A method for obtaining the single-axis force point of a key by two-point force measurement

Abstract

The invention discloses a method for obtaining a single-axis force point of a key by two-point force measurement, comprising the following steps: four half-bridge sensors form two full-bridge sensors; the two full-bridge sensors are connected to a force point detection module of a high-precision ∑△ADC, wherein the force values ​​of the two full-bridge sensors are Weight1 and Weight2 respectively; the specific force point of the key is judged by the proportional relationship value Scale of Weight1 and Weight2; the invention can use the high-precision ∑△ADC to measure the sum of the two full-bridge sensors to judge whether there is a key action and whether the key is under force, measure the force ratio of the two full-bridge sensors to quickly and accurately determine the position of the force point, the test data error is small, and the key can be tested at multiple points, so that different positions of the key can be pressed to obtain the force values ​​of the key at different force points, thereby realizing all-round force detection of the key and facilitating more accurate judgment of the pressure resistance and durability of the key.

Description

Technical Field

[0001] The invention relates to the technical field of single-axis force point testing of keyboard keys, and in particular to a method for obtaining single-axis force points of keys by two-point force measurement. Background Art

[0002] Keys are common facilities on many electronic devices such as keyboards, laptops, computers, or CNC mechanical controllers. They are keys that are pressed by hand. Among them, keyboards are one of the input devices that are most frequently used in daily life. The feel of the keyboard keys is particularly important. The feel is mainly determined by the degree of resistance of the keys. To judge the feel of the keyboard, the test will be conducted from the following aspects: whether the key elasticity is moderate, whether the key force is uniform, whether the key cap is loose or shaking, and whether the key travel is appropriate. Among them, whether the key force is uniform is the key to directly affecting the service life and quality of the keyboard. Therefore, it is necessary to detect the key force and force points to view and detect the force conditions of pressing the keys at different positions.

[0003] For key detection, the key is often placed on a piezoelectric sensor and a displacement sensor, and then used in conjunction with a MAYYMOS monitor to detect the key. During the test, the tester directly presses the key and uses the piezoelectric sensor to sense the force of the press. During the test, the tester needs to apply different forces to perform key force detection. Such detection is difficult to perform multi-point testing on the key, and it is difficult to accurately view the force points on the key during the test. Since the mechanical force on the key is different at different force points, the data during the test needs to be transmitted to the monitor for display through the piezoelectric sensor and the displacement sensor. The test data has a large error, and it is difficult to perform all-round force detection on the key. The operation steps are relatively cumbersome. Therefore, a method for obtaining the single-axis force point of the key by two-point force measurement is provided. Summary of the invention

[0004] The purpose of the present invention is to provide a method for obtaining the single-axis force point of a key by two-point force measurement, so as to solve the problems raised in the above background technology that the existing testing technology is difficult to conduct multi-point testing, difficult to perform all-round force detection on the key, large test data errors, and cumbersome operation steps.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for obtaining a single-axis force point of a key by two-point force measurement comprises the following steps:

[0007] Four half-bridge sensors Cell1, Cell2, Cell3 and Cell4 are used to form two full-bridge sensors, and force plates are installed on the two full-bridge sensors;

[0008] The two full-bridge sensors are connected to the force point detection module of the high-precision ∑△ADC to obtain a differential voltage value output by each full-bridge sensor, which is the magnitude of the mechanical force received by the two half-bridge sensors. The force values ​​of the two full-bridge sensors are Weight1 and Weight2 respectively.

[0009] The sum value X of Weight1 and Weight2 is used to determine whether there is a key action at present, and the relationship is: X = Weight1 + Weight2;

[0010] The specific force point position on the single axis of the key is determined by the proportional relationship value Scale between Weight1 and Weight2. The proportional relationship value formula is: Scale = Weight1 / X or Scale = Weight2 / X.

