CN111782092A

CN111782092A - Non-contact type password keyboard input device and input method

Info

Publication number: CN111782092A
Application number: CN202010440360.9A
Authority: CN
Inventors: 孙滕谌; 张大华; 庄玮
Original assignee: Beijing Tashan Technology Co ltd
Current assignee: Beijing Tashan Technology Co ltd
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-10-16

Abstract

A non-contact keyboard device suitable for inputting bank password PAD and key position input method, including power supply circuit, capacitive sensor, capacitor digital conversion circuit, control module, state feedback control circuit and indicator, also include the electrode membrane attached to PAD, there is capacitor electrode of the key position of corresponding PAD on the electrode membrane, the capacitor electrode is connected to control module; the capacitive sensor comprises a first electrode arranged on the outer side of the periphery of the key position, a second electrode arranged on the periphery of the key position and a third electrode arranged in the center of the key position, wherein the second electrode and the third electrode are made of transparent materials; any electrode is at least double-key, and the third electrode sinks 0.8-3.5mm lower than the second electrode; each electrode is connected with a capacitance digital conversion circuit, and the capacitance digital conversion circuit is connected with the control module; the control module is connected with the state feedback control circuit and the indicator; according to the detection of the self-capacitance of each electrode, the three-dimensional position of the finger on the keyboard is determined, and thus the three-state response of the finger pointing to the key position is provided through a feedback control circuit and input; the invention provides a low-cost and mature CDC chip technology which has reasonable structural design and high resolution, effectively resists various interferences and fully utilizes capacitance detection, provides a commercialized non-contact input solution which can be popularized and popularized for sanitation sensitivity, and provides an interface protocol for a bank which is self-made and does not need to be kept secret.

Description

Non-contact type password keyboard input device and input method

Technical Field

The invention relates to public health keyboard buttons, in particular to a health sensitive induction button, and particularly relates to a matched non-contact password keyboard input device and an input method of a PAD (PAD application access) password device for inputting a password by a bank.

Background

The disinfection of elevators and the like, in particular of push-button switches, is faced with a huge workload and even difficult to achieve disinfection treatment of viruses, for which reason there is a need in the society for proximity sensing buttons, since push-button switches in the public area, such as buttons for elevator floor selection and door opening and closing, flush switches in toilets, public drinking water switches and the like, are liable to cause infectious diseases, whereas non-contact buttons can avoid such a risk.

For the approach of human body, especially the approach of fingers operating elevator buttons, there are many technical solutions that can be adopted, including camera, infrared or radio frequency technologies, such as chinese patent No. 201480079328.5; capacitive sensing is the least costly of the various sensing schemes.

Chinese patent 201480079328 discloses a technical scheme for controlling an elevator by using gestures, and in the specification, technologies like camera shooting are mentioned to record gestures, including preset gestures, and the main technical constitution is that the gestures are recorded or even customized, the data of the gestures are recorded in a system to form a gesture library, and then after a gesture command is detected, the gesture library is compared with the gesture library to judge the meaning of the gestures, which is somewhat similar to the existing technology of identifying human faces which are already popularized; the technology needs a lot of hardware equipment and is expensive, on the other hand, customization of a user is very difficult, because human gestures and action modes are strange, the technology has a considerable challenge in two contradictions of accurate judgment, identification and interference resistance, and the difficulty of the technology is indirectly explained by the product which does not appear in the market at present.

Application No. 201610551225.5, which proposes a capacitive proximity button with a groove, the capacitive proximity button is arranged at the bottom of the groove, and the proximity button can be triggered by the finger of the designer who has to extend into the groove through the threshold value, the application does not disclose a specific capacitance measurement method of the capacitive proximity button, the proposal has the defect that the finger of the user can easily touch the inner wall of the groove when extending into the groove, especially in the environment of elevator with relatively dim light and possibly crowded personnel, and meanwhile, the gesture-sensing user is unlikely to ensure that the finger of the action can be completely controlled without shaking, otherwise the significance of sanitation sensitivity is lost; on the other hand, the patent cannot avoid the influence of environmental factors such as temperature and humidity on the set threshold.

