JP2011107871A - Light reception panel and optical touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light reception panel for preventing any erroneous operation from being generated even when it is used under natural light excluding any influence due to disturbance light components due to natural light even when receiving rays of light collectively introduced through a waveguide through a light receiving element with high sensitivity which receives the rays of light in a near infrared region from a visible light region and an optical touch panel using the light reception panel. <P>SOLUTION: The light reception panel includes: a light receiving element which receives the rays of light in a near infrared region from a visible light region; an optical waveguide coupled to the light receiving element; a transparent panel arranged at the lower side of the optical waveguide; and an adhesive layer for bonding the optical waveguide with the transparent panel, wherein the adhesive layer absorbs the rays of light within the range of wavelength 450-700 nm by 70% or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a disturbance caused by natural light even when light collectively guided through a waveguide is received through a highly sensitive light receiving element that receives light from the visible light region to the near infrared region. The present invention relates to a light receiving panel that does not cause a malfunction even when used under natural light by eliminating the influence of light components, and an optical touch panel that uses the light receiving panel.

  Conventionally, various types of optical touch panels in which a plurality of light receiving elements and light emitting elements are arranged on a transparent panel have been proposed, and this type of optical touch panel is described in, for example, Japanese Patent Application Laid-Open No. 2006-59296. As described above, the touch position can be detected by detecting the intensity change of the infrared light emitted from the infrared light emitting element with the infrared light receiving element.

And in this optical touch panel, in order to eliminate the visible light component that is the disturbance light component of sunlight, the window frame-shaped bezel is colored black, or to eliminate the inner infrared component of sunlight. A cover resin is attached to the top surface of the bezel.
Thereby, disturbance due to sunlight is prevented, infrared light emitted from the light emitting element is received by the light receiving element with high accuracy, and the accuracy of the optical touch panel is improved.

JP 2006-59296 A

  By the way, in the optical touch panel described in Patent Document 1, a plurality of light emitting elements are arranged on one of two opposing sides of a rectangular bezel, and a plurality of light emitting elements are opposed to each other on the other side. In the same manner, a plurality of light emitting elements are arranged on one of the remaining two opposite sides, and a plurality of light receiving elements are arranged on the other side so as to face each light emitting element. Has been.

  However, such a configuration requires many light emitting elements and light receiving elements corresponding to the resolution of the optical touch panel, and as a result, there is a problem that the cost of the optical touch panel cannot be reduced.

  Under such circumstances, an optical waveguide is used on the light receiving element side, and light emitted from each light emitting element is transmitted through each core of the optical waveguide, and light from each core is coupled to one end of each core. It is conceivable to receive light through the element. By adopting such a configuration, the number of light receiving elements can be significantly reduced.

However, as described above, for example, CMOS (complementary metal oxide semiconductor) image sensors and CCD (Charge Coupled Device) image sensors are the only light receiving elements that can be used by being coupled to each core of the optical waveguide as described above. It is.
Here, the CMOS image sensor and the CCD image sensor are high-sensitivity light receiving elements that receive light from the visible light region to the near infrared region. An optical waveguide is disposed on the light receiving device side and each core of the optical waveguide is disposed. When an optical touch panel using a combined CMOS image sensor or CCD image sensor is used under natural light from sunlight, the light emitted from the light emitting element is generally near infrared light or infrared light. Since each image sensor also detects light in the visible light region, the visible light component in the natural light becomes a disturbance light component to accurately detect near infrared light and infrared light from the light emitting element. Can not be. As a result, when the optical touch panel as described above is used under natural light, there is a problem that malfunction occurs due to a visible light component in natural light, and there is a demand for a solution to such a problem.

As a result of diligent studies to solve the above problems, the inventors of the present invention caused the malfunction when the optical waveguide was bonded to the transparent panel, natural light reflected by the transparent panel and entered the core of the optical waveguide, It was found that this is because the light receiving element senses such light.
Therefore, when a black adhesive that absorbs 70% or more of light in the wavelength range of 450 nm to 700 nm in the visible light region is used as an adhesive layer for bonding the optical waveguide and the transparent panel, it has been found that the above problems can be solved. It was.
Natural light includes light in a wide wavelength range of various wavelengths, but it has been found that the light intensity at wavelengths of 450 nm to 700 nm is high. Based on this, it is possible to provide a light receiving panel excellent in detection sensitivity without causing malfunction even when used under natural light by shielding the wavelength region, and an optical touch panel using the light receiving panel. .

  As described above, the present invention has been made to solve the above-described problems in the prior art, and receives light collectively guided through the waveguide and receives light from the visible light region to the near infrared region. Even when receiving light through a highly sensitive light-receiving element, the light-receiving panel that eliminates the effects of disturbance light components caused by natural light and does not cause malfunction even when used under natural light, and optics that uses the light-receiving panel An object is to provide a touch panel.

  In order to achieve the above object, a light receiving panel according to claim 1 of the present application includes a light receiving element that receives light from a visible light region to a near infrared region, an optical waveguide coupled to the light receiving element, and a bottom of the optical waveguide. A light receiving panel comprising a transparent panel disposed on a side, and an adhesive layer that bonds the optical waveguide and the transparent panel, wherein the adhesive layer emits light in a wavelength range of 450 nm to 700 nm by 70% or more. It is characterized by absorbing.