[0011] Furthermore, the method further comprises the following steps:

[0012] The common mode voltage of half-bridge sensor Cell2 is used as AI1, the common mode voltage of half-bridge sensor Cell1 is used as AI0, the common mode voltage of half-bridge sensor Cell4 is used as AI3, and the common mode voltage of half-bridge sensor Cell3 is used as AI2;

[0013] Among them, the differential mode voltage ADC calibration value between AI0 and AI1 is K1, and the differential mode voltage zero point value between AI0 and AI1 is Z1;

[0014] The differential mode voltage ADC calibration value between AI2 and AI3 is K2, and the differential mode voltage zero point value between AI2 and AI3 is Z2;

[0015] Arrange half-bridge sensor Cell1 and half-bridge sensor Cell2 from top to bottom on the left side of the force-bearing plate, and use the left side of the force-bearing plate as force calibration point A. Arrange half-bridge sensor Cell4 and half-bridge sensor Cell3 from top to bottom on the right side of the force-bearing plate, and use the right side of the force-bearing plate as force calibration point B.

[0016] When measuring the force calibration point A, the ADC value of the differential mode voltage between AI0 and AI1 is A1, and the ADC value of the differential mode voltage between AI2 and AI3 is A2.

[0017] Its differential mode voltage VA1 = A1-Z1, differential mode voltage VA2 = A2-Z1;

[0018] When measuring the force calibration point B, the differential mode voltage ADC value between AI0 and AI1 is B1, and the differential mode voltage ADC value between AI2 and AI3 is B2.

[0019] Its differential mode voltage VB1 = B1-Z1, differential mode voltage VB2 = B2-Z1;

[0020] Substitute the following formula to obtain the force values ​​of Weight1 and Weight2:

[0021] Weight1=VA1*K1+VA2*K2, Weight2=VB1*K1+VB2*K2.

[0022] Furthermore, the force coefficients K1 and K2 of the two full-bridge sensors are obtained through a second-order determinant, and the second-order determinant is as follows:

[0023]

[0024]

[0025] Furthermore, the half-bridge sensor adopts a force sensor or a weighing sensor, and a metal sheet is provided on the half-bridge sensor, and two strain gauges are attached to the metal sheet.

[0026] Furthermore, the force point detection module includes a main control MCU analog-to-digital conversion unit connected to four half-bridge sensors, and a power digital signal output unit is connected to the SCL pin end and the SDA pin end of the main control MCU analog-to-digital conversion unit.

[0027] Furthermore, a counter is connected to an output end of the main control MCU analog-to-digital conversion unit, and the counter is used to display 23-bit ADC data obtained by amplifying the voltage generated by the stress on the stress-bearing plate by 128 times by the main control MCU analog-to-digital conversion unit.

[0028] Furthermore, the input end of the main control MCU analog-to-digital conversion unit is connected to a simulation debugging interface, which adopts a 6P interface of HY_ICP 2.54, and the output end of the main control MCU analog-to-digital conversion unit is connected to an LED lamp assembly.

[0029] The beneficial effects of the present invention are as follows: the present invention can use a high-precision ∑△ADC to measure the sum of the two full-bridge sensors to determine whether there is a key action and whether the key is under force, and measure the force ratio of the two full-bridge sensors to quickly and accurately determine the position of the force point. The test data has a small error and is easy to operate. It can perform multi-point testing on the key, and it is convenient to press different positions of the key to obtain the force values ​​of the key at different force points, thereby realizing all-round force detection of the key, helping to more accurately determine the pressure resistance and durability of the key, and facilitating the long-term use of the key. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the force-bearing plate of the present invention;

[0032] Figure 3 It is a schematic diagram of the use principle of four half-bridge sensors of the present invention;

[0033] Figure 4 This is a circuit diagram of a force point detection module of a high-precision ∑△ADC of the present invention;

[0034] Figure 5 The circuit diagram of the analog-to-digital conversion unit of the main control MCU of the present invention.

