KR100860763B1 - Plastic Thin Film Waveguide and Anti-Pinch Sensors with thereof - Google Patents

Abstract

The present invention relates to a thin film optical waveguide that can be manufactured by molding a plastic material and an anti-fogging sensor using the same. Plastics for optical devices having excellent optical signal transmission characteristics have various refractive indices by controlling constituent molecular components. By using this, if the refractive index difference between the core constituting the optical waveguide and the cladding material is made very small, a highly sensitive optical sensor can be produced in which the optical signal changes significantly even when small objects collide from the outside. The proposed optical sensor can maintain a single mode even if the size of the optical waveguide core is made very large, which makes it easy to implement optical coupling with components such as an LED light source or a photo detector. In addition, the limit of the light waves traveling along the optical waveguide is very low, so that the phenomenon caused by an object having a large curvature can be detected without a separate optical fiber deformation part. These characteristics make it suitable for implementing distributed optical sensors that can measure the phenomena occurring at various points at once. This sensor has the advantage of being able to mass-produce using low cost production process developed for plastic material molding.

Anti-fog sensor, plastic, optical waveguide, distributed, optical sensor, large core, optical waveguide, anti-pinch, sensor, plastic, optical, waveguide, distributed, large core

Description

Plastic thin film optical waveguide, its manufacturing method and anti-fogging sensor using the optical waveguide {Plastic Thin Film Waveguide and Anti-Pinch Sensors with

1 is a view showing a plastic thin film optical waveguide and the anti-jamming sensor using the same according to the present invention.

2 and 3 is a graph comparing the change in the output light due to the bending of the optical waveguide according to the present invention through a BPM simulation.

4 and 5 are views showing an application example of the present invention.

<Description of the symbols for the main parts of the drawings>

1. Optical waveguide

2. Light source

3. Photodetector

4. External pinched object

5. Bending of the optical waveguide caused by the pinch

6. Waveguide proceeding with total reflection

7. Radiated light from the curved optical waveguide

11. Upper cladding

12. Core

13. Lower cladding

21. pinched object

22. Plastic film optical waveguide pinch sensor

23. Car Window Frames

24. Car windows

25. Automatic opening and closing door

26. Door frame

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an anti-fogging sensor that can prevent an accident caused by a part of a body or a portable object frequently occurring in a subway or an elevator, and more particularly, a method of manufacturing a plastic thin film optical waveguide. And to provide an anti-jamming sensor using the plastic thin film optical waveguide.

Recently, the opening and closing of a car window is made possible by a single automated switch operation, so that the accident of the occupant's body in the window is increasing. Anti-jamming sensor is a part necessary to prevent accidents caused by part of human body or belongings that occur in car windows, subway car doors, elevator doors, etc., and various types of products have been researched and developed. Conventional methods for preventing such accidents have been widely used to measure the load of mechanical sensors or motors, and recently, shadow detection type optical sensors used in elevator doors can be seen. Among these products, the sensor that detects the jamming phenomenon by using the change of the optical signal can withstand the electric shock from the outside, and there is no gradual deterioration in performance even when the sensor surface is touched and it is easy to operate as a distributed sensor. Have

The most widely studied form as an optical sensor is a method of using an optical fiber to monitor the loss of the output optical signal generated when an object is caught from the outside. [See Leitner Horst, US 20005173886] In this case, a method of irregularly arranging a high refractive index cladding material on the outside of the optical fiber core is used in order to make the waveguide light traveling along the optical fiber react sensitively by externally transmitted deformation. have.

In some cases, optical fibers may be manufactured using materials having three types of refractive indices in order to fabricate an optical fiber sensor that is sensitive to external minute distortion signals. [R. Gerhard et al., US2005005706] A material having a refractive index higher than the core refractive index of the optical waveguide is selected as the cladding, and a material having a refractive index lower than the core refractive index is interposed therebetween. As a result, the waveguide normally proceeds properly, but when pressure is applied from the outside, the core comes into contact with the high refractive index cladding, thereby guiding the waveguide light to the outside. By using such optical fiber, we proposed a sensor that can monitor the phenomena that can occur in various parts of the car.

However, this special type of optical fiber causes the unit price of the product to increase.

