CN104034459A - Optical flexible two-dimensional tangential force touch sensor - Google Patents

Abstract

The invention discloses an optical flexible two-dimensional tangential force touch sensor, and belongs to the technical field of optical sensing. An optical biochemical sensor comprises a light source layer, a polymer flexible conducting layer and a photoelectric detection layer. Light emitted by a light source is irradiated on 2*2 array photoelectric detectors on the photoelectric detection layer, two-dimensional tangential force causes deformation and displacement of the polymer flexible conducting layer, the light currents of the 2*2 array photoelectric detectors are made to be changed, and the magnitude and direction of the two-dimensional tangential force can be acquired by calculating the relative change amount of the light currents. The optical flexible two-dimensional tangential force touch sensor enables the light source, the polymer flexible conducting layer and the photoelectric detection layer to be integrated together, and has the advantages of being small in size, high in flexibility, and capable of simultaneously detecting the magnitude and direction of the tangential force.

Description

The flexible two-dimentional tangential force touch sensor of optics

Technical field

The invention belongs to optical sensing field, be specifically related to the flexible two-dimentional tangential force touch sensor of a kind of optics.

Background technology

Touch sensor is that Intelligent bionic machinery people refers to that hand realization captures requisite assembly of elements to target object more, and especially the detection of tangential force is the reliable key capturing.Tradition electricity touch sensor, as resistor-type, capacitor type, magnetic conductance type etc., although can realize to a certain extent the obtaining of the real-time information such as pressure or tangential force of contact site, and adopt the flexible materials such as conductive rubber to realize the flexibility of sensor can docile function, but mostly there is the problems such as input and output wiring is complicated, manufacture craft difficulty is large, be particularly importantly subject in actual applications the environmental factors such as electromagnetic field and disturb.

Optics touch sensor in unique advantage aspect anti-electromagnetic interference (EMI), has potentiality realizing aspect anti-electromagnetic interference (EMI), softness haptic perception sensing function based on optical detection principle, and impressive progress is greatly paid close attention to and obtained in correlative study.

Formerly technology [1] (M.Ohka, N.Morisawa, H.Suzuki, J.Takata, H.Koboyashi, and H.B.Yussof. " A robotic finger equipped with an optical three-axis tactile sensor ", 2008IEEE International Conference on Robotics and Automation Pasadena, CA, USA, 2008, pp.3425-3430) in, utilize curved waveguide to be subject under extraneous power effect total reflection condition destroyed, part light wave leaks out from waveguide, reveal the measuring ability of light intensity distribution acquisition pressure and tangential force by detection.But this sensor be based on CCD detect light distribution, pick-up unit volume is large, complex structure, and sensor can not realize flexibility can docile function.

Formerly technology [2] (Zhi Feng Zhang, Xiao Ming Tao, Hua Peng Zhang, and Bo Zhu. " Soft fiber optic sensors for precision measurement of shear stress and pressure ", IEEE Sensors Journal, 2013, Vol.13, No.5, pp.1478-1482.) in, Plastic Fiber Gratings is imbedded in flexible polymer substrate according to level and vergence direction respectively, and in substrate outside, packing ring is installed, come detected pressures and tangential force by the wavelength shift of detection level fiber grating and inclined optical fiber grating.But the detection of this sensor realizable force needs expensive grating demodulation instrument, and cost is high.

Formerly technology [3] (Jeroen Missinne, Erwin Bosman, Bram Van Hoe, Geert Van Steenberge, Sandeep Kalathimekkad, Peter Van Daele, Member, and Jan Vanfleteren, " Flexible shear sensor based on embedded optoelectronic components ", IEEEPhotonics Technology Letters, 2011, Vol.23, No.12, pp.771-773) in, adopt flexible polymeric materials as conductive medium, under extraneous power effect, cause conductive medium deformation, obtain the size of tangential force by measuring the variation of photodetector received optical power.This sensor has been realized flexibility can docile function, and it is simple to detect demodulation method, but can only realize the detection of one dimension tangential force.

Summary of the invention

The present invention is directed to that the detection system volume that above-mentioned optics touch sensor exists is large, complex structure, cost is high, maybe can only realize the technical matterss such as one dimension shear force detection, proposes the flexible two-dimentional tangential force touch sensor of a kind of optics.

