CN105260728A - Uniform sensing structure of fingerprint reading surface of fingerprint reader - Google Patents
Uniform sensing structure of fingerprint reading surface of fingerprint reader Download PDFInfo
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- CN105260728A CN105260728A CN201510778242.8A CN201510778242A CN105260728A CN 105260728 A CN105260728 A CN 105260728A CN 201510778242 A CN201510778242 A CN 201510778242A CN 105260728 A CN105260728 A CN 105260728A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1324—Sensors therefor by using geometrical optics, e.g. using prisms
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Abstract
The invention discloses the uniform sensing structure of the fingerprint reading surface of a fingerprint reader. The structure comprises an induction chip, a prism and a housing. The fingerprint reading surface of the prism forms an included angle relative to the induction chip. The induction chip is provided with a notch or is hollowed-out along the included angle direction of the fingerprint reading surface. According to the technical scheme of the invention, based on the chip induction principle of the induction chip, the capacitive finger sensing chip acquires the capacitance variation value between a sensing finger and the induction chip so as to realize the finger sensing function. At the same time, the capacitance value of a capacitive element is related to the structure of the capacitive element. In this way, the sensing finger can be uniformly distributed through easily designing the board-to-board directly facing area S based on three easily designed parameters that affect the capacitance value result of a capacitance value formula (2) of the capacitive element. Meanwhile, an appropriate k value is calculated based on a deformed equation (8). Therefore, the required compensation design for the capacitance variation value and the board-to-board dielectric coefficient epsilon of the sensing finger in environments of different requirements can be realized. The finger sensing capacity is uniformly distributed to the hilt.
Description
Technical field
The invention belongs to induction structure, more particularly, relate to a kind of fingerprint capturer and adopt finger face uniform induction structure.
Background technology
In recent years fingerprint identification technology development, its use also slowly spreads to daily life.Because the light channel structure of optical fingerprint head limits, traditional optical fingerprint head adopts finger face finger induction sensitivity skewness, causes induction trigger pip ability inconsistent.The use inconvenience thereupon brought is mainly reflected in following several respects: a) because sense refers to that sensitivity profile is uneven, adopt on the surface level of finger face and identify finger presses ability domain of the existence, cause finger presses to adopt finger face and adopt and refer to signal to be sent to control chip susceptibility inconsistent.B) touch effect time finger presses adopts finger face to differ, cause user's experience, comfort level influenced.C) because sensing chip design is insuperior, fingerprint module induction sensitivity and lockset adaptation bother, difficulty, when inductance capacitance coupling is bad, touches lockset shell and also will trigger fingerprint module work.
Square can making by conductive metal sheet commonly used by sensing chip material, is connected by metal sensing chip with wire with corresponding process chip pin.Identify finger touching principle mainly according to finger with electrostatic, when pointing near sensing chip, the finger face of static electrification and sensing chip form one and align electrode, sensing chip is assembled and points electrically contrary electric charge, now the finger face of static electrification and sensing chip form an interim capacity cell.Capacitive element electric capacity be defined as between two pole plates for unit voltage time, the quantity of electric charge that each pole plate holds:
In formula, capacitance C size is only by the structures shape of capacitor element, and algorithm is:
In formula, S is the dielectric coefficient that between parallel-plate, right opposite amasss, d is parallel-plate spacing, ε is insulating medium between parallel-plate.From (1) formula, when S is fixed value, between plate, voltage and electric capacity C are inversely proportional to, and static electrification finger is when sensing chip, and on sensing chip, electric charge is constantly assembled, if the ratio of varying capacitance is set to K between plate, so has as shown in the formula son:
ΔC＝C
a-C
b··········(3)
When K reaches certain value, process chip has detected that finger is close, and chip can according to requiring that exporting height electric signal applies for fingerprint Development of Module.
