CN111573457B

CN111573457B - Hover button sensor unit and method for providing trigger of hover button

Info

Publication number: CN111573457B
Application number: CN202010287562.4A
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: 2020-04-13
Filing date: 2020-04-13
Publication date: 2021-09-24
Anticipated expiration: 2040-04-13
Also published as: CN111573457A

Abstract

A hover button sensor unit, comprising: the device comprises a power circuit, a capacitance sensor, a capacitance digital conversion circuit, an MCU, an acousto-optic feedback control circuit and a communication circuit; the capacitance sensor is a central electrode and a peripheral electrode which are arranged in a convex shape, a capacitance digital conversion circuit measures the self capacitance and mutual capacitance of the central electrode and the peripheral electrode after the approach of a human finger, calculates and judges whether the finger enters an area range and the retention time, and outputs a control logic signal of the button by the control module; by means of a button formed by the sensor unit, the human body finger is detected to approach the effective hovering triggering area range on the upper part of a certain central electrode, and the tri-state response that the human body finger enters the effective hovering triggering area range on the upper part of the certain central electrode is provided through the acousto-optic feedback control circuit; the invention provides a low-cost and mature CDC chip technology which has reasonable structural design, effectively resists various interferences and fully utilizes capacitance detection, and provides a commercialized technical solution which can be popularized and popularized for sanitation sensitivity.

Description

Hover button sensor unit and method for providing trigger of hover button

Technical Field

The invention relates to a button for public health, in particular to a sensing button considering the sensitivity to the public health, such as a faucet, a flushing button of a water closet, a waterproof button of a water boiler and the like, and particularly relates to a button design of an elevator.

Background

The emergence of new coronary pneumonia epidemic situation, and the circumstances such as seasonal influenza present, to the disinfection of elevator, especially button switch's disinfection, face huge work load, even difficult realization virus's disinfection treatment, for this reason the demand to the proximity sensing button appears in the society, because the button switch of direct contact public area, for example the button of elevator floor selection and switch door, the bath switch of bathroom, public drinking water switch etc. lead to infecting the communicable disease easily, and non-contact button can avoid such 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.

For the photoelectric sensing faucet which is used in a large amount in the public area at present and the human body sensing control of the flush toilet, besides the high cost of the sensing controller, the problems that the sensing faucet is difficult to control at will exist, for example, when clothes are washed and faces are washed by towels, the sensing faucet is difficult to work normally, and a user needs a sensing control technology which is very close to the control of the physical faucet.

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 the capacitance detection is very easily influenced by the environment.

Generally, the self-capacitance formed by the capacitance electrodes and the mutual capacitance formed by the electrodes are influenced by approaching fingers, the influence is effectively utilized, different characteristics of self-capacitance measurement and mutual capacitance measurement are considered at the same time 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.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, create a capacitive sensor particularly suitable for the characteristics of a hovering button, and match with a mature capacitance-to-digital conversion technology, fully utilize the special characteristic of a CDC circuit for immunity to stray distributed capacitance, adopt a measurement method combining self capacitance and mutual capacitance, and add a tri-state acousto-optic feedback circuit, consider the characteristic of human finger approach, avoid various interferences, and accurately judge the approach action of the finger to trigger the button. The invention creates a capacitive sensor unit corresponding to a button, a hover button sensor unit, comprising: the device comprises a power circuit, a capacitance sensor, a capacitance digital conversion circuit, a control module, an acousto-optic feedback control circuit and a communication circuit;

the capacitance sensor is composed of one or more groups of electrodes, each group of electrodes comprises at least one central electrode and at least one peripheral electrode arranged around the central electrode, and the central electrode protrudes out of the peripheral electrode by 1.0-8.9 mm;

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;

the central electrode and the peripheral electrode are both connected with a capacitance digital conversion circuit, and the self capacitance and the mutual capacitance of the group of central electrode and the peripheral electrode after the approach of the human body finger is sensed are detected;

the capacitance digital conversion circuit is connected with the control module, and the control module outputs a trigger logic signal of the button according to the range of the effective hovering trigger area pointed by the human finger to the upper part of the central electrode and the residence time in the range.

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

Meanwhile, on the basis of the sensor unit, the button triggering method of the invention detects and calculates that the human body finger enters an effective hovering triggering area on the upper part of a certain central electrode through the capacitive sensor, and provides pre-triggering response of the human body finger entering the effective hovering triggering area through the acousto-optic feedback control circuit;

if the human finger enters a quick trigger area which is closer to the central electrode than the effective hovering trigger area, directly outputting a trigger logic signal of a button pointed by the human finger and simultaneously giving a trigger state response to an acousto-optic feedback control circuit; if the touch control signal is the touch control signal, the sound-light feedback control circuit gives a touch control signal to the touch control signal, and if the touch control signal exceeds the preset hovering time, the touch control signal is output to the touch control signal; and if the finger is detected to leave the effective hovering trigger area within the set hovering time, returning to the triggerless state.

In particular, the electrode arrangement created by the invention has the following advantages: firstly, the risk of finger contact with the side wall is fundamentally avoided; secondly, the safe distance of the side wall is not required to be considered, so that the diameter of the hovering button is effectively reduced, the outer diameter of the whole button can be controlled below 3CM, and the space layout requirement of multiple rows of buttons can be easily met; thirdly, the universal building block design is convenient for large-scale mass production; fourth, since fingers are not required to be inserted into the concave container, the surfaces of the multi-row convex structure hovering buttons can be uniformly decorated with a flat decoration material, such as glass, acryl or other non-conductive materials, and the convex structure itself can be realized with one or two layers of PCB boards at low cost.