Technical scheme of the present invention is as follows:

The flexible two-dimentional tangential force touch sensor of a kind of optics, comprises conductive medium layer and photodetection layer that light source layer, flexible polymer form, the arrangement of joining successively from top to bottom.

Laser instrument is positioned at light source layer, and the matrix material of light source layer is flexible polymer.

The first photodetector, the second photodetector, the 3rd photodetector and the 4th photodetector are square, the length of side is a, is arranged in order counterclockwise and forms 2 × 2 photodetector arraies, and the length of side is 2a, be positioned at photodetection layer, the matrix material of photodetection layer is flexible polymer; The line at laser instrument center and 2 × 2 photodetector array centers is perpendicular to the plane of photodetection layer.

Described laser instrument is vertical cavity surface emitting laser, and on its light beam irradiates to 2 of sending × 2 photodetector array, hot spot is circular, and radius is R.

Described the first photodetector, the second photodetector, the 3rd photodetector and the 4th photodetector are slice-shaped photodetector, the width of encapsulation frame is d.

The flexible two-dimentional tangential force touch sensor of described optics, its sensing detection method has following steps:

A. when two-dimentional tangential force F puts on sensor unit, cause the deformation of polymer flexibility conductive medium layer horizontal direction, produce respectively the deformation Δ x of x direction and the deformation Δ y of y direction, the center of laser instrument and 2 × 2 photodetector array lines of centres are no longer perpendicular to the plane of photodetection layer, and on four photodetectors, receiving the photocurrent of exporting after the light wave of laser instrument is to be respectively I ₁, I ₂, I ₃and I ₄, ignore the impact of polymer flexibility conductive medium layer thickness variation on photodetector received optical power, there is (I ₂+ I ₃)-(I ₁+ I ₄) only relevant with the deformation Δ x of x direction, (I ₃+ I ₄)-(I ₁+ I ₂) only relevant with the deformation Δ y of y direction, meet following relation

$r_1\left(\mathrm{\Δx}\right)=\frac{(I_2+I_3)-(I_1+I_4)}{I_{\mathrm{to\; tal}}}---\left(1\right)$

$r_2\left(\mathrm{\Δy}\right)=\frac{(I_3+I_4)-(I_1+I_2)}{I_{\mathrm{to\; tal}}}---\left(2\right)$

Wherein I _total=I ₁+ I ₂+ I ₃+ I ₄be the photocurrent sum of four photodetector outputs, r ₁(Δ x) and r ₂(Δ is y) relative variation of photocurrent.

B. the component F of two-dimentional tangential force F in x direction and y direction _xand F _ymeet in the relation of the deformation Δ x of x direction and the deformation Δ y of y direction with polymer flexibility conductive medium layer

$F_x=\frac{\mathrm{\ΔxGS}}{D}---\left(3\right)$

$F_y=\frac{\mathrm{\ΔyGS}}{D}---\left(4\right)$

Wherein G is the tangential modulus of polymer flexibility conductive medium layer, and D is the thickness of polymer flexibility conductive medium layer, and S is lifting surface area.Big or small F and the direction θ of two dimension tangential force F are respectively

$F=\sqrt{F_x^2+F_y^2}---\left(5\right)$

C. measure the photocurrent relative variation r of four photodetector x directions and y direction ₁(Δ x) and r ₂(Δ y), according to formula (1) and (2), calculates deformation Δ x and the Δ y of x direction and y direction, utilizes formula (3), (4) and (5) to calculate the big or small F of two-dimentional tangential force; Utilize formula (6) to calculate the direction θ of two-dimentional tangential force.

Owing to having adopted technique scheme, the flexible two-dimentional tangential force touch sensor of optics provided by the invention has following outstanding beneficial effect:

(1) in the present invention, LASER Light Source, 2 × 2 photodetector arraies are all placed in flexible material layer, form two-dimentional tangential force touch sensor with polymkeric substance conductive medium layer, and simple in structure, cost is low, and there is flexibility can docile feature.

(2) the present invention, by detecting the photocurrent relative variation of four photodetectors, obtains tangential force size and Orientation information, and demodulation method is simple, can eliminate light source power and shake the impact on measurement result simultaneously.

Brief description of the drawings

The flexible two-dimentional tangential force touch sensor structural representation of Fig. 1 optics of the present invention.

Fig. 2 is not subject to extraneous power condition lower sensor vertical view.

Fig. 3 is subject to two-dimentional tangential force effect lower sensor vertical view.