US7498822 discloses a capacitance sensing approach scheme for human fingers, and a similar concave-designed capacitance electrode is adopted, and the above problems are also existed, if trying to avoid the above problems, according to our experiments, the distance between the finger and the switch wall is required to be more than 2cm as the design basis, then the switch arranged on the concave electrode needs the inner diameter design of 5cm at least, so that the arrangement of a plurality of switch buttons of the elevator becomes a challenge; in addition, the patent discloses a technical scheme of measuring the capacitance by a simple analog circuit, and further, in order to eliminate mutual crosstalk, an equipotential method and a differential amplifier are specially adopted, but through repeated experiments, capacitance value change which can be generated by a human finger is about 10ff magnitude under a safe distance for preventing unintentional touch on one electrode designed under an elevator environment, a good effect is difficult to obtain between measurement and elimination of environmental influence by the simple analog circuit, and the required device cost is also high. In addition, the structure of the concave electrode arrangement will increase the complexity of the forming of the hovering button structure, cause the increase of the processing cost and affect the aesthetic appearance of the hovering button and the cleaning and disinfection work of the elevator in future. The US7498822 patent only adopts a method of measuring self capacitance, but excludes a method of measuring mutual capacitance, does not utilize the advantage of strong anti-interference capability of the mutual capacitance, improves the performance of the hover button, and in addition, the patent can cause confusion and inconvenience for an operator to use the hover button due to the absence of an acousto-optic feedback system necessary for the hover button.

In a capacitance digital conversion circuit (CDC) of the prior art, such as DAI7142 and ADI7147, a delta-sigma modulation method is adopted to directly convert a measured capacitance value into a digital value by charging and discharging the measured capacitance for a plurality of times and comparing the measured capacitance value with a reference capacitance (see US patent number: 5,134,401), so that the measurement sensitivity of the capacitance can be improved to 1ff level, the requirement of a measurement system on the measurement sensitivity of the capacitance under a safe distance can be easily met, and particularly, the design of chips has a plurality of channels, so that the circuit design is simple and convenient, and the cost and the installation difficulty are effectively reduced.

Compared with technologies such as a camera, infrared or radio frequency and the like, in the aspect of detecting human body approach, the capacitance detection technology has the characteristics of simple circuit structure, low cost and the like, but has the high requirement on detection resolution due to small capacitance change, and a capacitance detection electrode is easily influenced by the environment.

Generally, the self-capacitance formed by the capacitance electrodes and the mutual capacitance formed between the electrodes are influenced by approaching fingers, the influence is effectively utilized, different characteristics of self-capacitance measurement and mutual capacitance measurement are considered to detect the approach degree of the fingers, and the influence of other parts of a body, misoperation and environment on the electrode capacitance measurement is synchronously eliminated, so that the influence is not easy at present.

For the hovering button adopting the capacitor to sense the approach of the human fingers, different sensing habits of a user need to be fully considered, meanwhile, the accurate judgment needs to be made by preventing the sensing of other parts of the body and the false triggering caused by the action of a cleaner during cleaning, and under the environment of an elevator, the accurate judgment is quite difficult, so that no commercialized product is found so far.

Based on the problems of these prior art, we have developed a hovering capacitive sensor and applied for a patent, application No. 202010287562.4, and the product is also put into mass production preparation.

However, for the small keyboard with about ten keys of entrance guard and vending machine, especially POS and ATM machine, because the size of each key is very small, even its layout is solidified, it is quite difficult to make a separate electrode for each key in this small size space, which can judge that the finger is close to but not in contact with, so despite the cost advantage of the capacitance sensor, although the capacitance-to-digital conversion circuit used in the capacitance sensor is quite mature, there is no non-contact commercial application in the small keyboard product with solidified size, and the requirement of hygiene sensitivity is more and more strong.

Chinese patent 201710893997 establishes four sensing electrodes around the display screen to detect the three-dimensional positioning of the fingers under non-contact, and although electronic means such as additional shielding electrodes and equipotential are adopted, in practice, the influence of the fingers and the palm behind the fingers on the electrodes and the influence of different angles of pointing actions of the human fingers are caused, so that the technical scheme cannot accurately position the fingers and cannot realize commercial application.

Chinese patent 201110130539 discloses a non-contact technical solution for a small keyboard with USB interface, which does not disclose how to construct the capacitive electrodes, but only discloses that a capacitive sensor is used to employ an induction sensor chip MC34940 of ciscail, which has 7 channels for measuring capacitance, and obviously cannot meet the requirement of at least ten numeric keypads for inputting passwords and the like.