Drawings

Fig. 1 is a schematic diagram of the use state of the invention, and also shows the approaching state of the finger relative to the button, and the solid line and the dotted line in the diagram respectively show different angle states of the human finger pointing to the button.

FIG. 2 is a perspective view of the sensor of the present invention, including FIG. 2-1, which is a schematic view of a human finger approaching a capacitive electrode in a horizontal direction; FIG. 2-2 is a schematic view of a human finger approaching a capacitive electrode at 45; FIGS. 2-3 are schematic diagrams of a human finger approaching a capacitive electrode in a vertical direction; fig. 2-4 are schematic diagrams of the human body's entire palm near the capacitive electrodes.

Fig. 3, including fig. 3-1 and fig. 3-2, shows the position relationship between the human fingers and palms and the capacitance electrodes and the embodied capacitance equivalent principle diagram during working, wherein fig. 3-2 shows the schematic diagram of the sensing range more clearly than fig. 3-1.

Fig. 4 is a structural diagram of the capacitive sensor under a single capacitive electrode unit created by the present invention, wherein fig. 4-1 shows the relationship of several capacitive electrodes in a plan view, and fig. 4-2 and 4-3 are schematic diagrams reflecting the arrangement of the capacitive electrodes in a section view.

Fig. 5 is a schematic view of the electrode arrangement of the invention involving more than one set of electrode units.

FIG. 6 is a schematic diagram of the timing of detecting the capacitor according to the present invention.

FIG. 7 is a schematic diagram of the capacitive electrode design in combination with other circuitry for a single button similar to that of FIGS. 4-2;

fig. 8 is an exploded view of an elevator up/down button/dual button base unit employing one expression structural arrangement created by the present invention.

Fig. 9 is a schematic diagram of capacitance electrode measurement and control created by the present invention.

Fig. 10 is a schematic diagram of the circuit configuration of the arrangement of multiple rows of buttons in an elevator.

Fig. 11 includes fig. 11-1, 11-2, 11-3, 11-4, 11-5, and 11-6, which are schematic diagrams of various configurations of the central electrode and the peripheral electrode, respectively.

FIG. 12 is a flow chart of the system for determining whether a finger is approaching.

FIG. 13, including FIG. 13-1, reflects the effect of the finger on the self-capacitance of the electrode and FIG. 13-2 gives the equivalent circuit at this time.

FIG. 14, including FIGS. 1 and 4-1, shows a schematic diagram of the effect of a finger on the mutual capacitance between two electrodes, and FIG. 14-2 shows an equivalent circuit at this time.

Detailed Description

The invention is suitable for the finger approach of the buttons in the hygiene-sensitive occasions to perform induction control, and the elevator buttons are mainly introduced in detail below, so that the technique achieved through the introduction is also suitable for other hygiene-sensitive button controls.

For the case of calculating and judging the approach of the finger to the electrode by using capacitance measurement, it is necessary to explain the case of self capacitance and mutual capacitance of the electrode, with reference to fig. 13 and 14; the principle of detecting the approach of a human body by using a capacitor can be divided into two modes of self-capacitance detection and mutual capacitance detection, the mutual capacitance detection principle refers to fig. 13-1, when the human body approaches, the electric field lines of the mutual capacitance Cm formed between two electrodes are disturbed by the human body to cause the capacitance value of the mutual capacitance Cm to change, the change is in direct proportion to the average distance between the two electrodes approaching the human body, an excitation signal is applied to one electrode, the other electrode is connected with a measuring circuit, the change value of the mutual capacitance can be detected, and the equivalent measuring circuit of the mutual capacitance detection circuit is shown in fig. 13-2, generally the mutual capacitance measuring distance is smaller, but the anti-interference capability is stronger; the principle of detection of self-capacitance is shown in fig. 14-1, when a human body approaches to a single electrode, a self-capacitance Cs is formed between the single electrode and the human body, the self-capacitance Cs is grounded through an equivalent capacitance Ca of the human body to the earth, Cs is proportional to the distance of the human body approaching to the single electrode, the equivalent capacitance Ca of the human body to the earth is about 200PF, the variation range of the self-capacitance Cs is usually less than 1PF, fig. 14-2 is an equivalent circuit for measuring the self-capacitance, it can be seen that Ca and Cs are in a series relation, according to a series capacitance formula, the equivalent capacitance Cx Ca Cs/(Ca + Cs) of the series capacitance is obtained, since Ca is much larger than Cf, the component Ca + Cs is about equal to Ca, so that Cx Ca is about equal to Ca/Cs, that the mutual capacitance Cs can be approximated to the capacitance of the single electrode to the earth, and therefore, the measurement of the self-capacitance Cs is equal to the measurement of the single electrode to the earth, the mutual capacitance is in direct proportion to the distance between the human body and a single electrode; the excitation signal of the self-capacitance and the measuring circuit are connected to the same electrode, and the self-capacitance measuring distance is longer, but the anti-interference capability is weaker; in contrast, the measurement distance of the mutual capacitance is relatively small, as influenced by the electrode arrangement, but its interference immunity is strong.

