JP2015184404A - Contact detection sensor and contact detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost contact detection sensor capable of detecting, with high sensitivity, the presence of a contact.SOLUTION: A thin film (4a) including aluminium is formed upon a base material (2), and the base material (2) having the thin film formed thereon is subjected to hot-water treatment to form a fine-uneven-structure film (4) having, as a main component thereof, an alumina hydrate. The reflectance of the fine-uneven-structure film (4) with respect to prescribed wavelengths in the visible-light range incident from the front-surface side is set to be at least 4%.

Description

  The present invention relates to a sensor for determining presence / absence of contact, and more particularly to a contact detection sensor for detecting presence / absence of contact based on a change in spectral reflectance of the surface and a contact detection method using the contact sensor.

Conventionally, as a sensor capable of measuring the pressure distribution over a large area, a film in which a color former layer containing a microcapsule containing a color former is applied to a support is overlaid on a film in which a developer is applied to the support, In other words, a color developer is adsorbed on a developer by destroying the microcapsules and colored by a chemical reaction (for example, see Patent Document 1).
Such a sensor is used to evaluate the smoothness and parallelism of a manufacturing apparatus for optical components and electronic components.

  On the other hand, in Patent Document 2, a fine concavo-convex structure on the surface of anodized alumina is transferred, a fine concavo-convex structure is formed on the surface of the substrate, and scattered light or reflected light accompanying the destruction of the fine concavo-convex structure resulting from the application of pressure, A pressure sensor of the type that detects transmitted light is disclosed. This method is more sensitive than the color development method based on the destruction of the microcapsules, and has an advantage that the pressure distribution in a minute region can be detected. In the case of the microcapsule method, in order to detect a low pressure, the particle size of the microcapsule needs to be several tens of μm, and it is difficult to have a position resolution lower than that. On the other hand, in the type that detects the destruction of the fine concavo-convex structure, such a trade-off regarding sensitivity and size does not occur.

  On the other hand, Patent Document 3 includes an antireflection structure having a fine concavo-convex structure as a contact detection sensor that can easily detect the presence or absence of contact by a third party, and whether or not there is contact based on a change in reflectance. There has been proposed a contact detection sensor for identifying the above. The contact detection sensor described in Patent Document 3 does not detect a change in reflectance due to the destruction of the fine concavo-convex structure, and adheres to sebum, sweat, dirt on the skin, etc. when the human body contacts the antireflection structure. Thus, the presence or absence of contact is identified by utilizing the increase in reflectance.

JP 50-126479 A JP 2009-257946 A JP 2005-335379 A

  The contact detection sensor having a fine concavo-convex structure disclosed in Patent Document 2 is manufactured by transferring a fine concavo-convex structure on the surface of an anodized alumina by an imprint method. For this reason, it is necessary to prepare a master, and in addition to the transfer cost, the cost of preparing the master is generated. Moreover, when producing by optical imprinting, the fine concavo-convex structure can be formed only on a transparent substrate capable of optical imprinting.

  The contact detection sensor disclosed in Patent Document 3 is a base material provided with an antireflection structure on a part of its surface. For example, a pattern is drawn on a quartz glass substrate or the like by a method such as electron beam drawing, and dry etching or the like is performed. After processing and forming a master mold that has been precisely processed into the same shape as the antireflection structure in advance, the master mold is used to press-mold a material such as heat-softened glass material or acrylic resin. An antireflection structure molding die is manufactured, and is further manufactured by press molding a material such as acrylic resin. The manufacturing method described in Patent Document 3 requires the cost of master production and the cost of structure transfer as in the case of Patent Document 2.

  The present invention has been made in view of the above circumstances, and can be manufactured at low cost, and can be manufactured regardless of whether the substrate is transparent or opaque, and provides a highly sensitive contact detection sensor. To do.

The contact detection sensor of the present invention comprises a base material and a fine concavo-convex structure film formed on the surface of the base material,
The fine concavo-convex structure film is made of a material mainly composed of alumina hydrate,
The reflectance with respect to a predetermined wavelength in the visible light region incident from the surface side of the fine concavo-convex structure film is 4% or more.