The company has also developed a password keyboard non-contact input device of the ATM successfully, has also applied for Chinese patent No. 2020103455381, but in the course of commercial promotion, the data encryption meeting the bank system is difficult to open the practical difficulty to the society; in addition, the cipher device of the bank is continuously updated, the bank provides a PAD type cipher device for better confidentiality, the PAD type cipher device can randomly display numbers on a PAD, and the corresponding positions of the numbers are constant unlike a fixed keyboard, so that the confidentiality can be improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, create a capacitive sensor especially suitable for a non-contact keyboard button, and match with a mature capacitive-to-digital conversion technology, fully utilize the particularity of a CDC circuit on the immunity of stray distributed capacitors, adopt a measuring method combining self capacitance and mutual capacitance, and add a tri-state feedback indicating circuit, consider the characteristic of human finger approach, avoid various interferences, accurately judge the approach action of the finger to trigger the button, and easily accept the whole cost by commercialization, thereby being suitable for the non-contact type reconstruction of the existing PAD type password input device of banks and the like without invading the system of the original password setting.

The invention creates a non-contact keyboard capacitance sensor, which comprises a power circuit, a capacitance sensor, a capacitance digital conversion circuit, a control module, a state feedback control circuit, an indicator and a communication circuit, wherein the power circuit is connected with the capacitance sensor;

the capacitance sensor comprises a first electrode arranged on the outer side of the periphery of the key position, a second electrode arranged on the periphery of the key position and a third electrode arranged in the center of the key position;

the first electrodes comprise full-key-position transverse electrodes arranged up and down outside the peripheries of the key positions and at least two-key-position vertical electrodes arranged left and right outside the keyboard;

the second electrodes comprise at least two-key vertical electrodes at the left and right of the keyboard position and two-key electrodes transversely arranged up and down of the keyboard, and all the second electrodes are positioned in the same plane;

the third electrode is a central electrode of the keyboard center which forms a height difference of 0.8-3.5mm with the second electrode in the height direction;

the fourth electrode is arranged at the lower part of the third electrode, clings to the surface of the PDA when being installed, and is arranged to be in one-to-one correspondence with the key positions displayed on the PDA;

the capacitance digital conversion circuit comprises a capacitance excitation signal circuit, and the capacitance excitation signal circuit generates a high-frequency square wave excitation signal;

each electrode is connected with a capacitance digital conversion circuit, and the capacitance digital conversion circuit is connected with the control module; the control module is connected with the state feedback control circuit and the indicators, and the indicators are positioned on the corresponding key positions;

the control module

Outputting a trigger signal of the key button according to the fact that a human finger points to a quick trigger area above a certain key position and exceeds a specified time;

or outputting the triggering signal of the key button according to the fact that the residence time of the human finger pointing to the effective triggering area above a certain key position exceeds the set time and/or the virtual clicking action of the human finger in the effective triggering area above the certain key position.

Furthermore, the central electrode is a square or circular ring electrode occupying 2 x 2 key positions.

Or the central electrode is composed of electrodes occupying at least two key positions and distributed left and right or distributed up and down.

The first electrode and the second electrode are in the same plane.

Or the first electrodes are all obliquely arranged and lean against the upper part of the central electrode.

The first electrode further comprises another all-bonded electrode positioned at a lower position.

And an active shielding electrode is arranged below the first electrode, the second electrode and the third electrode, and the area of the active shielding electrode is not smaller than the orthographic projection area of the first electrode, the second electrode and the third electrode.

The method of the patent comprises the following steps: the input method of the non-contact keyboard comprises the capacitance sensor, and the self-capacitance values formed by all the electrodes of the first electrode, the second electrode and the third electrode and the fingers are periodically detected in a time-sharing manner along with the movement of the fingers above each key position of the keyboard;

in the determination of the key position pointed by the finger in the transverse direction, judging according to whether the ratio of two capacitance values is smaller than the transverse preset value of the key position, wherein the two capacitance values are used as the ratio of the capacitance value of the first electrode at the transverse farthest position to the capacitance value of the first electrode or the second electrode at the transverse closest position of the key position on the opposite side;