Capacity cell capacitance formula is known, and capacitance C is not fixed value, and itself and right opposite amass insulating medium ε between S, plate and be directly proportional, and are inversely proportional to from d with distance between plates.Finger face is adopted for ease of timely finger sensing pressing, conventional optical fingerprint module sensing chip need be installed on to be adopted below the prism of finger face, and sensing chip is rectangular metal sheet, so when point adopt any region, finger face with equal area pressing time, namely in (2) formula, S and ε is definite value.The interim capacitive element C that such finger and sensing chip produce and finger identity distance sensing chip distance d inversely, namely adopt refer to identity distance from sensing chip distance more close to point and interim capacitive element C value between sensing chip larger, as shown in Figure 1.
Equal area is so just caused to point the induction sensitivity meeting difference in each region when finger face is adopted in touch, nearest one end, finger face is adopted in sensing chip distance, even also may not touch at finger and adopt finger face and understand flip chip equally and recognized finger touch, cause false triggering.
Technology today, for reducing induction sensitivity, prevents the scheme of false triggering from being be a sensing chip basic electric capacity C in parallel
bthe ratio of varying capacitance K value that capacitance change is caused reduces thus reduces the sensitivity of sensing chip entirety, for solving the false touch problem of the sensitiveest end, but often cause holding near d2 the Trigger Function that loses induction in Fig. 1, this method thoroughly cannot solve to adopt and refer to area sensitivity problem pockety.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, provide a kind of sensitivity profile even, the fingerprint capturer that matching effect is good adopts finger face uniform induction structure.
This fingerprint capturer adopts finger face uniform induction structure, comprises sensing chip, prism and shell, described prism adopt finger face and sensing chip forms angle; Described sensing chip along with adopt finger face and form angle direction and be provided with breach or hollow out.
As preferably: the breach of described sensing chip is trapezoidal, serrate or S shape.
As preferably: the hollow out of described sensing chip is triangle, ellipse or circular.
As preferably: the right opposite adopting finger face of sensing chip and prism amasss S and meets functional relation:
S＝k·tanα·L
α is the angle angle of adopting finger face and sensing chip of described prism, L be on described sensing chip any point to the distance of adopting intersection, finger face of sensing chip and prism; Wherein
Δ C is the variable quantity that induction triggers required capacitance, and Δ C is fixed value, and ε is the dielectric coefficient of insulating medium between parallel-plate.
The invention has the beneficial effects as follows:
1. sense refers to that ability is even
Sensing chip is pointed by the capacitance change between collection finger and sensing chip to reach the ability felt and referring to by the known condenser type of induction chip principle of induction, simultaneously because the capacitance of capacity cell is relevant to component structure, the present invention is based in capacity cell capacitance formula (2) right opposite between the plate that affect in three parameters of capacitance and be easy to design and amass S, carry out sense and refer to the formula that is uniformly distributed design.By distortion formula (8), by calculating suitable k value, felt under varying environment being referred between capacitance change and plate, dielectric medium coefficient ε compensates design, sense to greatest extent can be reached and refer to that ability is uniformly distributed.
2. induction sensitivity coupling flexibly
Traditional optical finger print module sensing chip is when tackling different lockset shell, for preventing false triggering, often need according to the Cb value in different mould amendment formula (3), namely can not false triggering to expect to reach, can ensure again induction sensitivity enough trigger point close.But because sensitivity profile is uneven, often matching capacitance Cb is difficult to reach lockset designing requirement.The present invention by the mode that amendment sensing chip and finger right opposite amass S, sense is referred to ability is uniformly distributed in adopts finger face simultaneously, reduce the burst capability at the sensitiveest place originally, greatly can reduce the situation that sense refers to false triggering like this.Also can calculate the scale-up factor k value under same environment by formula (4) and formula (7) when sensing chip designs, to reach maximum coupling simultaneously.
Accompanying drawing explanation
Fig. 1 is that finger face capacity effect figure is adopted in touch;
Fig. 2 is breach scenario-frame schematic diagram of the present invention;
Fig. 3 is hollow out scenario-frame schematic diagram of the present invention;
Fig. 4 is the present embodiment structural representation;
Fig. 5 is the present embodiment sensing chip structural representation;
Description of reference numerals: sensing chip 1, prism 2, shell 3.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described further.Although the present invention will be described in conjunction with preferred embodiment, should know, and not represent and limit the invention in described embodiment.On the contrary, the present invention will contain can be included in attached claims limit scope of the present invention in alternative, modified and equivalent.