  The reflectance of 4% or more for a predetermined wavelength in the visible light region does not have to be 4% or more over the entire visible light region. For example, the reflectance at a predetermined wavelength of 450 nm, 500 nm, or the like. It may be 4% or more. In addition, the reflectance here is a reflectance as a contact detection sensor including a fine concavo-convex structure film and a base material. When the base material is a metal or a semiconductor, the reflectance is usually sufficiently high. .

  It is preferable that an intermediate layer serving as an optical interference layer is provided between the substrate and the fine concavo-convex structure film.

  The base material may be made of an opaque material.

  The contact detection method of the present invention detects a region where the fine uneven structure has changed due to pressure applied to the contact detection sensor of the present invention by measuring scattered light, reflected light or transmitted light from the contact detection sensor. This is a contact detection method for identifying the presence or absence of contact.

  The contact detection sensor of the present invention comprises a base material and a fine concavo-convex structure film formed on the surface of the base material, and the fine concavo-convex structure film is made of a material mainly composed of alumina hydrate. Therefore, the fine concavo-convex structure film can be obtained by an extremely simple process of forming a thin film containing aluminum and hydrothermal treatment. The fine concavo-convex structure film made of a material whose main component is alumina hydrate is a highly sensitive sensor because it is very weak to mechanical force, its structure collapses even with a slight force, and its spectral characteristics change. . In addition, since the reflectance with respect to a predetermined wavelength in the visible light region incident from the surface side of the fine concavo-convex structure film is 4% or more before the pressure is applied, it is easy to identify the change in the spectral characteristics of the reflected light. It can be carried out.

  In addition, since the fine concavo-convex structure film made of a material mainly composed of alumina hydrate has high heat resistance, when combined with a heat-resistant substrate, a high pressure can be obtained in a high temperature environment. It is also possible to obtain a pressure sensor that can be detected with positional resolution.

It is a perspective view which shows schematic structure of the contact detection sensor of embodiment of this invention. It is a partially expanded view of the contact detection sensor shown in FIG. It is sectional drawing which shows typically the uneven structure after a pressure is applied to the surface of a contact detection sensor. It is a figure which shows the manufacturing process of a contact detection sensor. It is a figure which shows the wavelength dependence of the reflectance before and behind rubbing of a contact detection sensor.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view schematically showing a configuration of a contact detection sensor according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a part II of the sensor 1 shown in FIG.
As shown in FIGS. 1 and 2, the contact detection sensor 1 of the present embodiment is formed by laminating an intermediate layer 3 and a fine concavo-convex structure film 4 mainly composed of alumina hydrate on a base material 2 in this order. .

  When a human touches the fine concavo-convex structure film 4 or when an object comes into contact with the fine concavo-convex structure film 4, the fine concavo-convex on the surface is damaged. The reflectance (spectral characteristics) for light incident from the fine concavo-convex structure film 4 side varies greatly between a normal fine concavo-convex structure and a damaged fine concavo-convex structure. For example, by rubbing the surface of the fine uneven structure film 4, the fine unevenness on the surface becomes a layer 4 b having a smooth surface whose cross-sectional schematic diagram is shown in FIG. 3. The petal-like fine irregularities shown in FIG. 2 have a gentle undulation as shown in FIG. 3, and the spectral characteristics with respect to the irradiated light greatly change with this structural change. The presence or absence of contact can be detected by detecting the change.

  The fine concavo-convex structure film mainly composed of hydrate of alumina is very sensitive to contact and is broken by a slight pressure. Therefore, it is possible to detect contact due to a slight force with high sensitivity.

  The contact detection sensor of the present invention has a reflectance of 4% or more with respect to a predetermined wavelength in the visible light region before use. The reflectance does not need to be 4% or more over the entire visible light range, and may be 4% or more at a predetermined wavelength such as 450 nm and 500 nm, for example. Since the reflectance is a reflectance as a contact detection sensor including a fine concavo-convex structure film and a substrate, the reflectance is usually sufficiently high when the substrate is opaque. On the other hand, even if the base material is transparent, if the reflectance is about 4%, it becomes easy to identify a change in reflectance accompanying a subsequent structural change. For example, a contact detection sensor having a reflectance peak of 4% or more at a wavelength of 450 nm and having a reflectance peak of 4% or more at a wavelength of 540 nm as a result of contact is caused by a change in reflection color from blue to green. The presence or absence of contact can be determined visually. On the other hand, if the peak reflectance before the contact is lower than 4%, the reflected color before the contact cannot be clearly recognized, and even if the reflected light can be visually recognized after the contact, whether it is caused by the contact or the light source It is not possible to determine whether this is due to the way you see it. Therefore, the contact detection sensor of the present invention preferably has a reflectance peak of 4% or more with respect to a predetermined wavelength in the visible light region before use.