For the elevator buttons, the situation of one button is divided into three situations, namely the situation of one button, the situation of two buttons above and below the elevator, and the situation of a plurality of buttons in the elevator car;

for the user of the elevator, it is possible to trigger a certain button from different angles up, down, left and right by using a finger, in the application scene of the touch button switch, in parallel with the direction of the button, in the range of 360 degrees, the button should be triggered no matter the finger contacts the button from any direction, in the direction perpendicular to the button, the button should be triggered by the finger contacting the button from 0 to 90 degrees in any angle, and the hover button should also meet the requirement that the switch can be effectively triggered in the same direction and angle range as the touch button. Three states of human fingers approaching the button electrode are shown in fig. 1, including parallel entry shown by solid lines, 45 ° angle entry and vertical 90 ° angle entry shown by dotted lines, in which 4-1 is the button panel, 1-1 is the center electrode, and 1-2 is the peripheral electrode. The invention aims to enable the three finger approaching modes to be responded.

The hovering button needs to effectively prevent false triggering caused when a human body approaches the hovering button in a large area, including various false triggering situations that arms or backs of people in an elevator are close to or cling to the hovering button, and a palm or a fist is close to the hovering button during cleaning. To fully utilize the pointing action of extending a finger from the palm of a human body, the capacitive electrodes need to be designed with a considerable redundancy for distinguishing.

FIG. 2 is a schematic diagram of a human finger in three states to trigger a button and a schematic diagram of a palm proximity button, and the method for triggering a hover button of the present invention requires: the index finger is extended out, and the other 4 fingers are used for clenching the fist, and the action is also the normal pointing action of the fingers of the human body; as shown in FIG. 1, the center electrode may be approached at any angle in the range of 0 to 90 degrees in a direction perpendicular to the hover button, and may be approached at any angle in the range of 360 degrees in a direction parallel to the hover button. 2-1, 2-2, and 2-3 show the case where the finger approaches the hover button at 0 degree (horizontal), 45 degree, and 90 degree angles, respectively, perpendicular to the direction of the hover button, where the projected area S1 of the finger to the center electrode remains substantially constant over a range of 0 to 90 degrees, and the projected area S2 of the finger to the peripheral electrode remains substantially constant over a range of 0 to 45 degree angles, approximately 1/2 π r2 of the peripheral electrode area S21, where r2 is the radius of the peripheral electrode. The projected area S2 gradually increases over the range of 45 degrees to 90 degrees due to the influence of the remaining 4 fingers of the fist, reaching a maximum at 90 degrees, approximately 1/4 of the peripheral electrode area S21. On the premise that the distance d1 from the fingers to the center electrode is kept constant at the minimum safe distance (2CM), the distance d2 from the fingers to the peripheral electrodes varies from 0 degree to 90 degrees depending on the perpendicular angle of the fingers to the hover button, from the minimum d2 ═ d1+ Δ d to the maximum d2 ═ d1+ finger length. Fig. 2-4 represent the case where a large area of a human body is close to the hover button, and since the palm can completely cover the hover button, the projected area from the palm to the central electrode is equal to the area S11 of the central electrode itself, the projected area from the palm to the peripheral electrode is equal to the area S21 of the peripheral electrode itself, and the distance d1 from the palm to the central electrode is also maintained at the minimum safe distance, where d2 is d1+ Δ d. The embodiment of the invention selects the radius r1 of the central electrode to be 1.25CM, the radius of the inner ring of the peripheral electrode to be 1.25CM, the radius r2 of the outer ring to be 1.75CM, the height difference delta d between the central electrode and the peripheral electrode of the convex electrode structure to be 0.5CM, and the following table shows the theoretical calculated values of C1/C2 when the fingers with the diameter of 1CM approach the hovering button from different angles and the palm approaches the hovering button:

as can be seen from the table, C1/C2 of the horizontal palm is 1.3, and C1/C2 of the fingers are 7 and 15 at various angles, which shows that the large-area body part represented by the palm is obviously different from the small-area fingers, and we can distinguish the approach of the fingers and the palm very reliably by selecting the threshold value of C1/C2 to be 3 x 1.30 to 3.9 according to 3 times of redundancy, and a large amount of experimental data performed by our company laboratories prove the above conclusion.

Time-sharing measurement

As shown in FIG. 6, the present invention uses the analog switch in the CDC circuit of the capacitance-to-digital conversion circuit to periodically detect the self-capacitance C1 formed by the central electrode 1-1 and the human body, the self-capacitance C2 formed by the peripheral electrode 1-2 and the human body, and the mutual capacitance C3 formed by the central electrode 1-1 and the peripheral electrode 1-2, and divides a measurement period T into 3 time segments T1, T2 and T3. As shown in FIG. 6, during time T1, the analog switches 3-3 and 3-5 are closed, the analog switches 3-4 and 3-6 are opened, the square wave excitation signal is applied to the center electrode 1-1, and the capacitance measurement signal is also taken from the center electrode 1-1; in the period of T2, the analog switches 3-3 and 3-5 are opened, the analog switches 3-4 and 3-6 are closed, the square wave excitation signal is applied to the peripheral electrode 1-2, and the capacitance measurement signal is also taken out from the central electrode 1-2; and the time period T3, the analog switches 3-3 and 3-6 are closed, and the analog switches 3-4 and 3-5 are opened. At this point a square wave excitation signal is applied to the peripheral electrode 1-2 and a capacitance measurement signal is taken from the center electrode. By adopting the time-sharing measurement method, on one hand, the capacitance detection sensitivity can be improved to an ff pole to meet the requirement of the minimum safe distance, and on the other hand, the Patent No.: the holding of the equipotential of the center electrode and the peripheral electrode proposed in US7,498,822B 2 to eliminate the influence of C3, and in contrast, the use of C3 whose time-sharing measurement is not influenced by C1 and C2, can make the hover button retain the function of contact quick trigger.