[0035] In the figure: 1 main control MCU analog-to-digital conversion unit, 2 counter, 3 full-bridge sensor, 31 force plate, 4 power digital signal output unit, 5 simulation debugging interface, 6 LED light assembly. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1-5 , which provides a technical solution for the present invention, a method for obtaining a single-axis force point of a key by two-point force measurement, comprising the following steps:

[0038] Four half-bridge sensors Cell1, Cell2, Cell3 and Cell4 are used to form two full-bridge sensors 3, a force-bearing plate 31 is added to the two full-bridge sensors 3, and a button is installed on the force-bearing plate 31;

[0039] The two full-bridge sensors 3 are connected to the force point detection module of the high-precision ∑△ADC to obtain a differential voltage value output by each full-bridge sensor 3, which is the magnitude of the mechanical force received by the two half-bridge sensors. The force values ​​of the two full-bridge sensors 3 are Weight1 and Weight2 respectively.

[0040] The sum value X of Weight1 and Weight2 is used to determine whether there is a key action at present, and the relationship is: X = Weight1 + Weight2;

[0041] The specific force point position on the single axis of the key is determined by the proportional relationship value Scale between Weight1 and Weight2. The proportional relationship value formula is: Scale = Weight1 / X or Scale = Weight2 / X.

[0042] The method for obtaining the single-axis force point of a key by two-point force measurement also includes the following steps:

[0043] The common mode voltage of half-bridge sensor Cell2 is used as AI1, the common mode voltage of half-bridge sensor Cell1 is used as AI0, the common mode voltage of half-bridge sensor Cell4 is used as AI3, and the common mode voltage of half-bridge sensor Cell3 is used as AI2;

[0044] Among them, the differential mode voltage ADC calibration value between AI0 and AI1 is K1, and the differential mode voltage zero point value between AI0 and AI1 is Z1; the differential mode voltage ADC calibration value between AI2 and AI3 is K2, and the differential mode voltage zero point value between AI2 and AI3 is Z2;

[0045] The half-bridge sensor Cell1 and the half-bridge sensor Cell2 are arranged from top to bottom on the left side of the force-bearing plate 31, and the left side of the force-bearing plate 31 is used as the force calibration point A. The half-bridge sensor Cell4 and the half-bridge sensor Cell3 are arranged from top to bottom on the right side of the force-bearing plate 31, and the right side of the force-bearing plate 31 is used as the force calibration point B. During the test, the following is performed:

[0046] When measuring the force calibration point A, the differential mode voltage ADC value between AI0 and AI1 is A1, and the differential mode voltage ADC value between AI2 and AI3 is A2.

[0047] Its differential mode voltage VA1 = A1-Z1, differential mode voltage VA2 = A2-Z1;

[0048] When measuring the force calibration point B, the differential mode voltage ADC value between AI0 and AI1 is B1, and the differential mode voltage ADC value between AI2 and AI3 is B2.

[0049] Its differential mode voltage VB1 = B1-Z1, differential mode voltage VB2 = B2-Z1;

[0050] Substitute the following formula to obtain the force values ​​of Weight1 and Weight2:

[0051] Weight1=VA1*K1+VA2*K2, Weight2=VB1*K1+VB2*K2.

[0052] In this embodiment, the force coefficients K1 and K2 of the two full-bridge sensors 3 are obtained by the second-order determinant, and the second-order determinant is as follows:

[0053]

[0054]