  As the base material 2, a plate material, a film material, or the like made of any one of glass, resin, metal, and semiconductor can be used. Specifically, as glass, quartz glass, soda glass, sapphire glass, and other general glass materials can be used. As the resin, polyethylene terephthalate film, polyethylene naphthalate film, polyimide film and other general resin materials can be used. As the metal, general metal materials such as aluminum, copper, chromium, iron, and stainless steel can be used. Silicon, germanium, or the like can be used as the semiconductor. In the contact detection sensor of the present invention, the fine concavo-convex structure film is a hydrate of alumina, and it is not necessary to irradiate UV light from the back surface of the substrate, which is necessary when producing an imprint method as in Patent Document 2. As a base material, not only a transparent material but also an opaque material such as a metal can be used.

  The intermediate layer 3 is a layer that functions as an optical interference layer, and is preferably transparent to the detection wavelength for detecting the presence or absence of contact. The intermediate layer 3 preferably has an optical film thickness of 8 / λ or more at the detection wavelength λ. More preferably, it is 4 / λ or more. Moreover, it is desirable to have a refractive index larger than the refractive index of the base material 2.

  The intermediate layer 3 is an optical interference layer composed of one layer or a plurality of layers provided between a base material and a layer of a material containing an aluminum element in order to emphasize a change in optical characteristics due to the presence or absence of a fine concavo-convex structure. For this intermediate layer, oxides and nitrides and oxynitrides containing at least one element of zirconium, tantalum, niobium, aluminum, silicon, and lanthanum are used as known materials used as optical thin films. it can. Alternatively, an organic compound such as a fluororesin can be used.

  By providing the intermediate layer 3, it is possible to increase the change in reflectance between the case of the normal fine concavo-convex structure and the case of the damaged fine concavo-convex structure as compared with the case where the intermediate layer 3 is not provided. If the change in the reflectance before and after the destruction of the fine concavo-convex structure can be increased, the measurement apparatus for detecting the change can be simplified and the cost can be reduced. Also, visual identification is possible.

  Note that the fine uneven structure film 4 may be formed directly on the base material 2 without providing the intermediate layer 3. Even if the intermediate layer 3 is not provided, the spectral characteristics with respect to the incident light change before and after the breakage of the fine concavo-convex structure. Therefore, the presence or absence of breakage, that is, the presence or absence of contact can be identified by detecting the change.

The fine concavo-convex structure film 4 is mainly composed of alumina hydrate. The alumina hydrate is expressed as boehmite (Al ₂ O ₃ .H ₂ O or AlOOH) which is an alumina monohydrate. Bayerlite (represented as Al ₂ O ₃ .3H ₂ O or Al (OH) ₃ ), which is alumina trihydrate (aluminum hydroxide).

  The irregularity period (average pitch) of the fine concavo-convex structure film 4 is sufficiently smaller than the shortest wavelength in the used wavelength range that is the wavelength range of incident light. In the fine concavo-convex structure film 4, the pitch is the distance between the vertices of the nearest adjacent convex portions across the concave portion, and the depth is the distance from the convex portion vertex to the bottom of the adjacent concave portion. The period of the fine irregularities is on the order of several tens of nm to several hundreds of nm.

  The fine concavo-convex structure film has a structure that becomes sparser as it gets away from the base material (the width of the void corresponding to the concave portion becomes larger and the width of the convex portion becomes smaller), and the refractive index becomes smaller as it gets away from the base material. Become.

  The average pitch of the unevenness can be obtained by, for example, taking a surface image of the fine uneven structure with an SEM (scanning electron microscope), performing image processing, binarizing, and performing statistical processing. Similarly, the film thickness of the concavo-convex structure film can be obtained by taking a cross-sectional image of the fine concavo-convex structure film and processing the image.