Active hover trigger area

3-2, the present invention utilizes measurements of capacitance values of C1, C2, and C3 to computationally set the effective hover trigger region 2-9 of the hover button of the present invention, represented by the dashed cylinder above the center electrode 1-1, when a finger enters the region where the hover time exceeds a specified hover time threshold (e.g., 1 second), the hover button is triggered. The present embodiment sets the distance dmin from the bottom surface of the effective hover trigger region to the center electrode 1-1 to 0.5CM, and once the distance of the finger from the center electrode is less than 0.5CM, no hover time is required and the hover button can be triggered immediately. The distance dmax from the upper surface of the effective hovering trigger area to the central electrode is set to be 4CM, and the minimum safe distance dsaf from the finger to the hovering button is set to be 2CM, so that a vertical jitter interval of 2CM above the minimum safe distance can be ensured, the triggering reliability is improved, and the radius r of the effective hovering trigger area is approximately equal to the radius r1 of the central electrode. As shown in fig. 3-1. Under the condition of determining Δ d, the vertical distances dmax, dsaf and dmin are all in a monotonic function relation with the capacitance ratio C1/C2, and can be determined by calculating the value of C1/C2, the larger Δ d, the higher the vertical distance resolution, but the larger Δ d, the lower the sensitivity of the hovering button, so that generally between 0.1CM and 1CM should be selected, and through repeated experiments, it is found that a distance (height difference) between two electrodes of 1.0 MM to 8.9MM is more appropriate, which gives consideration to the sensitivity of measurement, electrode design and application to a wide range of users, and in this embodiment, Δ d is preferably 0.5 CM. The principle of setting and calculating the effective hovering triggering area is shown in fig. 2, 3-1 and 3-2, wherein Δ d is the height difference between the central electrode 1-1 and the peripheral electrode 1-2 of the convex structure, d1 is the distance from the central electrode to the finger, d2 is the distance from the peripheral electrode to the finger, S1 is the projected area of the finger on the central electrode, S2 is the projected area of the finger on the peripheral electrode, and the basic formula of capacitance can be used to obtain the calculation principle

C1/C2＝ε1*S1*d2/ε2*S2*d1＝ε1*S1*(d1+Δd)/ε2*S2*d1，---(1)

Where e 1 and e 2 are the dielectric constants of the capacitors C1 and C2, respectively, and e 1 is ═ e 2 under the same measurement environment, so that the formula (1) after the approximation becomes: C1/C2 ═ S1 (d1+ Δ d)/S2 d1- - - (2)

(2) The formula shows that C1/C2 is independent of dielectric constant. (2) After finishing the formula, the compound can be obtained:

D1＝Δd/((S2/S1)*(C1/C2)-1)---(3)

since the projected areas S1 and S2 of the finger are substantially unchanged when the finger changes from 0 to 90 degrees in the direction perpendicular to the central electrode 1-1, i.e., S2/S1 is constant, equation (3) indicates that the finger approach distance is in one-to-one inverse relationship with the ratio of the two capacitances C1/C2, i.e., the finger approach distance d1 can be calculated by C1/C2, so that the maximum height dmax, the minimum height dmin and the minimum safe distance dsaf of the effective hover trigger region 2-9 of the approximate cylinder as shown in fig. 3-2 can all be set by the corresponding ratio of C1/C2, and the radius r of the effective hover trigger region 2-9 can be defined to be approximately equal to the radius r1 of the central electrode 1-1 by the capacitance value of the mutual capacitance C3 between the central electrode 1-1 and the peripheral electrode 1-2. Note that the influence of the dielectric constant epsilon is not already present in equation (3), so that the influence of the temperature, humidity and different media of the measurement environment on the distance measurement accuracy is eliminated.

For the various center electrodes shown in fig. 11, the effective hovering triggering area at the upper part of the center electrode is a cylinder whose cross-sectional shape is the projection of the outer circumference of the center electrode, the bottom part is the distance dmin from the center electrode, and the upper part is the distance dmax from the center electrode, where dmin is 0.5CM and dmax is 4 CM. For dmin, it is mainly considered that mutual capacitance detection judgment is very accurate and is not influenced by environment too much, and setting the value is a consideration for judging whether a user wants to trigger quickly, and for dmax, the resolution and accuracy of measurement are effectively balanced, and the problem caused by necessary jitter of a finger of the user in the hovering triggering process is also balanced.

Time of hover

Under the application condition of a plurality of hovering buttons, when fingers search for effective hovering trigger areas of a target hovering button, false triggering of adjacent hovering buttons can be caused by the effective hovering trigger areas of the adjacently arranged hovering buttons, so that the false triggering of the adjacent hovering buttons is avoided; the invention adopts a method for prescribing the hovering time of the finger in the effective hovering triggering area of the hovering button so as to avoid the false triggering of the path button. According to different application scenes, the hovering time can be regulated to be between 0.3s and 5s, in principle, the longer the hovering time is, the better the false triggering prevention effect is, but the too long hovering time can prolong the triggering response time and influence the operation experience of a user, and the elevator hovering button of the embodiment of the invention regulates the hovering time to be 0.5s-1 s.

