POS machine safety contact pressure test device and test method

[0041] Please refer to Figure 1-2 , The first embodiment of the present invention is:

[0042] The present invention provides a POS machine safety contact pressure test device, which includes a circuit board provided with safety contacts, the circuit board is provided with a cantilever beam, the cantilever beam includes a free end and a circuit The fixed end of the board connection, the safety contact is arranged on the free end, and the fixed end is provided with a strain gauge for obtaining the strain value generated by the deformation of the cantilever beam and the circuit board. The processor is used to calculate the pressure value of the safety contact of the POS machine according to the acquired strain value.

[0043] The cantilever beam is a cantilever beam cut from the original circuit board, the surrounding grooves of the cantilever beam are open, and the safety contacts are arranged on the free end of the cantilever beam, which greatly reduces the influence of other components of the circuit board on the cantilever beam , You can improve the accuracy of the measurement.

[0044] The circuit board is provided with through holes. The through hole is used to weaken the energy transmission of the deformation of other parts of the circuit board, thereby protecting the cantilever beam from being affected and improving the accuracy of measurement.

[0045] The through hole is located at the reverse extension of the cantilever beam, which can improve the isolation effect of the cantilever beam and block the energy transmission of deformation of other parts of the circuit board as much as possible.

[0046] Further, the above-mentioned through hole is a bar-shaped through hole, and the bar-shaped through hole is perpendicular to the extending direction of the cantilever beam. When the bar-shaped through hole is perpendicular to the extending direction of the cantilever beam, the energy transferred from the deformation of other parts of the circuit board will be transmitted along the vertical axis of the bar-shaped through hole, that is, in the direction perpendicular to the extending direction of the cantilever beam. It can block the energy transfer of the deformation of other parts of the circuit board to the greatest extent.

[0047] The cantilever beam is rectangular, and the cross-sectional length of the strip through hole is equal to the width of the cantilever beam. When the cross-sectional length of the bar-shaped through hole is equal to the width of the cantilever beam, the energy transmission of the deformation of other parts of the circuit board can be blocked to the greatest extent, and the circuit board space occupied by the through hole can be reduced.

[0048] A fixed interval is provided between the through hole and the fixed end of the cantilever beam. A fixed interval is provided between the through hole and the fixed end of the cantilever beam, which does not affect the fixing strength of the cantilever beam.

[0049] Such as figure 2 , The processor calculates the pressure value of the safety contact of the POS machine according to the acquired strain value. The specific calculation formula is as follows:

[0050]

[0051] Where F is the pressure value, L is the position where the force value is applied, x is the position where the strain is measured, W is the bending section coefficient, E is the elastic modulus, ε x Is the strain value at x. In the stage of elastic deformation, the stress and strain of the material become proportional (that is, in accordance with Hooke's law), and the proportional coefficient is called the elastic modulus.

[0052] When a certain pressure is applied to the safety contact, the cantilever beam produces a slight deformation. The bending strain of the cantilever beam can be measured by the strain gauge, and the applied pressure value is calculated according to the above-mentioned mechanical formula, and the pre-pressure value of the silicone pad can be obtained.

[0053] Please refer to Figure 1-2 , The second embodiment of the present invention is:

[0054] On the basis of the first embodiment, the corresponding strain gauge is further defined, specifically: the strain gauge is located in the middle position between the safety contact and the end of the fixed end. Setting the strain gauge in the middle position between the safety contact and the fixed end can improve the sensitivity of the strain gauge, and then accurately obtain the strain value generated by the deformation of the joint between the cantilever beam and the circuit board, and calculate the POS based on the strain value The pressure value of the safety contact of the machine, the pressure value at this time is the most accurate. The strain gauge is wiredly connected to the processor. The above-mentioned strain gauges are connected by wires, and the collected strain values ​​are transmitted to the processor (the processor is a peripheral strain tester) through wires, which can improve the transmission efficiency and safety and stability, because the strain is the internal micro deformation of the circuit board , The wire of the strain gauge hardly affects it.

[0055] In summary, the present invention provides a POS machine safety contact pressure test device and test method, which cut the circuit board into a special shape to form a cantilever beam, and set the safety contact on the free end of the cantilever beam It can effectively avoid the influence of the deformation of the other parts of the circuit board on the measured value of the strain gauge when the POS machine is locked. When the joint between the cantilever beam and the circuit board is deformed, the strain gauge set on the fixed end will get the strain value , And calculate the pressure value of the safety contact of the POS machine through the processor. The whole test process has nothing to do with the compression of the silicone pad, so that the pressure value of the safety contact can be accurately measured when the POS machine is locked.