Fig. 4 sensor x direction photocurrent relative variation r ₁relation curve with x direction deformation Δ x.

Fig. 5 sensor y direction photocurrent relative variation r ₂relation curve with y direction deformation Δ y.

In figure: 1 light source layer; 2 conductive medium layers; 3 photodetection layers;

11 laser instruments;

31 first photodetectors; 32 second photodetectors; 33 the 3rd photodetectors; 34 the 4th photodetectors.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

As shown in Figure 1, the flexible two-dimentional tangential force touch sensor of optics of the present invention comprises light source layer, polymer flexibility conductive medium layer and photodetection layer, the arrangement of joining successively from top to bottom; Laser instrument is positioned at light source layer, and light source layer medium is flexible polymeric materials; The first photodetector, the second photodetector, the 3rd photodetector and the 4th photodetector are square, the length of side is a, be arranged in order counterclockwise and form 2 × 2 photodetector arraies that the length of side is 2a, be positioned at photodetection layer, photodetection layer medium is flexible polymer; The line at laser instrument center and 2 × 2 photodetector array centers is perpendicular to the plane of photodetection layer.Laser instrument is vertical cavity surface emitting laser.

Fig. 2 is not subject to extraneous power condition lower sensor vertical view, and on light beam irradiates to 2 × 2 photodetector array that laser instrument sends, hot spot is circular, and radius is R.The first photodetector, the second photodetector, the 3rd photodetector and the 4th photodetector are slice-shaped photodetector, the width of encapsulation frame is d.The center superposition of the center of circle of laser instrument output facula and 2 × 2 photodetector arraies.

Fig. 3 is subject to two-dimentional tangential force effect lower sensor vertical view, two dimension tangential force F causes the deformation of polymer flexibility conductive medium layer horizontal direction while putting on sensor unit, the center of laser instrument and 2 × 2 photodetector array lines of centres are no longer perpendicular to the plane of photodetection layer, the center of circle that is laser instrument output facula no longer overlaps with 2 × 2 photodetector array centers, the two relative displacement is that (Δ x, Δ y).Can be understood as two-dimentional tangential force F and cause the deformation of polymer flexibility conductive medium layer horizontal direction, produce respectively the deformation Δ x of x direction and the deformation Δ y of y direction.

On four photodetectors, receiving the photocurrent of exporting after the light wave of laser instrument is to be respectively I ₁, I ₂, I ₃and I ₄, ignore the impact of polymer flexibility conductive medium layer thickness variation on photodetector received optical power, there is (I ₂+ I ₃)-(I ₁+ I ₄) only relevant with the deformation Δ x of x direction, (I ₃+ I ₄)-(I ₁+ I ₂) only relevant with the deformation Δ y of y direction, meet following relation

$r_1\left(\mathrm{\Δx}\right)=\frac{(I_2+I_3)-(I_1+I_4)}{I_{\mathrm{to\; tal}}}---\left(1\right)$

$r_2\left(\mathrm{\Δy}\right)=\frac{(I_3+I_4)-(I_1+I_2)}{I_{\mathrm{to\; tal}}}---\left(2\right)$

Wherein I _total=I ₁+ I ₂+ I ₃+ I ₄be the photocurrent sum of four photodetector outputs, r ₁(Δ x) and r ₂(Δ is y) relative variation of photocurrent.

The component F of two dimension tangential force F in x direction and y direction _xand F _ymeet in the relation of the deformation Δ x of x direction and the deformation Δ y of y direction with polymer flexibility conductive medium layer

$F_x=\frac{\mathrm{\ΔxGS}}{D}---\left(3\right)$

$F_y=\frac{\mathrm{\ΔyGS}}{D}---\left(4\right)$

Wherein G is the tangential modulus of polymer flexibility conductive medium layer, and D is the thickness of polymer flexibility conductive medium layer, and S is lifting surface area.Big or small F and the direction θ of two dimension tangential force F are respectively

$F=\sqrt{F_x^2+F_y^2}---\left(5\right)$

Measure the photocurrent relative variation r of four photodetector x directions and y direction ₁(Δ x) and r ₂(Δ y), calculate deformation Δ x and the Δ y of x direction and y direction according to formula (1) and (2), utilize formula (3), (4) and (5) to calculate the big or small F of two-dimentional tangential force; Utilize formula (6) to calculate the direction θ of two-dimentional tangential force.