A method has been proposed to make anti-fogging sensors without making the shape of the optical fiber special. [K. Makoto, Hitachi Cable, JP5126659]

The general optical fiber is designed so that the loss of the waveguide light does not occur even when the optical fiber is bent in a radius of about 1 cm. This is because the difference in refractive index between the fiber core and the cladding is made as large as 0.3% for single mode fiber. Because of this, the loss of optical fiber does not begin until the radius is very small. Therefore, even if a part of a human body having a radius of several centimeters directly presses the optical fiber to generate curvature, it cannot induce a change in the optical signal. For this reason, the anti-vibration sensor using an optical fiber requires an optical fiber deformation part capable of bending the optical fiber with a small curvature when an object is caught from the outside. This is a disadvantage in that the fiber-optic deformable parts must be installed very densely in order to make a distributed sensor that detects entanglement at successive points where an optical fiber is installed.

In relation to the manufacturing method of the optical waveguide, since the plastic film optical waveguide must be able to bend and generate curvature when contacted with an external object, it is not suitable to use a general optical waveguide fabrication process manufactured on silicon or an organic substrate. A method for fabricating an optical waveguide on a flexible substrate has also been studied, but the manufacturing process is complicated and is not suitable for mass production. [W. H. Steier et al., US 2005/0249445 A1].

An object of the present invention to solve this problem is to provide an optical sensor that can detect the jamming phenomenon of the external object using the plastic film optical waveguide.

Another object of the present invention is to produce a plastic film optical waveguide having a large core optical waveguide structure having a small difference in refractive index between the core and the cladding, and thus a distributed optical sensor capable of sensitively measuring the seizure of an external object without a separate optical waveguide deformation component. It is in constructing.

Another object of the present invention is to easily attach a low-cost light emitting diode and a photodiode using a plastic film optical waveguide made of a large core optical waveguide structure, and to easily install the sensor by fabricating a sensor as a module and to wear due to repeated contact. It is possible to manufacture the anti-fog light sensor with little cost.

Still another object of the present invention is to enable a plastic optical waveguide to be manufactured at low cost by using a roll-to-roll process.

An anti-fogging sensor using a plastic thin film optical waveguide according to one aspect of the present invention for achieving the above object, and a plastic film-like core for guiding light therein with a constant refractive index, and formed on the upper and lower portions of the core A plastic thin film optical waveguide composed of upper and lower claddings having different refractive indices as a core-like material; A light source unit for injecting a light source into the optical waveguide; It includes a photo detector for detecting the amount of light output from the optical waveguide.

Preferably, the core is characterized in that the single mode optical fiber.

Preferably, the core and the upper and lower cladding are each made of a polymer material, and the difference in refractive index between the polymer material constituting the core and the polymer material constituting the cladding is less than 0.1%.

Preferably, the core is characterized in that more than twice as large as a typical single mode optical fiber.

According to another aspect of the present invention, there is provided a method of manufacturing a plastic thin film optical waveguide, in which a polymer film to form a core is released from a roll; Coating the cladding on top and bottom of the core film to cure the cladding; Cutting to divide into a band having a width of about 1 mm using a blade.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

1 is a view showing a plastic thin film optical waveguide and the anti-jamming sensor using the same according to the present invention. As shown in FIG. 1, the anti-fogging sensor has a plastic film-like core 12 having a constant refractive index and guiding light therein, and formed on upper and lower portions of the core and having different refractive indices as the same material as the core. A plastic thin film optical waveguide (1) composed of upper and lower claddings (11) and (13) having respective ones; A light source unit 2 for injecting a light source into the optical waveguide; It consists of a photodetector 3 which detects the quantity of light output from the said optical waveguide. The light emitted from the light source unit 2 is aligned to be attached to the plastic film optical waveguide 1, and the light passing through the optical waveguide 1 is detected in the output unit using the photodetector 3.

Part of the waveguide 6 leaks to the outside due to deformation of the optical waveguide caused by the object 4 being caught in a portion of the optical waveguide 1 in the jamming sensor (7) and the intensity of the output light is changed so that It can sense the jamming of objects in all parts.

On the other hand, the plastic thin film optical waveguide 1 may be configured in a single mode. In this manner, the single mode of the optical waveguide has much less loss than the multi-mode optical waveguide, and since there is almost no distortion (distortion) of the signal, more accurate sensing condition is sensed and safety is ensured.