With reference to FIG. 4, the manufacturing method of the contact detection sensor 1 is demonstrated easily.
First, the base material 2 is prepared, and the intermediate layer 3 is formed on the base material 2. The intermediate layer 3 may be a single layer or a multilayer of two or more layers.
Thereafter, a thin film of a material containing aluminum is formed on the intermediate layer 3. Examples of the material containing aluminum include metal aluminum and aluminum oxide.
Note that when Al ₂ O ₃ is formed as a thin film of a material containing aluminum, the thickness is desirably 5 nm or more. In order to increase the reflectance change at the time of use, it is more desirable that the Al ₂ O ₃ film to be formed has a thickness of 40 nm or more.

  When the intermediate layer 3 is not provided, a thin film of a material containing aluminum is directly formed on the base material 2. Moreover, when the base material 2 is aluminum, it is not necessary to form a thin film of a material containing aluminum, and the base material 2 itself may be used in the following processing.

  Thereafter, the substrate 2 (or aluminum substrate) on which the thin film 4a made of an aluminum element-containing material is formed is subjected to hydrothermal treatment to form a fine relief structure 4 mainly composed of alumina hydrate on the surface. can do. As the hydrothermal treatment, it is preferable to immerse in warm water in the range of 60 to 100 ° C. for 1 minute or more. For stabilization of the treatment, it is preferable to immerse for 3 minutes or more.

  The contact detection sensor of the present invention can be manufactured by the above procedure. The fine concavo-convex structure mainly composed of alumina can be obtained by a very simple method. Unlike the case of using the imprint method as described in Patent Document 2 described above, irradiation with active energy rays for resist curing is performed. Since it is not necessary, the substrate does not require light transmittance, and can be appropriately selected from a wide range of materials according to the application. Here, in order to form the reflectance with respect to the predetermined wavelength λ in the fine concavo-convex structure film to be larger than 4%, one or more intermediate layers having a refractive index larger than the refractive index of the material constituting the fine concavo-convex structure, It is preferable to form the film so that the optical path length is λ / 20 or more with respect to the wavelength λ of interest. Furthermore, it is preferable to form the intermediate layer with a film thickness such that the optical path length of the intermediate layer is about λ / 4 with respect to the wavelength of interest. Since the refractive index of alumina hydrate is about 1.6 in the visible light region, the refractive index of the intermediate layer is preferably larger than 1.6.

  In the contact detection method using the contact detection sensor having the above-described configuration, a region in which the fine uneven structure of the contact detection sensor has changed is detected by measuring scattered light, reflected light, or transmitted light from the contact detection sensor. It is a method of identifying the presence or absence of When the substrate is transparent, the presence or absence of contact can be identified by measuring the scattered light, reflected light or transmitted light. When the substrate is opaque, the scattered light or reflected light can be measured. The presence or absence of contact can be identified. Although human visual detection is also possible, it may be difficult to visually confirm when the change in reflectance is small or when the change is in a minute region.

  When it is difficult to visually confirm, the reflectance can be measured with a film thickness measuring instrument. In addition, reflectance measurement by a microspectroscopic method may be performed. Alternatively, a light source having one or more wavelengths may be irradiated to obtain a reflectance map with respect to the position.

  For example, an LED light source having a wavelength of 650 nm is diffused, irradiated to a contact detection sensor, and received by an optical sensor using an imaging system such as a digital camera, thereby obtaining a luminance distribution of pixels. Whether or not there is a contact or which part of the contact is detected can be detected because the luminance of the contacted part increases. In addition, the wavelength to irradiate is not restricted to 650 nm, It is desirable to investigate beforehand the wavelength with a large reflectance difference before and behind a contact, and to use the wavelength with a large reflectance difference.

  Alternatively, a map of the scattering intensity with respect to the position may be acquired by irradiating light having one or more wavelengths. For example, collimated light of UV laser light having a wavelength of 405 nm is irradiated to a contact detection sensor at an incident angle of 45 °, and received by an optical sensor using an imaging system such as a digital camera immediately above the contact detection sensor, and the luminance distribution of the pixels is determined. get. It is possible to detect the presence or absence of contact and the distribution of contact points by increasing the scattered light intensity because the structure of the fine uneven structure film of the sensor changes before and after contact, and increasing the brightness of the part where the fine unevenness is destroyed. it can.

  The incident angle and the angle of the imaging system are not limited to the above angles, and can be set as appropriate. When measuring the change in scattered light, it is desirable to use a short wavelength of 550 nm or less because the intensity of the scattered light can be increased.

