CN214544274U

CN214544274U - Detection circuit for improving sensitivity of touch key

Info

Publication number: CN214544274U
Application number: CN202022959817.5U
Authority: CN
Inventors: 张善辉
Original assignee: Shenzhen Feiyi Technology Co ltd
Current assignee: Shenzhen Feiyi Technology Co ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-10-29
Anticipated expiration: 2030-12-11

Abstract

The utility model discloses an improve detection circuitry of touch button sensitivity, concretely relates to capacitanc touch button detection circuitry technical field, this detection circuitry include inductive electrode, multiplexer, measuring circuit, reference capacitance, CPU and output circuit, the inductive electrode includes 3 at least electrode slices, the inductive electrode passes through the multiplexer and is connected with measuring circuit, and measuring circuit data is read by CPU, through output circuit output data after the CPU operation. The utility model discloses a can improve detection circuitry of touch button sensitivity in applications such as draw runner gyro wheel, can calculate the coordinate of finger in whole response electrode fast, circuit structure is simple, and is with low costs, and it is convenient to install, and sensitivity is high, occupies fewly to the MCU resource, and the continuous long-time work low power dissipation, data are accurate.

Description

Detection circuit for improving sensitivity of touch key

Technical Field

The utility model relates to a touch button detects technical field, more specifically says, the utility model relates to an improve detection circuitry of touch button sensitivity.

Background

With the development of society and electronic technology, the touch keys are required to be various in shapes, particularly circular ring-shaped and strip-shaped slide bar touch keys, in the fields of chemical industry, medicine, automobiles, agriculture, household appliances and the like, and are required to be high in sensitivity and stable in performance. Similar applications are achieved with existing technologies: photoelectric sensing, mutual capacitance acquisition and independent touch of the keys are realized.

When the photoelectric sensing technology is used for detecting the slide bar key, the detection success rate is low, a transparent material is required to be used for a surface covering material, the surface covering material is sensitive to ambient light, and the situation that the surface covering material cannot be identified when the ambient light is strong can occur.

The slider key detection is carried out by utilizing a mutual capacitance acquisition mode, the circuit structure is complex, the cost is high, the power consumption of the circuit is high, and the slider key detection device cannot be applied to occasions with high sensitivity.

The slide bar key detection is carried out by using a single touch key mode, the circuit and the algorithm are relatively simple, but the slide bar key detection method cannot be applied to the condition that the requirement on the thicker sensitivity of a covering panel is high, or the high resolution cannot be realized (the resolution can be realized by small touch movement).

SUMMERY OF THE UTILITY MODEL

In order to solve the problems that in the prior art, when the slide bar key is detected, the cost is high, the circuit wiring is inconvenient, the requirement on a surface covering material is high, and the like, the slide bar type touch key detection circuit is improved.

In order to achieve the above object, the utility model provides a following technical scheme: the detection circuit comprises an induction electrode, a multiplexer, a measurement circuit, a reference capacitor, a CPU and an output circuit, wherein the induction electrode comprises at least 3 electrode plates, the induction electrode is connected with the measurement circuit and the CPU through the multiplexer, the CPU is connected with the output circuit, and the measurement circuit is connected with the reference capacitor.

In one embodiment, the electrode pads are at least 3 conductive electrode pads.

In one embodiment, the detection circuit includes a multiplexer, and the multiplexer can select a plurality of sensing electrodes and can be combined arbitrarily.

In one embodiment, each sensing electrode is in the shape of a strip or a ring with a center width of 3 mm.

The utility model discloses a technological effect and advantage:

by adopting the detection method of the detection circuit of the touch key, the detection of the current finger coordinate of the annular or strip-shaped touch key is realized by the detection circuit and the method, the detection is not influenced by the color of the surface covering material, the coordinate acquisition can be accurately realized when the thickness of the surface covering material reaches more than 10mm, and the false operation is not generated; the single induction electrode can be made very small, so that under the condition of the same slide bar length or the same diameter of a circular ring, the resolution can be improved by a plurality of times compared with the case of using a large-area electrode; after the method is used, the system can realize the high-resolution and high-sensitivity slide bar identification without adopting a special expensive high signal-to-noise ratio detection circuit, and the detection circuit and the method have the characteristics of high precision, low cost, continuous long-time work, low power consumption, simple circuit structure and the like.

To sum up, the utility model has the advantages that realize the effect of high sensitivity, high accuracy, low cost, low-power consumption through this detection method.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic block diagram of a detection circuit for improving the sensitivity of a touch key according to an embodiment of the present invention;

fig. 2 is a schematic view of a circular ring-shaped slide button plate according to an embodiment of the present invention;

fig. 3 is a schematic view of a strip-shaped slide bar key sheet according to an embodiment of the present invention;

fig. 4 is a control flow chart of a slide bar type touch key detection circuit and method according to an embodiment of the present invention.

The reference signs are: 1 induction electrode, 2 multiplexer, 3 measuring circuit, 4 reference capacitance, 5CPU, 6 output circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention provides a detection circuit for improving sensitivity of a touch key, where the detection circuit includes an inductive electrode 1, a multiplexer 2, a measurement circuit 3, a reference capacitor 4, a CPU5 and an output circuit 6, the inductive electrode 1 includes at least 3 electrode plates, the electrode plates are metal electrode plates, the electrode plates are in a shape of a long strip or a circular ring, and when the detection circuit is operated by a user, the detection circuit can directly touch the inductive electrode and can also be separated from other shells made of materials, such as organic glass and acrylic. When touch capacitance detection is carried out, a mode of combining adjacent electrodes is adopted, the induction area is increased, and the sensitivity is improved.