[0055] In this embodiment, the force point detection module includes a main control MCU analog-to-digital conversion unit 1 connected to four half-bridge sensors, and the SCL pin end and the SDA pin end of the main control MCU analog-to-digital conversion unit 1 are connected to a power digital signal output unit 4; a counter 2 is connected to an output end of the main control MCU analog-to-digital conversion unit 1, and the counter 2 is used to display the 23BitADC data obtained by amplifying the voltage generated by the force plate 31 by 128 times by the main control MCU analog-to-digital conversion unit 1; the input end of the main control MCU analog-to-digital conversion unit 1 is connected to a simulation debugging interface 5, and the simulation debugging interface 5 adopts HY_ICP The 6P interface of 2.54, that is, the simulation debugging interface 5 mentioned, has six pin ends of VSS, VDD, SDO, SDI, SCK and VPP. When in use, the simulation debugging interface 5 is directly connected to an external power supply to provide driving power for the force point detection module. The external power supply can be a UPS uninterruptible power supply. The structure and principle of the UPS uninterruptible power supply are well-known technologies in the market, so they are not elaborated here; wherein, the output end of the main control MCU analog-to-digital conversion unit 1 is connected to an LED lamp assembly 6, and the LED lamp assembly 6 includes at least one group of LED lights; the half-bridge sensor adopts a force sensor or a weighing sensor, wherein, a force sensor of the SB300KG type or the PST1T type is adopted, and when a weighing sensor is adopted, a columnar CRC50KG type or a CZL635 type weighing sensor is adopted but not limited to, and a metal sheet is provided on the half-bridge sensor, and two strain gauges are attached to the metal sheet.

[0056] Among them, the metal sheet adopts but is not limited to copper sheet; the strain gauge mentioned adopts but is not limited to resistance strain gauge, wherein the working principle of the resistance strain gauge is based on the strain effect, that is, when the conductor or semiconductor material produces mechanical deformation under the action of external force, its resistance value changes accordingly. This phenomenon is called "strain effect". The structure and principle of the strain gauge are well-known technologies in the market, so they are not elaborated here; when the metal sheet is subjected to a force in a fixed direction, the resistance values ​​of the two strain gauges will increase and decrease with the size of the force, and the two half-bridges will be combined into a full bridge. By providing a fixed voltage to the full-bridge sensor 3, the full-bridge sensor 3 outputs a differential voltage, and this differential voltage represents the size of the mechanical force received by the two half-bridge sensors.

[0057] It should be noted that the main control MCU analog-to-digital conversion unit 1 adopts but is not limited to the HY17P48_20SSOP type ADC converter; the AI0 pin end, AI1 pin end, AI2 pin end and AI3 pin end of the main control MCU analog-to-digital conversion unit 1 are respectively connected to the half-bridge sensor Cell1, half-bridge sensor Cell2, half-bridge sensor Cell3 and half-bridge sensor Cell4, and the counter 2 is connected to the PWM pin end and the LVDIN pin end of the main control MCU analog-to-digital conversion unit 1; the VSS end of the simulation debugging interface 5 is connected to the VSS end of the main control MCU analog-to-digital conversion unit 1, and the VDD end of the simulation debugging interface 5 is connected to the VDD end of the main control MCU analog-to-digital conversion unit 1, so as to input driving power to the main control MCU analog-to-digital conversion unit 1; wherein, the SDI end, SDO end, SCE end, RC1 end and TX1 end of the main control MCU analog-to-digital conversion unit 1 are all connected to L ED1, LED2, LED3, LED4, LED5, each group of LEDs is connected to the main control MCU analog-to-digital conversion unit 1 through a 1k resistor, and the VDDA end of the main control MCU analog-to-digital conversion unit 1 is grounded through a 0.1u capacitor C1 and a 10u capacitor C2 respectively; the SCL end and the SDA end of the power digital signal output unit 4 are correspondingly connected to the SCL end and the SDA end of the main control MCU analog-to-digital conversion unit 1, the third pin end of the power digital signal output unit 4 is connected to a wire, one end of the wire is connected to the VCC voltage, and the other end of the wire is directly grounded to GND through a 10u capacitor C5, the fourth pin end of the power digital signal output unit 4 is directly grounded to GND, the SCL end of the power digital signal output unit 4 is also connected to a 1k resistor R6, and the other end of the resistor R6 is connected to the VCC voltage, the SDA end of the power digital signal output unit 4 is also connected to a 1k resistor R7, and the other end of the resistor R7 is connected to the VCC voltage.