Fast triggering area

As mentioned above, the hover button needs to have a hover time (e.g. 0.5s-1s), in order to meet the diversified needs of people and the fast trigger requirement of the hover button in an emergency situation, the hover button needs to retain the function of contact fast trigger, i.e. the function of immediately triggering the button switch without waiting for the end of the hover time when the finger touches the surface of the hover button, see FIGS. 3-2, when the human finger is closer to the center electrode than the effective hover trigger area range, i.e. the distance between the finger and the center electrode is less than dmin, the human finger enters the fast trigger area 2-10, and at this time, the hover button will be immediately triggered without waiting for the end of the hover time.

Active shielding

Referring to the schematic diagram of a single electrode unit in fig. 4-1 and two adjacent electrode units in fig. 5, in order to suppress the interference and crosstalk between the adjacent electrode units or the environment to the central electrode 1-1 and the peripheral electrode 1-2, the crosstalk prevention electrode 1-4 is disposed, but the disposition of the crosstalk prevention electrode 1-4 may cause the problem of the decrease of the measurement sensitivity of the central electrode 1-1 and the peripheral electrode 1-2, and in order to increase the measurement sensitivity, the active shielding electrode 1-3 is disposed between the peripheral electrode 1-2 and the crosstalk prevention electrode 1-4, while the active shielding electrode 1-3 is a technology developed in the CDC, i.e., the CDC depends on the operational amplifier in the operational amplifier to form a voltage follower connected to the central electrode or the peripheral electrode, so that the central electrode 1-1 or the peripheral electrode 1-2 and the large-area metal ground or the ground electrode 1-4 The active shielding electrodes 1-3 between the two electrodes are kept at the same electric potential, so that the loss of the electric field energy of the measuring electrode to the ground bypass is avoided or reduced, the measuring sensitivity of the capacitors C1 and C2 is improved, and the requirement of the minimum safety distance is met.

Further, in many scenarios of hover button applications, there is typically a large area of metal ground at the bottom of the hover button, for example, elevator car housings are typically constructed of metal, the car housing needs to be grounded for safety, for the self-capacitance C1, and C2 of the hover button, the large area of the grounding metal at the bottom can greatly reduce the measurement sensitivity of C1 and C2, so that the hovering button can not meet the requirement of the minimum safe distance, as shown in fig. 4-2, the present invention arranges another active shielding electrode 1-7 at the bottom of the convex structure peripheral electrode 1-2, in the embodiment of fig. 4-2, by virtue of the vias 1-8 of the PCB (communicating the active shield electrodes 1-3 with 1-7), experiments have shown that cross-talk between adjacent external electrodes and the effects of large area ground metal can be reduced to an acceptable level with the above-described structure.

Acousto-optic feedback

Touch buttons typically provide tactile feedback to the operator in two states, a triggered state and a non-triggered state, through the displacement action of a mechanical switch or an audible and visual feedback circuit, so that the operator can confirm that the button switch has been successfully triggered and can let the hand leave the button. Referring to fig. 8, 9 and 10, the hover button of the present invention also includes an acousto-optic feedback control circuit 5-3 and a multi-color LED indicator 5-4, unlike the above-mentioned tactile feedback of two states of the touch button, in order to avoid no trigger caused by the finger passing through the effective hover trigger region, the finger needs to hover in the effective hover trigger region for a specified time, and the hover button needs non-contact tactile feedback (realized by light or sound) of at least 3 states. The first state is a no-trigger state, indicating that the finger has not entered the active hover trigger region, which may be lighted off or indicated silently; the second state is a pre-trigger state indicating that the finger has entered a valid trigger range, which may be indicated by a single color light flashing or illuminating a particular color (e.g., yellow) of a multi-color light, or by some alert tone alerting the operator that the active hover trigger zone of the hover button has been entered, and the third state is a trigger state indicating that the finger has hovered within the active trigger zone for a specified hover time, the hover button has been actuated, which may be indicated by a single color light flashing to a normally lit or multi-color light changing to another color, or by another alert tone.

Description of the schematic block diagrams

Referring to fig. 9, the central electrode 1-1, the peripheral electrode 1-2 and the active shielding electrodes 1-3 and 1-7 are all connected to the CDC, the CDC periodically measures the self-capacitance C1 formed between the central electrode 1-1 and the human body, the self-capacitance C2 formed between the peripheral electrode and the human body, and the mutual capacitance C3 formed between the central electrode 1-1 and the peripheral electrode 1-2 in a time-sharing manner, and in order to improve the sensitivity of C1 or C2, an operational amplifier in the CDC is used to form a voltage follower, so that the electrodes 1-3 and 1-7 and 1-2 form an equipotential to achieve the effect of active shielding (see fig. 4-2 and 4-3 again). The CDC inputs the measured capacitance values of C1, C2 and C3 to the MCU, the MCU calculates the value of C1/C2, judges whether the finger enters or leaves the effective hovering trigger area 2-9 through calculation according to the values of C1/C2 and C3, provides three-state acousto-optic feedback through an acousto-optic feedback control circuit according to the judgment result, and simultaneously sends a trigger logic signal of the hovering button to the elevator central controller through a communication circuit.