The detection circuit includes a multiplexer 2, and the multiplexer 2 can select a plurality of sensing electrodes 1 and can be arbitrarily combined.

The induction electrode 1 is connected with a measuring circuit 3 and a CPU5 through a multiplexer 2, the CPU5 is connected with an output circuit 5, and the measuring circuit 3 is connected with a reference capacitor 4.

In this embodiment, the detection circuit includes a switching value output, an LED output and a single bus output mode, so that the main control system can query the current finger coordinates.

In the present embodiment, the center width of each sensing electrode is 3 mm.

Preferably, the detection method further comprises performing certain logic judgment by software.

The detection method is characterized in that the area of each induction electrode is increased by collecting the capacitance of adjacent combination of the induction electrodes, so that the change value of the capacitance is increased, and stable detection can be realized under the condition of small electrodes and thick shells. And calculating the finger coordinates through software and outputting the finger coordinates, so that the main system can judge the finger displacement direction and the displacement. The utility model discloses can calculate the coordinate of finger in whole response electrode fast, circuit structure is simple, and is with low costs, and it is convenient to install, and sensitivity is high, and the continuous long-time work low power dissipation, data are accurate.

Make a slide bar touch key detection example in combination with the key layout of fig. 2, as shown in fig. 2, total 12 touch-sensitive electrodes, the central width 4mm of every electrode, use the utility model discloses detection method can support 24 coordinate discernments.

The circuit of the embodiment also comprises a reference capacitor, the capacitance value of the reference capacitor is related to the sensitivity, and the capacitor must use a material with smaller constant temperature drift coefficient of terylene and NPO.

In this embodiment, the touch power supply portion needs special processing to ensure that the VDD power supply ripple is less than 100mV during touch operation.

In this embodiment, the user can directly contact the electrode on the ring and also cover the surface material, and it should be noted that, due to the requirement of sensitivity, the thickness of the surface covering material can reach 10mm when the surface covering material is glass, and the thickness of the surface covering material can reach 8mm when the surface covering material is acrylic.

In this embodiment, the lengths of the wires from the electrode plates to the touch acquisition ports should be equal to each other as much as possible, and the wires cannot intersect with each other.

The embodiment for detecting the finger coordinates of the circular touch keys comprises the following steps:

s1: powering on the system and initializing each module and port;

s2: initializing and storing capacitance data of each induction electrode when no operation is performed;

s3: the multi-channel selector simultaneously selects the K1 and K2 induction electrodes, the area of the detected key is equivalent to that of a K1 electrode and a K2 electrode, and the sensitivity is extremely improved;

s4: opening a touch capacitance detection module, and waiting for the current sensing data to be detected and stored;

s5: the next combination (K2+ K3, K3+ K4 …) of sensing electrodes is selected by a multiplexer, and the adjacent combination mode is adopted to improve the sensitivity;

s6: waiting for the current capacitance data of all the induction electrode combinations to be acquired;

s7: comparing the reference value stored by the system to obtain the induction electrode with data change;

s8: and calculating current finger coordinates according to the obtained result, wherein for example, the capacitance change data of K1+ K2 and K2+ K3 are equivalent and reach a trigger threshold, the current finger coordinate is known to be K2 after averaging, if only K2+ K3 reaches the trigger threshold, the finger coordinates are known to be K2+ K3 and …, and so on, and the cycle combination of K1+ K12 is added, so that all 24 coordinates can be calculated in total.

S9: sending the current position coordinate information to an output circuit for a main system to inquire;

s10: and maintaining the current reference value data, and restarting the next detection after waiting for a scanning period specified by the system.

In this case, the acquirable resolutions are different according to different reference capacitance values, and in the case that the reference capacitance value is appropriate, although a single touch electrode is small, 2 or more adjacent electrodes are combined by adopting a combined electrode method, even under the condition that a common touch detection circuit is used and the signal-to-noise ratio of the detection circuit is not improved, the minimum capacitance variation of about 0.05pF on the single electrode can be acquired.

The current finger coordinate detection of the annular or strip-shaped touch key is realized, the detection is not influenced by the color of the surface covering material, the coordinate acquisition can be accurately realized when the thickness of the surface covering material reaches more than 10mm, and the misoperation is avoided; the detection circuit has the advantages that high accuracy is achieved, meanwhile, the detection circuit is not required to have a very high signal-to-noise ratio, the requirement for detecting hardware inside a chip is lowered, low cost is achieved, meanwhile, continuous long-time working power consumption is low, and the circuit structure is simple.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A detection circuit for improving the sensitivity of a touch key is characterized in that: the detection circuit comprises an induction electrode, a multiplexer, a measurement circuit, a reference capacitor, a CPU and an output circuit, wherein the induction electrode comprises at least 3 electrode plates, the induction electrode is connected with the measurement circuit and the CPU through the multiplexer, the CPU is connected with the output circuit, and the measurement circuit is connected with the reference capacitor.

2. The detection circuit for improving the sensitivity of a touch key according to claim 1, wherein: the electrode plates are at least 3 conductive electrode plates.

3. The detection circuit for improving the sensitivity of a touch key according to claim 1, wherein: the detection circuit comprises a multiplexer, and the multiplexer can select a plurality of induction electrodes and can be combined randomly.

4. The detection circuit for improving the sensitivity of a touch key according to claim 1, wherein: each induction electrode is in a strip shape or a circular ring shape, and the central width of each induction electrode is 3 mm.