[0058] Apply the two-point force measurement method to obtain the single-axis force point of the key for experimental testing. Figure 2 As shown, the test method is as follows: five measuring points Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ are marked on the body of the force-bearing plate 31, which are five experimental examples. A button is installed on the force-bearing plate 31, and the left side of the force-bearing plate 31 is used as the force calibration point A, and the right side of the force-bearing plate 31 is used as the force calibration point B. The left side A is calibrated with 1000gm, and the right side B is calibrated with 1000gm; then 200gm weights are placed at each of the five measuring points; a force-bearing point detection module with a high-precision ∑△ADC is used in conjunction with two groups of full-bridge sensors 3 to obtain the weight ratio relationship, and a counter 2 is used to obtain test data of different measuring points to accurately calculate the placement position of the weight, so as to determine at which position of the force-bearing plate 31 the pressed force is applied, that is, to determine the position of the force-bearing point.

[0059] Table 1 Test results of the single-axis force point of the key obtained by two-point force measurement

[0060]

[0061] Combined with Table 1, we can get: Weight1+Weight2=X=1000gm, and the data is obtained by conversion according to the mentioned formula, wherein the weight / unit gm obtained on the left and the weight / unit gm obtained on the right are both converted through the formula, VA1=284005, VA2=48942, VB1=43326, VB2=277078; combined with the above-mentioned second-order determinant, the calculated K1=0.003052745, K2=0.003069867. It can be seen from Table 1 that the method of obtaining the single-axis force point of the key through two-point force measurement can quickly and intuitively determine the specific position of the key force point, and obtain the size of the mechanical force exerted on the key when force is applied to the key at different positions, so as to check whether the key is subjected to uniform force during use and determine the service life of the key.

[0062] It should be noted that in Table 1, the data of 23BitADC is obtained by amplifying 128 times the ADC chip in the main control MCU analog-to-digital conversion unit 1; when calculated, if K1 is greater than K2, it means that the force point of the key is on the left side of the force plate 31; when K2 is greater than K1, it means that the force point of the key is on the right side of the force plate 31; when K1 is equal to K2, it means that the force point of the key is in the center of the force plate 31.

[0063] The method for obtaining the single-axis force point of a key by two-point force measurement can determine whether there is a key action and whether the key is under force by measuring the sum of the two full-bridge sensors 3 through high-precision ∑△ADC, and can quickly and accurately determine the position of the force point by measuring the force ratio of the two full-bridge sensors 3. The test data has a small error and is easy to operate. It can perform multi-point testing on the key, and it is convenient to press different positions of the key to obtain the force values ​​of the key at different force points, thereby realizing all-round force detection of the key, which is helpful to more accurately determine the pressure resistance and durability performance of the key.

[0064] It is particularly noted that the present invention adopts differential mode measurement, and its differential mode measurement is two common mode voltage signals, which generate a differential mode voltage for measurement, that is, four half-bridge sensors are used as support points to detect the force on the key; among the four half-bridge sensors, the common mode voltage signals output by two of the half-bridge sensors generate a differential mode voltage signal, that is, the force value of a full-bridge sensor 3 is Weight1, and the common mode voltage signals output by the other two half-bridge sensors generate a differential mode voltage signal, that is, the force value of another full-bridge sensor 3 is Weight2; wherein, the mentioned counter 2 adopts but is not limited to TMC7CX type or SMD type electronic counter; the mentioned LED lamp assembly 6 can check whether the LED lamp assembly 6 is reflective during the test process, so as to judge whether the key force plate is under force and whether the key force detection is performed normally; wherein, the LED lamp assembly 6 is a key signal output indication LED lamp when in use, and the LED lamp emits light when receiving the key signal.