Since the contact detection sensor can irreversibly record whether or not it is in contact, a member of a manufacturing apparatus that comes into contact with these components in the manufacture of optical components (such as optical films) and electronic components (such as semiconductor elements). It can be used as a means for evaluating the smoothness, parallelism, etc., and as a member for mechanical impact analysis.
It can also be used for security seals and the like, and can also be used for detecting the presence of contact by a third party by sticking to a sealed letter or a storage case.

  Hereinafter, a method for manufacturing the contact detection sensor according to the embodiment of the present invention will be described.

[Example 1]
An S-BSL7 glass substrate (25 mm square, thickness 2.5 mm) was used as the base material. First, an intermediate layer serving as an optical interference layer was formed on the surface of the glass substrate. A ZrO ₂ layer was formed as an intermediate layer by 100 nm electron beam evaporation. This intermediate layer makes it easier to visually recognize the change in reflectance when the fine concavo-convex structure is broken. Next, an Al ₂ O ₃ layer of 80 nm was similarly formed by electron beam evaporation.
After that, when the base material on which the ZrO ₂ layer and the Al ₂ O ₃ layer are formed is immersed in warm water at 70 ° C. for 15 minutes, the outermost alumina thin film becomes an aluminum hydroxide, and the concavo-convex structure by fine plate crystals is formed. Obtained.

The surface of the produced contact detection sensor was wiped (rubbed) with cotton with a force of 0.2 gram weight / mm ² . The wavelength dependence of each reflectance was measured before and after this rubbing. The results are shown in FIG. In FIG. 5, the reflectance before rubbing is indicated by a solid line, and the reflectance after rubbing is indicated by a broken line. It is clear that the spectral characteristics change greatly before and after rubbing. A wavelength of 450 nm to 530 nm at which the reflectance is greatly increased by rubbing is suitable as a wavelength for measuring the presence or absence of contact.

[Example 2]
Using an A4300 film (Toyobo) (50 mm square, 75 μm thickness) as a base material, a ZrO ₂ layer of 100 nm and then an Al ₂ O ₃ layer of 80 nm were formed by electron beam evaporation in the same manner as in Example 1. did. Then, when the base material formed into a film was immersed in 70 degreeC warm water for 15 minutes, the alumina thin film of the outermost layer became an aluminum hydroxide, and the uneven structure by a fine plate-like crystal was obtained.

The surface of the produced contact detection sensor was rubbed with cotton with a force of 0.2 gram weight / mm ² , and the wavelength dependence of the reflectance was measured before and after this rub. As a result, the same change in reflectance as in Example 1 was observed.

[Example 3]
A Si substrate (diameter 50.4 mm, thickness 2.5 mm) was used as the base material. An Al layer of 60 nm was formed on the surface of the Si substrate by RF sputtering. Then, when the base material formed into a film was immersed in 80 degreeC warm water for 10 minutes, the alumina thin film of the outermost layer became an aluminum hydroxide, and the uneven structure by a fine plate-like crystal was obtained.
The surface of the produced contact detection sensor was rubbed with cotton with a force of 0.2 gram weight / mm ² , and the wavelength dependence of the reflectance was measured before and after this rub. As a result, the same change in reflectance as in Example 1 was observed.

DESCRIPTION OF SYMBOLS 1 Contact detection sensor 2 Base material 3 Intermediate | middle layer 4 Fine uneven structure film 4a Thin film containing aluminum

Claims (4)

It consists of a substrate and a fine concavo-convex structure film formed on the surface of the substrate,
The fine concavo-convex structure film is made of a material mainly composed of alumina hydrate,
The contact detection sensor whose reflectance with respect to the predetermined wavelength of the visible light region which injected from the surface side of the said fine concavo-convex structure film is 4% or more.   The contact detection sensor of Claim 1 provided with the intermediate | middle layer used as an optical interference layer between the said base material and the said fine concavo-convex structure film.   The contact detection sensor according to claim 1, wherein the base material is made of an opaque material.   A region in which the fine concavo-convex structure is changed by applying pressure to the contact detection sensor according to any one of claims 1 to 3 is detected by measuring scattered light, reflected light, or transmitted light from the contact detection sensor. A contact detection method that identifies the presence or absence of contact.

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