As shown in Figures 2 to 5, this fingerprint capturer adopts finger face uniform induction structure, comprises sensing chip 1, prism 2 and shell 3, described prism 2 adopt finger face and sensing chip 1 forms angle; Described sensing chip 1 along with adopt finger face and form angle direction and be provided with breach or hollow out.Adopting finger face is flat mirror, and due to finger and sensing chip, to touch area uncontrollable, therefore by the polar plate area on amendment sensing chip to reach the object controlling right opposite and amass, is obtained by formula (2) deformable:
Making C equal to respond to the capacitance variation amount needed for triggering is certain value, and so S and d is proportional, and above formula can be abbreviated as:
S＝k·d···········(8)
Can being drawn by above formula, diminishing when adopting finger face the closer to d value during sensing chip, for ensureing that C value is for triggering induced electricity capacity, so sensing chip amasss S with the right opposite in finger face and just should reduce little, S and d is linear.Simultaneously by light path and the structural drawing (4) of optical finger print module, easily know that d and L exists following funtcional relationship:
d＝tanα·L
(8) formula can transform by we:
S＝k·tanα·L···········(9)
Can by designing the profile of sensing chip for this characteristic, when making finger presses adopt any region, finger face, its right opposite amasss S becomes (9) formula funtcional relationship with distance d, can design two class sensing chip arrangements thus.Two schemes is as follows:
Sensing chip configuration design: cut sensing chip according to above-mentioned formula, is used for reducing diverse location right opposite is amassed by special formed, thus makes to adopt finger face and obtain uniform sense and refer to ability.Sample as shown in Figure 2:
Sensing chip inside is emptied: empty sensing chip according to above-mentioned formula, and the right opposite being used for reducing diverse location by different hole shape and hole size amasss, thus makes to adopt finger face and obtain uniform sense and refer to ability.Sample as shown in Figure 3:
The present invention is for an optical finger print module, and as shown in Figure 4, inclination angle, finger face adopted by prism is α=45 °, i.e. L=d.Prism material is glass material relative dielectric constant mean value is 4.The induction chip used triggers sense and refers to that sensing chip capacitance change needed for signal is for △ C=4pF, and sensing chip is of a size of 12.5mm*10mm.
Can not determining because finger touches area when finger face is adopted in touch, for reaching good uniform induction effect, sensing chip being divided into 20 deciles.Each little decile frame size is 2.5*2.5mm as shown in Figure 4, is inclined-plane owing to adopting finger face, the interim capacity cell that finger and sensing chip are formed, and its distance between plates is from the mean value (i.e. 1/2*d) getting little rectangular area and dip plane distance on row.According to distance by little rectangular area according to d value sequence number label, can be calculated by formula (7) and (9): S=1*d, following table:
| Sequence number | Distance between plates d value (mm) | Right opposite amasss S value |
| d1 | 1.25 | 1.25 |
| d2 | 2.50 | 2.50 |
| d3 | 3.75 | 3.75 |
| d4 | 5.00 | 5.00 |
| d5 | 6.25 | 6.25 |
Table 1 invention application example
After ensureing finger presses according to the little rectangular area domestic demand that the known distance d of table 1 is nearest, effectively right opposite amasss as 1.25mm2, easily calculate little rectangular area Sd=2.5*2.5=6.25, so carried out emptying process by the rectangle of its decile, each to empty little side hole area be 1.25mm.As shown in Figure 5: final acquisition sense refers to the comparatively uniform sensing chip of ability.