in the determination of the key position pointed by the finger in the longitudinal direction, the judgment is also carried out according to whether the ratio of two capacitance values is smaller than the longitudinal preset value of the key position, wherein the two capacitances are used as the ratio of the capacitance value of the first electrode which is farthest in the longitudinal direction to the capacitance value of the first electrode or the second electrode which is closest to the key position in the longitudinal direction on the opposite side;

judging whether the finger enters the effective triggering area or not according to whether the capacitance of the second electrode closest to the key position on the capacitance ratio of the central electrode is smaller than the height preset value of the key position or whether the capacitance ratio of the second electrode where the key position is located on the capacitance ratio of the central electrode is smaller than the height preset value or not;

if the finger is closer to the second electrode plane than the minimum of the effective trigger area, the user is considered to enter a fast trigger state: according to the key positions determined transversely and longitudinally, the controller lights the key position of the finger position to enter a pre-triggering state, continues to detect and calculate the self-capacitance value of each electrode, delays to judge whether the finger is still at the position, lights the confirming state if the finger is still at the position, and outputs a triggering signal of the key position;

otherwise, if the finger enters the active trigger area: according to the determined key position transversely and longitudinally, the controller controls the state feedback control circuit to light the indicator pre-triggered by the key position; once the finger leaves a certain key position and enters the next key position, the controller controls the state feedback control circuit to close the pre-triggered indicator of the left key position and light the indicator of the next key position where the finger enters; detecting and calculating the residence time of human finger pointing to the effective trigger area on the key position, judging whether the residence time exceeds the set time, and/or detecting and calculating the self-capacitance change of the electrode required by the finger key position to determine the transverse and longitudinal positions, judging that the finger has click action on the key position, and outputting the trigger signal of the key position by the controller.

After receiving the key position trigger signal of the controller, the analog switch grounds the electrode of the fourth electrode corresponding to the key position, thereby realizing the clicking action of the human hand on the key position, which is a simulated action.

In particular, the electrode arrangement and the operating method created by the invention have the following advantages: firstly, each key position adopts at least two key position electrode structure design, and the sensitivity in the vertical direction is improved by at least one time by improving the area of the key position electrode by at least one time, thereby effectively improving the minimum safety distance. The risk of virus propagation caused by the contact of fingers with key positions is fundamentally avoided; secondly, by a method of calculating the ratio of the transversely and longitudinally nearest adjacent second electrode to the farthest first or second electrode corresponding to each key position, the spatial resolution in the horizontal direction is effectively improved, so that the false triggering rate of the adjacent key positions of the keypad is greatly reduced, and the method is particularly suitable for matching with a pad cipher device; thirdly, the virtual click triggering method provided by the invention does not need to delay to wait for reaching the hovering time threshold, thereby effectively improving the hovering keypad input efficiency; fourthly, when the password is input, a method of combining quick triggering or hovering triggering and virtual clicking triggering input can be adopted, so that the safety is greatly improved, and fifth, the fourth electrode is arranged to replace the clicking action of a human finger in a mode of controlling grounding through an analog switch, so that the bank system does not need to be invaded, and the bank system does not have any commercialized resistance.

The control module may adopt an MCU, and with the continuous development of electronic technology, a chip combining a capacitance-to-digital conversion circuit CDC and a control module MCU appears, such as a PSoC 4100S Plus series of CYPRESS, but the functional composition is so.

Drawings

FIG. 1 is a schematic view of an inventive electrode arrangement, wherein FIG. 1-1 shows one embodiment of a center electrode in phantom; FIGS. 1-2 show, in phantom, a center electrode of another embodiment; 1-3 and FIGS. 1-4 again show circular and annular center electrode schemes; FIGS. 1-5 show schematic views of an arrangement in which the first electrode is arranged obliquely; FIGS. 1-6 disclose schematic diagrams of alternative arrangements of a first electrode having a total of two full key positions below;

FIG. 2 is a key layout diagram of the present invention corresponding to FIG. 1;

FIG. 3 is a schematic diagram of the input of the present invention with a finger pointing to a key;

FIG. 4 is a schematic diagram of the effective trigger area and the fast trigger area above the key position according to the present invention;

FIG. 5 is a logic diagram of the inventive method;

fig. 6 is a schematic diagram of the inventive circuit.