[0065] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be understood that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or integrated; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components; among them, there are many ways of detachable installation, for example, it can be through the way of plug-in and snap-fit, for example, through the way of bolt connection, etc.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for obtaining the force point of a key single axis by two-point force measurement, characterized in that: The steps include: Four half-bridge sensors Cell1, Cell2, Cell3 and Cell4 are used to form two full-bridge sensors, and force plates are installed on the two full-bridge sensors; The two full-bridge sensors are connected to the force point detection module of the high-precision ∑△ADC to obtain a differential voltage ADC value output by each full-bridge sensor, which is the magnitude of the mechanical force received by the two half-bridge sensors. The force values ​​of the two full-bridge sensors are Weight1 and Weight2 respectively. Use the sum of Weight1 and Weight2, X, to determine whether there is a key press. The relationship is: X=Weight1+Weight2; The specific force point position on the single axis of the key is determined by the proportional relationship value Scale of Weight1 and Weight2. The proportional relationship value formula is: Scale=Weight1 / X or Scale=Weight2 / X; The common mode voltage of half-bridge sensor Cell2 is used as AI1, the common mode voltage of half-bridge sensor Cell1 is used as AI0, the common mode voltage of half-bridge sensor Cell4 is used as AI3, and the common mode voltage of half-bridge sensor Cell3 is used as AI2; Among them, the differential mode voltage ADC calibration value between AI0 and AI1 is K1, and the differential mode voltage zero point value between AI0 and AI1 is Z1; The differential mode voltage ADC calibration value between AI2 and AI3 is K2, and the differential mode voltage zero point value between AI2 and AI3 is Z2; Arrange half-bridge sensor Cell1 and half-bridge sensor Cell2 from top to bottom on the left side of the force-bearing plate, and use the left side of the force-bearing plate as force calibration point A. Arrange half-bridge sensor Cell4 and half-bridge sensor Cell3 from top to bottom on the right side of the force-bearing plate, and use the right side of the force-bearing plate as force calibration point B. When measuring the force calibration point A, the ADC value of the differential mode voltage between AI0 and AI1 is A1, and the ADC value of the differential mode voltage between AI2 and AI3 is A2. Its differential mode voltage VA1=A1-Z1, differential mode voltage VA2=A2-Z1; When measuring the force calibration point B, the differential mode voltage ADC value between AI0 and AI1 is B1, and the differential mode voltage ADC value between AI2 and AI3 is B2. Its differential mode voltage VB1=B1-Z1, differential mode voltage VB2=B2-Z1; Substitute the following formula to obtain the force values ​​of Weight1 and Weight2: Weight1=VA1*K1+VA2*K2, Weight2=VB1*K1+VB2*K2.

2. The method for obtaining the single-axis force point of a key by two-point force measurement according to claim 1, characterized in that: The force coefficients K1 and K2 of the two full-bridge sensors are obtained through the second-order determinant, and the second-order determinant is as follows: ， 。 3. The method for obtaining the single-axis force point of a key by two-point force measurement according to claim 1, characterized in that: The half-bridge sensor adopts a force sensor or a weighing sensor. A metal sheet is arranged on the half-bridge sensor, and two strain gauges are attached to the metal sheet.

4. The method for obtaining the single-axis force point of a key by two-point force measurement according to claim 1, characterized in that: The force point detection module comprises a main control MCU analog-to-digital conversion unit connected to four half-bridge sensors, and a power digital signal output unit is connected to the SCL pin end and the SDA pin end of the main control MCU analog-to-digital conversion unit.

5. The method for obtaining the single-axis force point of a key by two-point force measurement according to claim 4, characterized in that: A counter is connected to an output end of the main control MCU analog-to-digital conversion unit, and the counter is used to display 23-bit differential voltage ADC value data obtained by amplifying the voltage generated by the stress plate by 128 times by the main control MCU analog-to-digital conversion unit.

6. The method for obtaining the single-axis force point of a key by two-point force measurement according to claim 4, characterized in that: The input end of the analog-to-digital conversion unit of the main control MCU is connected to a simulation debugging interface, which adopts a 6P interface of HY_ICP 2.54, and the output end of the analog-to-digital conversion unit of the main control MCU is connected to an LED lamp assembly.

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