Electrode arrangement

In order to meet the requirement that the fingers are parallel to the hovering button to trigger the switch in different directions, the central electrode is preferably circular, the outer electrode is preferably annular, and a polygon can be adopted, the central electrode can be arranged by a plurality of electrodes, the reliability of a quick triggering area is further improved by utilizing mutual capacitance among the electrodes, and the peripheral electrode can also be arranged by a plurality of electrodes, so that the radius of the triggering area approximate to a cylinder can be determined more accurately. Fig. 11-1, 11-2, 11-3, 11-4, 11-5, 11-6 show the layout of 2 pieces of central electrode, 3 pieces of central electrode, 6 pieces of peripheral electrode of central electrode, 2 pieces of peripheral electrode of central electrode, 1 piece of non-closed loop of peripheral electrode of 3 pieces of central electrode, two pieces of non-closed loop of peripheral electrode of central electrode, and 1 piece of non-closed loop of peripheral electrode of central electrode, respectively. That is, the central electrode may be formed by multi-lobes, and the peripheral electrode may be formed by a closed loop or an open loop, or by a semicircular ring. Furthermore, the anti-crosstalk grounded ring electrodes 1-4 and the active shield electrodes 1-3 may also be arranged at the same level as the central electrode as shown in fig. 4-3.

Method of operation

The hovering button operation method of the present invention is shown in fig. 12, when the hovering button is powered on and started, a no-trigger logic signal is output first, and then a no-trigger periodic cycle detection and calculation stage is entered, in which whether the finger enters an effective hovering trigger area is judged, if not, the acousto-optic feedback control circuit outputs a no-trigger state, and continues to perform detection and calculation in a cycle manner, until the finger enters the effective hovering trigger area after detection and calculation is performed, the acousto-optic feedback control circuit outputs a pre-trigger state, and the hovering timer starts timing, and enters a pre-trigger cycle detection and calculation stage. In the pre-trigger cycle detection and calculation stage, if the finger leaves the effective hovering trigger area, the hovering timer is reset, the acousto-optic feedback control circuit outputs a non-trigger state, and the non-trigger cycle detection and calculation stage is returned; if the finger further enters the fast trigger area or the hover timer exceeds the preset hover time, the acousto-optic feedback control circuit outputs the trigger state, simultaneously outputs a logic trigger signal, and enters a cycle detection and calculation stage after triggering. In the cycle detection and calculation stage after triggering, if the finger leaves the effective hovering triggering area, outputting a non-triggering state signal, resetting the hovering counter, simultaneously performing acousto-optic feedback on the non-triggering state, and returning to the non-triggering cycle detection and calculation stage. The hovering button operation method of the invention can meet the requirements of the following three operation modes: the first is a single-trigger mode, i.e. after triggering, the finger can leave the effective hovering trigger area immediately and does not need to be triggered again (suitable for elevators, various door switches, toilet flushing switches, etc.); the second is a continuous trigger mode, namely, after being triggered, the finger can leave the effective hovering trigger area immediately, and meanwhile, a trigger logic signal is continuously output, and a non-trigger signal (suitable for controlling a tap switch of a bath or a hand basin and various lighting lamp switch lamps) is not output until the finger triggers the hovering switch for the second time; and thirdly, a hover keeping triggering mode is adopted, namely after triggering, the finger is kept in the effective hover triggering area, the triggering logic signal is continuously output in the period, and the no-triggering logic signal is not output until the finger leaves the effective hover triggering area (the no-triggering logic signal is suitable for public drinking water control buttons in offices, high-speed rails, airports, stations and other places). In view of the problems that the capacitive sensor is easily interfered and the measurement sensitivity of the human finger is limited by the environmental conditions of the use occasion, the purpose created by the invention is realized by fully utilizing the technology of the CDC of the existing mature capacitive-to-digital conversion circuit and matching with the design of the capacitive sensor.

Examples

For the case where the elevator buttons are one, i.e. the call buttons of the lowest floor and the highest floor, fig. 7 shows the most reasonable embodiment, which can also be conveniently applied to other similar fields, such as the design of the trigger button of a water faucet; for the two button (double button basic control unit) solution of the elevator up and down switch design, fig. 8 gives an example of a reasonable arrangement; for more floor buttons in the elevator car, the interface capability of each CDC chip, the reliability and the precision of measurement guaranteed in circuit board design and the consideration of economy are considered, the optimal design is that a row of buttons are integrated together, and the buttons of each row are connected together like building blocks through serial interfaces and then connected with a master controller. The following three embodiments are described separately:

first embodiment

One embodiment of the hovering button of the invention is an independent hovering button, and as shown in a structure diagram of the independent hovering button and a schematic circuit diagram of the independent hovering button in fig. 7, the independent hovering button is manufactured by adopting a multilayer circuit board 1-6, a central electrode 1-1 is manufactured on the top layer of the circuit board, a peripheral electrode 1-2 is manufactured on the second layer of the circuit board, an active shielding electrode 1-7 is manufactured on the third layer of the circuit board, and a power circuit 5-1, a communication circuit 5-2, a CDC circuit 3 and an acousto-optic feedback control circuit 5-3 are arranged on the 4 th layer of the circuit board. The first layer of the circuit board is provided with an LED light-emitting element 5-4, the panel 4-1 is made of acrylic or transparent PC, the top layer is in a shape of a key printed by adopting luminous ink silk screen printing, and other positions of the top layer are in a shape of opaque ink silk screen printing to ensure that the button state can be displayed when the LED light-emitting element 5-4 is lightened. The back of the panel 4-1 is connected with the top layer of the multi-layer circuit board of the key by adopting a bonding mode, and the metal shell 4-7 can be connected with the multi-layer circuit board and the panel by adopting a bonding mode. As shown in the equivalent circuit diagram of fig. 9, there is a CDC dedicated chip 3 integrating CDC and MCU on the bottom layer of the multilayer circuit board 1-6 for measuring capacitance values C1, C2 and C3 of the hover button and realizing the function of the hover button by calculating the ratio of C1/C2 and comparing the size of C3. The top layer of the multilayer circuit board 1-6 is also provided with a multicolor LED light-emitting element 5-4 and an acousto-optic feedback control circuit 5-3 on the bottom layer of the multilayer circuit board, which are used for realizing the tri-state light feedback (namely, a bright green lamp when a finger does not enter an effective hovering triggering space, a bright purple lamp when the finger enters the effective hovering triggering space, and a bright red lamp when a hovering button is triggered), the top layer of the multilayer circuit board is provided with a central electrode 1-1, the second layer is provided with a peripheral electrode 1-2, and the third layer is provided with an active shielding electrode 1-7, so that the problem that the sensitivity is reduced by a metal casing ground 4-7 and a bottom layer control circuit layer is avoided at the same time. And a power circuit 5-1, a CDC circuit 3 and a communication circuit 5-2 are arranged on the 4 th layer of the circuit board, and are communicated with a control and signal system of the elevator through a serial communication interface, so that the functions of calling control and light indication of the elevator are realized. The hovering independent button with the convex structure has a simple structure and low cost, and can be conveniently used for replacing the existing mechanical contact type independent button switch.

Second embodiment

Another embodiment of the hovering button of the invention is a double-hovering button for elevator hall call, as shown in a structure diagram 8 and a schematic diagram 9, a central electrode 1-1 of two hovering buttons is silk-screened on a transparent panel 4-1 by silver paste, a light-homogenizing plate 4-2 for making light feedback light uniform is arranged under the transparent panel 4-1, the transparent panel and the light-homogenizing plate are fixed with a peripheral electrode PCB 4-4 through a frame 4-3, and the vertical distance difference delta d between the central electrode and the peripheral electrode of the convex electrode structure is controlled to be 0.5CM through the frame, a control PCB board 4-6 is provided below the electrode PCB board 4-4, as shown in the equivalent circuit diagram of fig. 9, a CDC special chip integrating CDC and MCU is arranged on the control PCB 4-6, the method is used for measuring the capacitance values C1, C2 and C3 of the hover button, and realizing the function of the hover button by calculating the ratio of C1/C2 and comparing the size of C3. The control PCB 4-6 is also provided with a multicolor LED indicator lamp 5-4 and an acousto-optic feedback control circuit 5-3 for realizing the three-state light feedback (namely, a bright green lamp when a finger does not enter an effective hovering triggering space, a bright purple lamp when the finger enters the effective hovering triggering space, and a bright red lamp when a hovering button is triggered), the upper layer of the PCB 4-4 is provided with a peripheral electrode 1-2, an annular active shielding electrode 1-3 and an annular grounding electrode 1-4, the lower layer of the PCB 4-4 is provided with an active shielding electrode 1-7, and the active shielding electrode is connected with the annular active shielding electrode on the electrode PCB 4-4 through a PCB through hole 1-8, so as to avoid the problem that the sensitivity is reduced by a metal shell ground and an external annular grounding electrode. The control PCB 4-6 is also provided with a power circuit 5-1, a CDC circuit 3 and a communication feedback circuit 5-2, and the control and signal system of the elevator is communicated with the control and signal system of the elevator through a serial communication interface, so that the functions of outbound control and light indication of the elevator are realized.

Third embodiment

Another embodiment of the hover button of the present invention is a multi-row hover button for floor selection control in an elevator car, where multiple dual-button primary control units 4 and a centralized controller 6 are arranged on a metal frame in series via 6-1 individual unit communication lines and connected to the centralized controller 6, as shown in the block diagram 10 and the schematic diagram 9. Referring to fig. 8, the central electrodes 1-1 of two hovering buttons are printed on a transparent panel 4-1 by silver paste silk screen, a light homogenizing plate 4-2 for making light feedback light uniform is arranged below the transparent panel 4-1, the transparent panel and the light homogenizing plate are fixed with an electrode PCB 4-4 through a frame 4-3, and the vertical distance difference delta d between the central electrode and the peripheral electrode of the convex electrode structure is controlled to be 0.5CM through the frame, a control PCB board 4-6 is provided below the electrode PCB board 4-4, as shown in the equivalent circuit diagram of fig. 9, a CDC special chip integrating CDC and MCU is arranged on the control PCB 4-6, the method is used for measuring the capacitance values C1, C2 and C3 of the hover button, and realizing the function of the hover button by calculating the ratio of C1/C2 and comparing the size of C3. The control PCB 4-6 is also provided with a multicolor LED indicator lamp 5-4 and an acousto-optic feedback control circuit 5-3 for realizing the three-state light feedback (namely, a bright green lamp when a finger does not enter an effective hovering triggering space, a bright purple lamp when the finger enters the effective hovering triggering space, and a bright red lamp when a hovering button is triggered), the upper layer of the PCB 4-4 is provided with a peripheral electrode 1-2, an annular active shielding electrode 1-3 and an annular grounding electrode 1-4, the lower layer of the PCB 4-4 is provided with an active shielding electrode 1-7, and the active shielding electrode is connected with the annular active shielding electrode on the electrode PCB 4-4 through a PCB through hole 1-8, so as to avoid the problem that the sensitivity is reduced by a metal shell ground and an external annular grounding electrode at the same time. The control PCB 4-6 is also provided with a power supply circuit 5-1, a CDC circuit 3 and a communication feedback circuit 5-2, the control PCB 4-6 is connected to the centralized control PCB 6 through an internal serial communication cable 6-1, an MCU (reference number 6-3) is arranged on the centralized control 6 and is responsible for comprehensively analyzing the key actions of the basic unit 4 so as to further reduce misoperation, the centralized power supply module 6-2 is responsible for supplying power to the power supply circuit 5-1 of the independent control unit 4, and the centralized communication control module 6-4 is responsible for communicating with the elevator central controller and simultaneously communicating with each basic control unit 4, so that the floor control and light indication functions of the elevator are realized.

