₂ (v _s ) at the pressing speed v _s when the determination reference value is obtained. Then
Step S ₁₈ : Click rate α = [P ₁ (v _s ) −P ₂ (v _s )] / P ₁ (v _s ) is obtained.

Finally, in the pass / fail judgment unit of the control device,
Step S ₁₉ : The obtained click rate α is compared with a click rate α _{s serving} as a criterion stored in advance in the data storage unit. Here, α> α _s is determined as a non-defective product, and α ≦ α _s is determined as a defective product. Even when the measurement of the required maximum load P ₁ and minimum load P ₂ in constructing the database, obtaining step on the same steps as steps S _{1 ~} step S ₁₆ described above.

As described above, in Example 1 of the present invention, when the damping function C (v) obtained in advance based on a non-defective product is used, the load due to the pressing speed v at the time of measurement on the line is set as the pass / fail judgment reference value. It is converted to the load in a slow pressing speed v _s of. Therefore, even if the pressing speed v at the time of measurement on the line is increased, it is possible to determine the quality with high accuracy, so that the tact time can be greatly shortened.

Next, with reference to FIG. 6, the quality determination method of the electronic device button of Example 2 of this invention is demonstrated. FIG. 6 is a flowchart showing a method for determining pass / fail of an electronic device button according to the second embodiment of the present invention.
Step s ₁ : A mobile phone as an electronic device to be inspected is set on a scratch prevention stand. Then
Step s ₂ : The x stage and the y stage are driven to move the finger with the scratch preventing member to a predetermined key position. Then
Step s ₃ : The pressing speed is set to v ₁ . Then
Step s ₄ : The maximum load P ₁ (v ₁ ) and the minimum load P ₂ (v ₁ ) are measured. During this measurement, it performs stepping on exactly the same steps as steps S _{3 ~} step S ₁₆ shown in Example 1 above.

Then
Step _{s 5:} setting a pressing speed _{v 2.} Then
Step s ₆ : The maximum load P ₁ (v ₂ ) and the minimum load P ₂ (v ₂ ) are measured. Also when the measurement is performed by stepping on exactly the same steps as steps S _{3 ~} step S ₁₆ shown in Example 1 above.

Next, in the calculation unit of the control device,
Step s ₇ : The gradient c ₁ related to the attenuation of the maximum load P ₁ is obtained as c ₁ = [P ₁ (v ₂ ) −P ₁ (v ₁ )] / (v ₂ −v ₁ ). Then
Step s ₁₈ : The gradient c ₂ relating to the attenuation of the minimal load P ₂ is obtained as c ₁ = [P ₂ (v ₂ ) −P ₁ (v ₁ )] / (v ₂ −v ₁ ).

Finally, in the pass / fail judgment unit of the control device,
Step s ₉ : It is determined whether or not the obtained gradients c ₁ and c ₂ are within an allowable range considering the margin β of the gradients c _s1 and c _{s2 that} are stored in advance in the data storage unit. Here, c _s1 −β ₁ <c ₁ <c _s1 + β ₁ and c _s2 −β ₂ <c ₂ <c _s2 + β ₂ are determined to be non-defective products, and the others are determined to be defective products. .

In the second embodiment, it is only necessary to measure at the two measurement points v ₁ and v ₂ when constructing the pass / fail judgment database. Therefore, the time required for constructing the database can be reduced. .

10 pedestal 11 x stage 12 z stage 13 pressing part 14 load cell 15 finger 16 with flaw prevention member y stage 17 flaw prevention pedestal 18 inspected electronic device 19 rotary stage 20 control device 21 control board 22 AD converter 23 arithmetic unit 24 data storage Unit 25 correction unit 26 pass / fail judgment unit 41 circuit board 42 center electrode 43 peripheral electrode 44 dome 45 abutting unit 46 sheet 47 key top 48 rubber 49 pressing unit 50 resistance 51 power source

Claims (5)

Obtaining a first load of the first feature point in the displacement load curve of the button of the electronic device at a first pressing speed;
Correcting the first load of the first feature point to a second load of the first feature point in a displacement load curve when pressed at a second pressing speed;
Obtaining a third load of a second feature point of the button in a displacement load curve at the first pressing speed;
Correcting the third load of the second feature point to a fourth load of the second feature point in a displacement load curve when pressed at the second pressing speed;
And a step of determining pass / fail of the button on the basis of the second load and the fourth load.   The button of the electronic device according to claim 1, wherein the correcting step corrects based on a plurality of loads of the first feature point and the second feature point at a plurality of predetermined pressing speeds. Pass / fail judgment method. Obtaining a first load of the first feature point in the displacement load curve of the button of the electronic device at a first pressing speed;
Correcting the first load of the first feature point to a second load of the first feature point in a displacement load curve when pressed at a second pressing speed;
Obtaining a third load of a second feature point in the displacement load curve at the first pressing speed;
Correcting the third load of the second feature point to a fourth load of the second feature point in a displacement load curve when pressed at the second pressing speed;
And a step of determining pass / fail of the button based on the second load and the fourth load. A database comprising a plurality of loads of first feature points and second feature points in a displacement load curve at a plurality of pressing speeds of buttons of an electronic device;
A measurement unit for obtaining a first load of the first feature point and a third load of the second feature point in a displacement load curve at a first pressing speed;
The first feature point in a displacement load curve when the first load of the first feature point and the third load of the second feature point are pressed at the second press speed at the first press speed. A correction unit that corrects the second load and the fourth load of the second feature point;
An electronic device button inspection apparatus comprising: a determination unit configured to determine pass / fail of the button based on the second load and the fourth load. The step of obtaining the first feature point is a step of measuring a load-stroke characteristic in a plurality of stroke amounts by pressing a button of an electronic device at a constant pressing speed;
The load - by second order differential of the data string of the stroke characteristic, determining a first stroke x ₂ corresponding to the maximum load at the maximum value near the second-order differential value,
In the first stroke x ₂ following stroke region, and determining a second stroke x ₁ corresponding to the maximum load,
The approximate polynomial fP ₁ (x) of the load-stroke characteristic is obtained in the range of x ₁ ± (x ₂ −x ₁ ) centered on the second stroke amount x ₁ , and the approximate polynomial fP ₁ (x) Is the process of finding the maximum value of
Obtaining the second feature point;
In the first stroke volume x ₂ range from the second stroke x _1, the load - along with approximate polynomial fP 2 Request _(x) of the stroke characteristic, the first stroke x ₂ or more strokes region in the load - approximate polynomial _gP 2 obtains the (x) of the stroke characteristic, characterized in that the intersection between the approximate polynomial _fP 2 (x) and approximate polynomial _gP 2 (x) is a step of the minimum point The quality determination method of the button of the electronic device of Claim 1 or Claim 2 .

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