FIG. 7 is a schematic view of a finger entering key No. 6; wherein, FIG. 7-1 is a schematic diagram of a finger above the key No. 6, and FIG. 7-2 is a schematic diagram of a longitudinal section of the finger entering the effective triggering area of the key No. 6; FIG. 7-3 is a schematic cross-sectional view of a finger entering the effective triggering area of key No. 6;

FIG. 8 is a graph of capacitance change produced by a finger clicking within the active trigger area above the key location;

FIG. 9 relates to a schematic illustration of a fourth electrode;

FIG. 10 is a schematic diagram of a structure according to an embodiment.

FIG. 11 is a schematic diagram of an exemplary embodiment of electrodes, including the hierarchical diagram of FIG. 11-1, the layout and layout of the 1 st electrode and the 2 nd electrode of FIG. 11-2, the layout and layout of the 3 rd electrode of FIG. 11-3, and the layout and layout of the 4 th electrode of FIG. 11-4.

Detailed Description

For the PAD cipher device for bank to input cipher, at least ten number keys of 0-9, sometimes one confirmation key and double zero "00" key are needed, so that 12 keys of

3X

4 or 16 keys of 4X 4 are developed, and when 16 keys are not used, some keys are combined and combined into one. The present cipher device for inputting cipher code by PDA has fixed digital keyboard position for safety and its key value is randomly regulated each time. In view of this situation, the technical features of the present invention will be described in detail with the technical solution of 16 key positions in the schematic diagram.

Referring to fig. 1 and 2, with respect to the arrangement of the keys, fig. 2 shows 16 keys, labeled with numerals 1-16, and also shows the arrangement of the electrodes corresponding to the keys, which is consistent with the keys displayed on the PDA. Referring mainly to fig. 1, the non-contact keyboard capacitance sensor of the invention comprises a power circuit, a capacitance sensor, a capacitance-to-digital conversion circuit, a control module, a state feedback control circuit, an indicator and a communication circuit; wherein:

the capacitance sensor comprises a first electrode A-1/A-2/A-3/A-4/A-5/A-6 arranged outside the periphery of the key, a second electrode A-7/A-8/A-9/A-10/A-11/A-12 arranged around the key and a third electrode B-1 arranged in the center of the key;

the first electrode comprises full-key-position transverse electrodes A-1 and A-2 which are arranged up and down outside the key position periphery, and at least two-key-position vertical electrodes A-3/A-4 and A-5/A-6 which are arranged left and right outside the keyboard;

the second electrodes comprise at least two key position vertical electrodes A-7/A-8 and A-9/A-10 at the left and right of the keyboard position, and two key position electrodes A-11 and A-12 which are transversely arranged up and down the keyboard, and all the second electrodes are positioned in the same plane;

the third electrode B-1 is a central electrode of the keyboard center which forms a height difference of 0.8-3.5mm with the second electrode in the height direction;

with reference to the schematic diagram of fig. 6, the capacitance-to-digital conversion circuit CDC itself comprises a capacitance excitation signal circuit that generates a high-frequency square wave excitation signal;

the electrodes a-1 to a-12 and B-1 are divided into a first electrode 1 (electrodes a-1 to a-6), a second electrode 2 (electrodes a-7 to a-12) and a third electrode 3 (electrode B-1), and are connected to a capacitance digital conversion circuit CDC, and the capacitance digital conversion circuit CDC is connected to the control module, in the industry, the control module may adopt MCU, and with the continuous development of electronic technology, a chip 6 combining the capacitance digital conversion circuit CDC and the control module MCU into one appears, such as PSoC 4100S Plus series of CYPRESS, but the functional composition is so.

The control module is connected with the state feedback control circuit 5-3 and the indicator, the indicator is positioned on each corresponding key position, the indicator is not shown in the figure, under the prior art, the best scheme is to install LED lamps displaying two states or three states with different colors in the key position or nearby, and the LED lamps can also be arranged on the frame;

referring to fig. 3 to 7, the control module MCU outputs the trigger signal of the key button according to the human finger pointing to the fast trigger area 2-2 above a certain key and exceeding the specified time; or, outputting the triggering signal of the key button according to the fact that the residence time of the human finger pointing to the effective triggering area 2-1 above a certain key position exceeds the set time and/or the virtual clicking action of the human finger in the effective triggering area 2-1 above the certain key position;

the so-called trigger signal is that the controller grounds the key position electrode corresponding to the transparent fourth electrode, and simulates the clicking action of a human hand on the traditional PAD password input screen.