The final effect is as follows:

compared with the technical scheme disclosed in the U.S. Pat. No. 7,498,822B 2, in order to avoid the capacitance effect between the central electrode and the external electrode from affecting the measurement of the self-capacitance between the central electrode and the external electrode and the self-capacitance between the human body or the conductive object, it is required that equal voltage signals must be applied to the central electrode and the external electrode at the same time during the capacitance measurement to form an equipotential between the two electrodes, this design increases the complexity of the measurement circuit to cause cost increase on one hand, and cannot utilize the correction effect of the mutual capacitance parameter formed between; the capacitance digital conversion circuit adopted by the invention, such as a CDC chip based on delta-sigma principle, can periodically and respectively measure the self-capacitances C1 and C2 of the two electrodes and the mutual capacitance C3 value between the two electrodes in a time-sharing manner, the three capacitance measurements are not mutually influenced, and accurate capacitance values of C1, C2 and C3 can be obtained without the limitation of equipotential between the two electrodes. The technical problem to be solved by the hovering button is to avoid the influence of the environmental temperature and humidity change on capacitance measurement; the invention adopts the ratio of the central capacitance to the external capacitance as the main judgment basis, and the capacitance ratio is irrelevant to the dielectric constant mainly influenced by temperature and humidity.

The hovering button can effectively prevent false triggering caused by large-area approaching of a human body to the hovering button, for example, when people in an elevator are many, the arm or the back of the elevator is close to or clings to the hovering button, and when cleaning, the palm or the fist of the elevator is clung to the hovering button. Under the pointing action of fully utilizing the palm of a human body to stretch out one finger, the general length of the finger is obviously different from the action of the whole palm on the two electrodes designed by the invention, so that the length of the index finger of adults is about 6-8CM and the length of the index finger of children is 4-6CM in consideration of the fact that most people are used to operate a button switch by using the index finger, and the diameter (circular) or the side length (square) of the external electrode is controlled within 4CM in order to avoid the increase of the projection area of the index finger on the external electrode by the rest 4 fingers.

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 hover button sensor unit, comprising: the device comprises a power circuit, a capacitance sensor, a capacitance digital conversion circuit, a control module, an acousto-optic feedback control circuit and a communication circuit;

2. The hover button sensor unit of claim 1, wherein the control module is coupled to an acousto-optic feedback control circuit that exhibits three states, no-trigger, pre-trigger and trigger.

3. The hover button sensor unit of claim 1, wherein an active shielding electrode is behind the peripheral electrode.

4. The hover button sensor unit of claim 1, wherein the outer peripheral electrode has an annular active shielding electrode on the outside.

5. The hover button sensor unit of claim 3 or 4, wherein the active shield electrode is connected to the center electrode and the peripheral electrode via operational amplifiers forming voltage followers.

6. The hover button sensor unit of claim 4, wherein the annular active shield electrode is surrounded by a surrounding anti-crosstalk electrode.

7. The hover button sensor unit of claim 1, wherein the active hover trigger region at the top of the center electrode is a cylinder with a cross-sectional shape that is a projection of the outer perimeter of the center electrode, the bottom being a distance dmin from the center electrode, and the top being a distance dmax from the center electrode, where dmin is 0.5CM and dmax is 4 CM.

8. The hover button sensor unit of claim 1, where the center electrode is comprised of multiple lobes.

9. The hover button sensor unit of claim 1, where the peripheral electrode is a closed loop or an open loop, circular ring, or is comprised of a semi-circular ring.

10. A method for providing a hover button trigger, characterized in that, based on the sensor unit as defined in claims 1-9, the entering of a human finger into an effective hover trigger region above a certain central electrode is detected and calculated by a capacitive sensor, and a pre-trigger response of the entering of the human finger into the effective hover trigger region is provided by an acousto-optic feedback control circuit;

11. The method of claim 10, wherein the hover time is between 0.3 and 5 seconds, and the optimal hover time is 0.5-1 second.

12. The method of claim 10, wherein the active hover trigger region of the top portion of the center electrode is a cylinder with a cross-sectional shape of the projection of the outer perimeter of the center electrode, a bottom portion of the cylinder being a distance dmin from the center electrode, and a top portion of the cylinder being a distance dmax from the center electrode, wherein dmin is 0.5CM and dmax is 4 CM.

13. The method as claimed in claim 10, wherein the control module is connected to an acousto-optic feedback control circuit, and the acousto-optic feedback control circuit exhibits three states of no-trigger, pre-trigger and trigger.