Embodiment, selecting PDMS is polymer flexibility conductive medium layer, thickness D=200 μ m, modulus of shearing is G=400kPa, light source layer thickness is 100 μ m, photodetection layer thickness is 100 μ m, the photodetector length of side is a=100 μ m, encapsulation hem width degree d=10 μ m, the radius that laser instrument Output of laser is irradiated to hot spot on 2 × 2 photodetector arraies is R=100 μ m, the area of sensing unit is S=4mm × 4mm, and the x direction of PDMS polymer flexibility conductive medium layer and the largest deformation amount of y direction be | Δ x|| _max=| Δ y|| _max=80 μ m, according to formula this sensor can be calculated and the detection of tangential force within the scope of 0～2.5N can be realized.

In the scope that the hot spot of supposing laser instrument output is R at radius, light intensity is uniformly distributed, and this can be by realizing for lenticule carries out shaping to the light beam of vertical cavity surface emitting laser.Shown in Fig. 3, under two-dimentional tangential force F effect, on four photodetectors, receiving the photocurrent of exporting after the light wave of laser instrument is to be respectively I ₁, I ₂, I ₃and I ₄, the relative variation of x direction and y direction photocurrent is respectively

$r_1\left(\mathrm{\Δx}\right)=\frac{(d+\mathrm{\Δx})\sqrt{R^2-{(d+\mathrm{\Δx})}^2}-(d-\mathrm{\Δx})\sqrt{R^2-{(d-\mathrm{\Δx})}^2}+R^2\arcsin \frac{d+\mathrm{\Δx}}{R}-R^2\arcsin \frac{d-\mathrm{\Δx}}{R}-4\mathrm{d\Δx}}{I_{\mathrm{to\; tal}}}---\left(7\right)$

$r_2\left(\mathrm{\Δy}\right)=\frac{(d+\mathrm{\Δy})\sqrt{R^2-{(d+\mathrm{\Δy})}^2}-(d-\mathrm{\Δy})\sqrt{R^2-{(d-\mathrm{\Δy})}^2}+R^2\arcsin \frac{d+\mathrm{\Δy}}{R}-R^2\arcsin \frac{d-\mathrm{\Δy}}{R}-4\mathrm{d\Δy}}{I_{\mathrm{to\; tal}}}---\left(8\right)$

Wherein

$\begin{array}{c}{I}_{\mathrm{total}}=\mathrm{\π}{R}^2-(d+\mathrm{\Δx})\sqrt{R^2-{(d+\mathrm{\Δx})}^2}-R^2\arcsin \frac{d+\mathrm{\Δx}}{R}-(d-\mathrm{\Δx})\sqrt{R^2-{(d-\mathrm{\Δx})}^2}-R^2\arcsin \frac{d-\mathrm{\Δx}}{R}\\ -(d+\mathrm{\Δy})\sqrt{R^2-{(d+\mathrm{\Δy})}^2}-R^2\arcsin \frac{d+\mathrm{\Δy}}{R}-(d-\mathrm{\Δy})\sqrt{R^2-{(d-\mathrm{\Δy})}^2}-R^2\arcsin \frac{d-\mathrm{\Δy}}{R}+4d^2\end{array}---\left(9\right)$

Fig. 4 and Fig. 5 have provided respectively sensor x direction photocurrent relative variation r ₁relation curve and y direction photocurrent relative variation r with x direction deformation Δ x ₂relation curve with y direction deformation Δ y.In practical application, the photocurrent of measuring four photodetector outputs is to be respectively I ₁, I ₂, I ₃and I ₄; By formula (7), (8) and (9), calculate the photocurrent relative variation r of four photodetector x directions and y direction ₁(Δ x) and r ₂(Δ y), according to the photocurrent relative variation of Fig. 4 and Fig. 5 and the relation curve of deformation, obtains deformation Δ x and the Δ y of x direction and y direction; Utilize formula (3), (4) and (5) to calculate the big or small F of two-dimentional tangential force; Utilize formula (6) to calculate the direction θ of two-dimentional tangential force.For example, record r ₁=0.296, r ₂=-0.436, obtain deformation Δ x=20.0 μ m and the Δ y=-30.0 μ m of x direction and y direction according to Fig. 4 and Fig. 5; Utilize formula (3), (4) to calculate F _x=0.640N, F _x=0.960N; The size that is calculated respectively two-dimentional tangential force by formula (5) and formula (6) is F=1.154N, and direction is θ=-56.3 °.