Traditional solution is by basic electric capacity C in amendment formula (4)
bchange ratio of varying capacitance K, this scheme cannot solve at all adopts finger face induction sensitivity problem pockety, and the design presses the special construction of optical finger print module for this reason, adopts a kind ofly to make to adopt the sense of finger face and refer to the New Scheme that ability is evenly distributed.For making sensing chip refer to that ability is identical adopting any region sense on finger face, induced electricity capacitance that any region, finger face produces is the same to make finger touch adopt.From capacitance values formula, static electrification finger amasss insulating medium ε between S, plate to the electric capacity that sensing chip produces to its right opposite and is directly proportional, and is inversely proportional to from d with distance between plates.
Optical finger print module when designing to the refractive index of prism material and adopt and refer to that plane inclination has corresponding requirements, therefore when sensing chip be positioned over adopt below finger face time, its with adopt finger face each region insulation dielectric medium coefficient ε and the d that just adjusting the distance and all cannot revise, therefore this programme be conceived to affect capacity cell capacitance another factor two-plate between right opposite amass S.Amass S by suitably revising finger with the right opposite of sensing chip, to realize finger touch, to adopt the inductance capacitance that finger face zones of different produces consistent, thus order is adopted the sense of finger face and referred to that ability is evenly distributed.
Claims (4)
1. a fingerprint capturer adopts finger face uniform induction structure, comprise sensing chip (1), prism (2) and shell (3), it is characterized in that: finger face of adopting and the sensing chip (1) of described prism (2) form angle; Described sensing chip (1) along with adopt finger face and form angle direction and be provided with breach or hollow out.
2. fingerprint capturer according to claim 1 adopts finger face uniform induction structure, it is characterized in that: the breach of described sensing chip (1) is trapezoidal, serrate or S shape.
3. fingerprint capturer according to claim 1 adopts finger face uniform induction structure, it is characterized in that: the hollow out of described sensing chip (1) is triangle, ellipse or circular.
4. fingerprint capturer according to claim 1 adopts finger face uniform induction structure, it is characterized in that: sensing chip (1) amasss S with the right opposite adopting finger face of prism (2) and meets functional relation:
S＝k·tanα·L
α is the finger face of adopting of described prism (2) and the angle angle of sensing chip (1), and L is the upper any point of described sensing chip (1) to the distance of adopting intersection, finger face of sensing chip (1) and prism (2); Wherein
Δ C is the variable quantity that induction triggers required capacitance, and Δ C is fixed value, and ε is the dielectric coefficient of insulating medium between parallel-plate.
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| CN201510778242.8A CN105260728B (en) | 2015-11-13 | 2015-11-13 | A kind of fingerprint capturer adopts finger face uniform induction structure |
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| CN201510778242.8A CN105260728B (en) | 2015-11-13 | 2015-11-13 | A kind of fingerprint capturer adopts finger face uniform induction structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110598656A (en) * | 2019-09-18 | 2019-12-20 | Oppo广东移动通信有限公司 | Fingerprint module, display screen assembly and electronic equipment |
Citations (6)
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| CN201438309U (en) * | 2009-06-23 | 2010-04-14 | 深圳市中控生物识别技术有限公司 | Fingerprint verification equipment with sensing and fingerprint-acquiring functions |
| CN101706869A (en) * | 2009-11-06 | 2010-05-12 | 浙江三安实业有限公司 | Living fingerprint capturer |
| CN201465142U (en) * | 2009-06-11 | 2010-05-12 | 成都方程式电子有限公司 | Induction type optical fingerprint collecting device |
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| CN201465142U (en) * | 2009-06-11 | 2010-05-12 | 成都方程式电子有限公司 | Induction type optical fingerprint collecting device |
| CN201438309U (en) * | 2009-06-23 | 2010-04-14 | 深圳市中控生物识别技术有限公司 | Fingerprint verification equipment with sensing and fingerprint-acquiring functions |
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| Title |
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| MENG-LIEH SHEU ET AL.: ""A Novel Capacitive Sensing Scheme for Fingerprint Acquisition"", 《2005 IEEE CONFERENCE ON ELECTRON DEVICES AND SOLID-STATE CIRCUITS》 * |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110598656A (en) * | 2019-09-18 | 2019-12-20 | Oppo广东移动通信有限公司 | Fingerprint module, display screen assembly and electronic equipment |
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