FIG. 4 schematically shows the upper sensing area of the keyboard divided into an active triggering area 2-1 and a fast triggering area 2-2, i.e., closer to the surface of the key than the active triggering area, even to the point of being immune to the risk of viral infection; the effective triggering area is a height range which is set according to the requirement of the keyboard and is away from the surface of the keyboard, for example, a height layer which is 6-35mm away from the surface of the second electrode, the elimination of the virus infection risk is mainly considered, and the habit that a user can control the movement of the finger of the user is set according to factors such as the resolution of the electrode sensing finger movement.

Referring to the various schematic views in fig. 1, the center electrode B-1 may be a square electrode (fig. 1-1) or a circular (fig. 1-3) or circular (fig. 1-4) electrode occupying 2 x 2 of the bond; the central electrode B-1 may also be composed of two electrodes distributed left and right, as shown in fig. 1-2, but of course, the central electrode may also be composed of electrodes distributed up and down and occupying at least two key positions.

In general, the first electrodes A-1 to A-6 are in the same plane as the second electrodes A-7 to A-12, but for better detection of a finger above each key position, the first electrodes A-1 to A-6 are all obliquely mounted toward the top of the central electrode, see FIGS. 1-5.

Because the size of the keyboard is solidified or limited, and the resolution requirement of the capacitance sensor to human fingers is considered, the invention adopts at least two-key electrode arrangement besides arranging the first electrode except the key position and the third electrode sinking for a certain distance, can meet the requirement of resolution, and then considers the influence of the palm of the finger on the position of the finger detected by the capacitance sensor and the general use habit of the user, adopts the topological arrangement of the key position electrodes as shown in figure 1, because the user generally extends the finger to point out each key position of the non-contact keyboard, the human body part with the palm located below, sometimes much larger than the fingers, poses a challenge to the first electrode a-2 below, for which purpose, in order to effectively detect and eliminate the effect of the palm, an electrode C-1 (see FIGS. 1-6) is additionally provided at the lower portion of the first electrode A-2.

For the input method of the non-contact keyboard, based on the capacitance sensor formed by the electrodes of various schemes introduced above, the self-capacitance values formed by all the electrodes of the first, second and third electrodes and the fingers are periodically detected in a time-sharing manner along with the movement of the fingers above the key positions of the keyboard; referring to fig. 7, when a human finger is located above the number 6 key and enters the effective trigger area 2-1 of the number 6 key, the finger is periodically scanned in a time-sharing manner to enter the effective trigger area, and the position of the finger in the X, Y axis direction in the keyboard can be found from the threshold table by calculating the self-capacitance ratio of each electrode plate of the first electrode, the second electrode and the third electrode. 7-2, and 7-3, the ratio of the self-capacitance C5 formed by the finger and the first electrode A-5 farthest in the X-axis direction (transverse direction) to the self-capacitance C7 formed by the first or second electrode A-7 nearest in the opposite direction meets the requirement in the threshold table, and the ratio of the self-capacitance C2 formed by the finger and the first capacitor plate A-2 farthest in the Y-axis direction (longitudinal direction) to the self-capacitance C11 formed by the first or second electrode A-11 nearest in the opposite direction meets the requirement in the threshold table, so that the finger can be determined to be located at the X-axis and Y-axis positions of the keyboard, i.e., the finger can be determined to be located at key position No. 6.

Therefore, in the non-contact keyboard of the invention, in the determination of the key position pointed by the finger in the transverse direction, the judgment is carried out according to whether the ratio of two capacitance values is smaller than the transverse threshold value of the key position, wherein the two capacitance values are used as the ratio of the capacitance value of the first electrode farthest in the transverse direction to the capacitance value of the first electrode or the second electrode closest to the key position in the transverse direction on the opposite side;

if the finger is closer to the second electrode plane than the minimum of the effective trigger area, it is considered that the user enters the fast trigger area 2-2 and needs to enter the fast trigger state: according to the key positions determined transversely and longitudinally, the controller lights the key position of the finger position to enter a pre-triggering state, continues to detect and calculate the self-capacitance value of each electrode, delays to judge whether the finger is still at the position, lights the confirming state if the finger is still at the position, and outputs a triggering signal of the key position;