On the other hand, the plastic film optical waveguide 1 can be manufactured using a polymer material, and at this time, the refractive index of the polymer material forming the core part 12 and the upper and lower cladding parts 11 and 13 of the optical waveguide is adjusted to be relative. The refractive index difference may be configured to be 0.1% or less. The refractive index of the core portion and the cladding portion may be realized through blending of polymer materials. The optical waveguide 1 is made of a material having a small refractive index difference, and thus the waveguide light is easily prevented even from a small change applied from the outside. It can be used as a sensor that can measure the jamming of the object sensitively. In addition, the localization of the light waves traveling along the optical waveguide is very low, so in the case of an object with a large curvature radius, the optical waveguide can be transformed into a small radius so that a change in the optical power can be sensed without the need for a separate component. Can be. This makes it possible to sense the phenomena occurring in all parts of the optical sensor at once and can be used as a distributed sensor, and there is an example of manufacturing an optical attenuator using this. M.-C. Oh et al., IEEE Photonics Technology Letters, Vol. 17, pp. 1890-1892, 2005; In addition, since the optical waveguide 1 is manufactured using a material having such a small refractive index difference, the size of the optical waveguide core 12 is very large to satisfy the single mode condition. And optical waveguides that propagate only a single mode for thicknesses greater than about 25 um. [M.-C. Oh et al., Optics Communications, vol. 246, pp. 337-343, 2005] Through such a structure, the efficiency of coupling the input light to the optical waveguide can be improved, and the optoelectronic devices can be easily aligned to the input / output parts.

On the other hand, the anti-jamming sensor may be manufactured as a single module of the plastic thin film optical waveguide 1, the light source unit 2 and the photodetector (3). It is advantageous in terms of installation by manufacturing as one module.

On the other hand, as the light source unit 1 can be used a low-cost light-emitting diode (LED) that has recently been rapidly developed in technology, the photodetector 3 has a dozens of the area of the detection unit is similar to the size of the optical waveguide core 12 It can be manufactured using a photodiode having a micrometer thickness. Low cost LEDs and PDs can be used to produce cost-competitive products.

Meanwhile, when manufacturing an optical device using a plastic material, a roll-to-roll process developed for producing a plastic film product may be used. When the polymer film that will form the core is released from the first roll, the next step is to cure the heat-curable or UV-curable polymer on the top and bottom of the core film to cure the film and the optical waveguide is completed. The film optical waveguide is completed when the cut is divided into strips having a width of about mm. It is possible to mass-produce using the roll-to-roll process and UV-cured plastics, which are typical plastic film processing technologies, and have the possibility of lowering the cost of the product at a very low cost.

Hereinafter, in accordance with the above embodiment, the fabrication process using the plastic thin film optical waveguide specifically, the experimental experiment and the specification shown by the actual measurement and the application example of the present invention are exemplified.

In general, the squeeze that can occur in an automated door is caused by a finger or limb jam. In this case, the size of the radius of curvature that the pinch sensor should detect will be approximately 5 mm to 50 mm. Therefore, in this design process, it is meaningful to calculate the attenuation of light waves that occur when the curvature of the optical waveguide is about 5 mm or 50 mm.

The loss of the guided light due to the bending caused by the object being caught in the plastic optical waveguide is investigated through the simulation using the Beam Propagation Method (BPM) to design the device structure. The BPM method is a numerical method for analyzing the propagation of light waves. It is a method of analyzing the propagation of waves through paraxial approximation from the Maxwell equation.

2 and 3 are graphs comparing the change of the output light due to the bending of the optical waveguide according to the present invention through BPM simulation, and FIG. 2 is a case of using a conventional optical fiber and a proposed plastic thin film light in the fabrication of an anti-fogging sensor. It is the result of comparing the change of the output light due to the bending of the optical waveguide generated by an object having a radius of 5 mm similar to a finger in the case of using the waveguide through the BPM simulation. In addition, Figure 3 shows the output due to the bending of the optical waveguide caused by the object having a radius of 50 mm similar to the arm or leg in the case of using a general optical fiber and the proposed plastic thin film optical waveguide in the fabrication of the anti-fogging sensor The change of light is compared through the BPM simulation.