The above be only preferably embodiment of the present invention, but protection scope of the present invention is not limited to this.Anyly be familiar with, in technical scope that those skilled in the art set forth in the present invention, replacing on an equal basis or changing according to technical scheme of the present invention and inventive concept thereof, all should be encompassed in the row of protection scope of the present invention.

Claims (4)

1. the flexible two-dimentional tangential force touch sensor of optics, is characterized in that:

The flexible two-dimentional tangential force touch sensor of this optics comprises conductive medium layer (2) and the photodetection layer (3) that light source layer (1), flexible polymer form, the arrangement of joining successively from top to bottom;

Laser instrument (11) is positioned at light source layer (1), and the matrix material of light source layer is flexible polymer;

The first photodetector (31), the second photodetector (32), the 3rd photodetector (33) and the 4th photodetector (34) are square, the length of side is a, be arranged in order counterclockwise and form 2 × 2 photodetector arraies, the length of side is 2a, be positioned at photodetection layer (3), the matrix material of photodetection layer is flexible polymer;

The center of laser instrument (11) and the line at 2 × 2 photodetector array centers are perpendicular to the plane of photodetection layer (3).

2. the flexible two-dimentional tangential force touch sensor of optics according to claim 1, it is characterized in that having: laser instrument (11) is vertical cavity surface emitting laser, on its light beam irradiates to 2 of sending × 2 photodetector array, hot spot is circular, and radius is R.

3. the flexible two-dimentional tangential force touch sensor of optics according to claim 1, it is characterized in that having: the first photodetector (31), the second photodetector (32), the 3rd photodetector (33) and the 4th photodetector (34) are slice-shaped photodetector, and the width of encapsulation frame is d.

4. a sensing detection method for the flexible two-dimentional tangential force touch sensor of optics, is characterized in that having following steps:

A. when two-dimentional tangential force F puts on sensor unit, cause polymer flexibility conductive medium layer (2) horizontal direction deformation, produce respectively the deformation Δ x of x direction and the deformation Δ y of y direction, the center of laser instrument (11) and the line of centres of 2 × 2 photodetector arraies are no longer perpendicular to the plane of photodetection layer (3), and on four photodetectors, receiving the photocurrent of exporting after the light wave of laser instrument (11) is to be respectively I ₁, I ₂, I ₃and I ₄, ignore the impact of polymer flexibility conductive medium layer (2) variation in thickness on photodetector received optical power, there is (I ₂+ I ₃)-(I ₁+ I ₄) only relevant with the deformation Δ x of x direction, (I ₃+ I ₄)-(I ₁+ I ₂) only relevant with the deformation Δ y of y direction, meet following relation

$r_1\left(\mathrm{\Δx}\right)=\frac{(I_2+I_3)-(I_1+I_4)}{I_{\mathrm{to\; tal}}}---\left(1\right)$

$r_2\left(\mathrm{\Δy}\right)=\frac{(I_3+I_4)-(I_1+I_2)}{I_{\mathrm{to\; tal}}}---\left(2\right)$

Wherein I _total=I ₁+ I ₂+ I ₃+ I ₄be the photocurrent sum of four photodetector outputs, r ₁(Δ x) and r ₂(Δ is y) relative variation of photocurrent.

B. the component F of two-dimentional tangential force F in x direction and y direction _xand F _ymeet in the relation of the deformation Δ x of x direction and the deformation Δ y of y direction with polymer flexibility conductive medium layer (2)

$F_x=\frac{\mathrm{\ΔxGS}}{D}---\left(3\right)$

$F_y=\frac{\mathrm{\ΔyGS}}{D}---\left(4\right)$

Wherein G is the tangential modulus of polymer flexibility conductive medium layer (2), and D is the thickness of polymer flexibility conductive medium layer (2), and S is lifting surface area.Big or small F and the direction θ of two dimension tangential force F are respectively

$F=\sqrt{F_x^2+F_y^2}---\left(5\right)$

C. measure the photocurrent relative variation r of four photodetector x directions and y direction ₁(Δ x) and r ₂(Δ y), calculate deformation Δ x and the Δ y of x direction and y direction according to formula (1) and (2), utilize formula (3), (4) and (5) to calculate the big or small F of two-dimentional tangential force; Utilize formula (6) to calculate the direction θ of two-dimentional tangential force.