otherwise, if the finger enters the active trigger area 2-1: according to the determined key position transversely and longitudinally, the controller controls the state feedback control circuit to light the indicator pre-triggered by the key position; once the finger leaves a certain key position and enters the next key position, the controller controls the state feedback control circuit to close the pre-triggered indicator of the left key position and light the indicator of the next key position where the finger enters; detecting and calculating the residence time of a human finger pointing to an effective trigger area on the upper part of a certain key position, judging whether the residence time exceeds the set time, and/or detecting and calculating the self-capacitance change of an electrode required by the finger at least for determining the transverse longitudinal position of the key position, judging that the finger has a clicking action on the certain key position, outputting trigger signals of the key position by a controller, and judging according to the trigger of the finger after the finger is determined to be in an X/Y/Z three-dimensional space on a keyboard, and referring to a flow chart of fig. 5.

In FIGS. 7-2 and 7-3, not only the height difference Δ d between the second and third electrodes B-1, but also the height d1 of the finger from the second electrode, the height d2 of the finger from the third electrode, the minimum height dmin (0.5CM) of the effective levitation region, the maximum height dmax (2CM) of the levitation region, and the minimum safety distance dsaf (1CM) are shown. In the elevation direction, below the distance dmin is a fast trigger region, and the range between dmax and dmin is a valid trigger region.

In addition to the fact that the CDC in the prior art can measure the self-capacitance of each electrode after being connected into the electrodes, the CDC can also measure the mutual capacitance formed between the two electrodes, and because the mutual capacitance is relatively difficult to be interfered by factors such as the environment and the like, the height d1 of a finger on a keyboard can be accurately measured, and only the measurement range is relatively limited.

After the finger is determined to be above the key position, the key position is triggered by three schemes, one scheme is that the finger enters a quick trigger area to trigger, the other scheme is that the finger hovers for a certain set time in an effective trigger area to trigger, the general hovering time is set between 0.5 and 2 seconds, and the optimal hovering time is 0.5 to 1 second; the third is that the finger performs one-time clicking action in the effective triggering area, namely triggering by virtual clicking of the key position.

The control module is connected with a feedback control circuit, the feedback control circuit controls an indicator to be in three states of no trigger, pre-trigger and trigger, the indicator can be a sound in places without confidentiality requirements, and LED indicator lamps arranged on a keyboard or around each key position of the keyboard better conforming to confidentiality habits.

The whole non-contact keyboard can be manufactured by adopting the structure shown in fig. 9 and fig. 10, wherein the keyboard panel 6-1 can be manufactured by adopting a plurality of layers of conductive films, the first electrode 1, the second electrode 2, the third electrode 3 and the 4 th electrode 4 can be manufactured by adopting transparent conductive materials such as ito, PEdot and the like on different layers of the plurality of layers of conductive films and connected onto the control board 6-4, and the transparent suspended keyboard module is finally formed by fixing the structure shell 6-3. As shown in fig. 11-1, the keyboard panel is made of 4 layers of transparent ITO films, 6-1-1, 6-1-7 are top and bottom protective layers, and can be made of ultra-thin toughened glass adhesive films, 6-1-3, 6-1-6 are all flexible transparent circuit substrate layers, and can be made of PET substrates, the top surface of PET label 6-1-3 is a circuit layer 6-1-2, on which the first electrode and the second electrode circuit shown in fig. 11-2 are drawn. The third electrode circuit shown in the figure 11-3 is drawn on the bottom surface of the 6-3-2, and the 4 th electrode circuit shown in the figure 11-4 is drawn on the back surface of the 6-1-5pet so as to realize the click action of the virtual human finger. The circuit layer can be made of ITO or PEDOT or other transparent conductive materials. The circuit can be drawn by silk-screen or laser etching.

The transparent suspension keyboard module can be fixed on the existing liquid crystal screen 6-8 in a bonding or electrostatic adsorption mode, and the shell 6-3 of the structure for strengthening strength can be designed into a clamp mode to be clamped on the frame of the liquid crystal screen. The 4 th electrode 4 can be designed according to the key position displayed on the screen, the 4 th electrode is required to be ensured to be coincident with the prior key position when being installed, or the 4 th electrode 4 is designed by adopting a row-column array mode, and the key position on the prior liquid crystal screen is adjusted and aligned by software after being installed. When the user uses the LCD screen, the user can see the key position displayed on the LCD screen through the transparent floating keyboard, when the finger of the user hovers on the key position, the position of the finger of the user is judged through the first electrode 1, the 2 nd electrode 2 and the 3 rd electrode 3, and after the key position pointed by the hand of the user is determined, the 4 th electrode 4 corresponding to the key position is controlled to be grounded through the analog switch S1 by referring to the figure 6, so that the touch function is realized by replacing the finger of the user. According to the scheme, the transparent hovering keyboard is used for replacing a human body finger to contact the liquid crystal screen, the installation is convenient, the cost is low, and the applicability is strong.