FIG. 2 shows the attenuation of the optical signal that appears when the pinch is generated by an object having a radius of curvature of 5 mm. Comparing the two optical waveguides, the results obtained by performing BPM simulations for a typical optical fiber with a width of 8 um and a refractive index difference of 0.005 and a large core optical waveguide with a width of 25 um and a refractive index difference of 0.001 Is showing. From the results, it can be seen that the pinch phenomenon caused by an object having a radius of curvature of 5 mm causes attenuation of the output light so that the object can be detected.

On the other hand, Figure 3 shows the results for the case that the radius of curvature is 50 mm. In this case, a large-core optical waveguide with a difference in refractive index of 0.001 shows a significant attenuation of the output light when a displacement of 10 um or more occurs. However, for a general optical fiber having a difference in refractive index of 0.005, the displacement is 100 um. Even if it is abnormal, it can be seen that no loss of the guided light occurs. This is because in the case of a general optical fiber, the difference in refractive index between the core and the cladding is sufficiently large that even if a bend of about 50 mm occurs, no radiation of light waves occurs regardless of the magnitude of displacement. In conclusion, when an object with a large radius of curvature such as an arm or a leg is in close contact with the pinch sensor, the sensor using the general optical fiber cannot be detected, but the sensor using the proposed plastic film optical waveguide structure can be detected.

4 and 5 are views showing an application example of the present invention, Figure 4 is a car window, Figure 5 is equipped with an anti-fog sensor in the subway automatic door to detect the possible phenomenon that can occur in a continuous area covered with a plastic optical waveguide An application example of a distributed sensor is shown.

In order to detect the pinch phenomenon using the film optical waveguide, as shown in FIG. 4, the film optical waveguide 22 is attached to the vehicle window frames 23 and 24 or the closed portions 25 and 26 of the automatic door of FIG. 5. Just do it. It is necessary to attach to the surface which is not too hard so that the film optical waveguide 22 can easily form curvature when the external object 21 is contacted. However, fiber-optic deformable parts that are needed in ordinary fiber are not needed. As such, when the film optical waveguide 22 is attached to the film optical waveguide 22, the film optical waveguide 22 may have a function as a distributed sensor capable of detecting a pinch signal that may occur in all portions passing by the optical waveguide.

As described above, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, the plastic optical waveguide proposed in the present invention is manufactured to have a difference in refractive index of less than 0.1% between the polymer material constituting the core and the polymer material constituting the cladding, so that the loss of the waveguide light is very sensitive to external stimuli. As a result, the optical waveguide structure is very suitable for fabricating an optical sensor that can detect even minute pinching. The large-core single-mode optical waveguide makes the process of connecting the light source and the photodetector very easy, allowing manual assembly of the product without the need for expensive equipment, thereby increasing the price competitiveness of the sensor module. Since the proposed optical sensor uses plastic material, it is possible to apply low-cost mass production technology such as roll-to-roll method. Compared to the structure using a special type of optical fiber, the configuration of the module is simple, so that it can be a product that can compete with the electronic sensor in the market. It will be a product that can pioneer the market as an optical sensor that can be applied to various applications that have not been adopted due to the high price so far.

Claims (6)

A plastic film core having a constant refractive index and guiding light therein; And a plastic cladding formed on upper and lower portions of the core, the plastic cladding having a refractive index different from that of the core. The method of claim 1, Wherein said core is a single mode optical waveguide. The method of claim 2, The core and the upper and lower cladding are each composed of a polymer material, And a refractive index difference between the polymer material constituting the core and the polymer material constituting the cladding is 0.0001% to 0.1%. The method of claim 3, wherein The core is a plastic thin film optical waveguide, characterized in that 2 to 4 times larger than a typical single mode optical fiber. A plastic film optical waveguide including a plastic film-type core having a constant refractive index and guiding light therein, and a plastic cladding formed on upper and lower portions of the core and having a refractive index different from that of the core; A light source unit for injecting a light source into the optical waveguide; Anti-jamming sensor comprising a; a photo detector for detecting the amount of light output from the optical waveguide. In the manufacturing method of a plastic thin film optical waveguide, The polymer film which will form the core is released from the roll; Coating the cladding on top and bottom of the core film to cure; and Method of manufacturing a plastic thin film optical waveguide comprising the step of cutting to divide into a band having a width of about 1 mm using a blade.

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