In general, 16 of the above-mentioned key positions may have surplus, then can compound two key positions into one; for the scheme that only 12 keys are enough, the electrode design is the same as that of the figure 1-1, and only the

keys

9, 10, 11 and 12 in the figure 2 are vacant, namely the third row is vacant, so that the detection of the fourth row of the first row, the second row and the fourth row is more accurate.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A non-contact password keyboard input device comprises a power circuit, a capacitance sensor, a capacitance-to-digital conversion circuit, a control module, a state feedback control circuit and an indicator; the method is characterized in that:

the second electrode and the third electrode are made of transparent materials;

the surface of the bank password input PAD is covered with a transparent fourth electrode film, the electrodes on the film are arranged corresponding to the key positions on the PAD, and the control module is connected with the transparent fourth electrode;

the control module grounds the transparent fourth electrode corresponding to the key position according to the following conditions:

according to the fact that a human finger points to a quick trigger area above a certain key position and exceeds a specified time;

or, according to the fact that the residence time of the human finger pointing to the effective triggering area above a certain key position exceeds the set time, and/or the virtual clicking action of the human finger in the effective triggering area above the certain key position.

2. The non-contact password keyboard input device of claim 1, wherein the center electrode is a square or circular ring electrode occupying 2 x 2 key positions.

3. The non-contact password keyboard input device of claim 1, wherein the center electrode is composed of electrodes occupying at least two keys distributed left and right or up and down.

4. The contactless passkey input device of claim 1, wherein the first electrode and the second electrode are coplanar.

5. A touch-less combination keypad input device as in claim 1, wherein the first electrodes are each mounted obliquely toward the top of the center electrode.

6. The contactless password keyboard input device of claim 1, wherein the first electrode further comprises another full-key electrode located at a lower position.

7. The input device of claim 1, wherein the control module is connected to the fourth electrode through an analog switch.

8. A non-contact keyboard input method, which comprises the capacitance sensor of any one of claims 1-7, and is characterized in that the self-capacitance value formed by all the electrodes of the first, second and third electrodes and the finger is periodically detected in a time-sharing manner along with the movement of the finger above each key position of the keyboard;

if the distance of the finger from the second electrode plane is closer to the electrode plane than the minimum value of the effective trigger area, it is considered that the user enters the fast trigger area and needs to enter the fast trigger state: according to the key positions determined transversely and longitudinally, the controller lights the key position of the finger position to enter a pre-triggering state, continues to detect and calculate the self-capacitance value of each electrode, delays to judge whether the finger is still at the position, lights the confirming state if the finger is still at the position, and outputs a triggering signal of the key position;

otherwise, if the finger enters the active trigger area: according to the determined key position transversely and longitudinally, the controller controls the state feedback control circuit to light the indicator pre-triggered by the key position; once the finger leaves a certain key position and enters the next key position, the controller controls the state feedback control circuit to close the pre-triggered indicator of the left key position and light the indicator of the next key position where the finger enters; detecting and calculating the residence time of the human finger pointing to the effective trigger area on the upper part of a certain key position, judging whether the residence time exceeds the set time, and/or detecting and calculating the self-capacitance change of the electrode required by the finger key position to determine the transverse and longitudinal positions, judging that the finger has clicking action on the certain key position, and grounding the capacitance electrode corresponding to the key position in the fourth electrode by the controller.

9. The input method as claimed in claim 8, wherein the capacitance-to-digital conversion circuit detects mutual capacitance between the center electrode and the second electrode where the key is located, for determining whether a finger of a human body enters the fast triggering area.

10. The input method according to claim 8, said hover time being between 0.5 and 2 seconds, the optimal hover time being 0.5-1 second.

11. The input method as claimed in claim 8, wherein the control module is connected to a feedback control circuit, and the feedback control circuit controls the indicator to assume three states of no trigger, pre-trigger and trigger.