  An optical touch panel according to claim 2 is a light emitting element that emits light in a near infrared region, a light emitting side optical waveguide coupled to the light emitting element, a transparent panel to which the light emitting side optical waveguide is fixed, A light-receiving element that receives light from the visible light region to the near-infrared region, a light-receiving side waveguide that is bonded to the transparent panel via an adhesive layer facing the light-emitting side optical waveguide, and is coupled to the light-receiving element; The adhesive layer that adheres the light receiving side waveguide to the transparent panel absorbs light in the wavelength range of 450 nm to 700 nm by 70% or more.

  In the light receiving panel according to claim 1, a wavelength belonging to a visible light region in natural light that reflects the transparent panel and enters the optical waveguide through an adhesive layer that bonds the optical waveguide coupled to the light receiving element and the transparent panel. A light-receiving panel that absorbs 70% or more of light in the range of 450 nm to 700 nm, so that even if it is used under natural light, it does not cause malfunction even when used under natural light by eliminating the influence of visible light components. Can be realized.

  The optical touch panel according to claim 2 belongs to a visible light region of natural light that reflects the transparent panel and enters the optical waveguide through an adhesive layer that bonds the optical waveguide coupled to the light receiving element and the transparent panel. Even if light in the range of 450 nm to 700 nm is absorbed by 70% or more, even if it is used under natural light, even if it is used under natural light by eliminating the influence of visible light components, the near red light emitted from the light emitting element It is possible to realize an optical touch panel that reliably detects that light in the outer region is blocked by a finger or the like and does not cause malfunction.

It is sectional drawing which shows typically the light reception panel which concerns on this embodiment. It is sectional drawing which shows typically the optical touch panel which concerns on this embodiment. It is a top view which shows an optical touch panel typically. It is explanatory drawing which shows typically the light interception signal detected when an optical touch panel is touched.

Hereinafter, a light receiving panel and an optical touch panel using the light receiving panel according to the present embodiment will be described with reference to the drawings.
First, the light receiving panel according to the present embodiment will be described with reference to FIG.

[Light receiving panel]
As shown in FIG. 1, a light receiving panel 1 according to this embodiment includes a light receiving element 2 that receives light from the visible light region to the near infrared region, a light receiving side optical waveguide 3 that is coupled to the light receiving element 2, and a light receiving device. A transparent panel 4 disposed below the side optical waveguide 3, and an adhesive layer 5 that bonds the light receiving side optical waveguide 3 and the transparent panel 4, the adhesive layer 5 having a wavelength in the range of 450 nm to 700 nm. The light is absorbed by 70% or more.

  Here, a resin layer 6 that blocks light belonging to the visible light region (wavelength of 380 nm to less than 780 nm) and the near infrared region (780 nm to 2500 nm) is formed on the upper surface of the light receiving side waveguide 3 in the light receiving panel 1. ing. Thereby, it is possible to block the light L <b> 1 due to natural light entering from the upper side of the light receiving side waveguide 3.

Next, each component constituting the light receiving panel 1 will be described.
(1) Light receiving element 2
The light receiving element 2 used in the present invention is an element that receives visible light (wavelength 380 nm or more and less than 780 nm) and light in the near infrared region (wavelength 780 nm to 2500 nm) and converts an optical signal into an electrical signal. Examples of the light receiving element include a CMOS (complementary metal oxide semiconductor) image sensor and a CCD (Charge Coupled Device) image sensor.

(2) Light receiving side optical waveguide 3
The light-receiving side optical waveguide 3 used in the present invention includes a core 3A, an upper cladding layer 3B and a lower cladding layer 3C in which the core 3A is embedded. Further, the end portion (left end portion in FIG. 1) of the core 3 </ b> A is optically coupled to the light receiving element 2. Here, the core 3A is made of a material having a higher refractive index and higher transparency than the respective cladding layers 3B and 3C.
The core 3A is preferably formed from a photosensitive resin having excellent patterning properties. The upper clad layer 3B and the lower clad layer 3C are preferably formed from a photosensitive resin and a thermosetting resin. The maximum refractive index difference between the core 3A and the respective cladding layers 3B and 3C is preferably 0.01 or more, and more preferably 0.02 to 0.2.
The core width (base) of the core 3A is preferably 10 μm to 500 μm, and the core height (height when connecting the midpoint of the core width) is preferably 10 μm to 100 μm. Furthermore, the thickness of each cladding layer 3B, 3C is preferably 10 μm to 5 mm. Each of the cladding layers 3B and 3C may be a single layer or a multilayer.
The light-receiving side optical waveguide 3 configured as described above can be manufactured by any method such as a dry etching method using plasma, a transfer method, an exposure / development method, and a photo bleach method.

(3) Transparent panel 4
The transparent panel 4 is disposed below the light receiving side optical waveguide 3. Here, when the light receiving panel 1 is used as an optical touch panel (described later) in various display devices (for example, attached to a personal computer or a mobile phone), the transparent panel 4 protects the display from scratches and dirt. Also serves as a concession panel.
The transparent panel 4 preferably has a light transmittance of 90% or more in the visible light region, and is, for example, a glass plate or an acrylic plate. The thickness of the transparent panel 4 is preferably 10 μm to 20 mm.

(4) Adhesive layer 5
The adhesive layer 5 for adhering the student-side optical waveguide 3 and the transparent panel 4 to each other has a characteristic of absorbing 70% or more of light in the wavelength range of 450 nm to 700 nm, and is formed from a black adhesive. In the light receiving panel 1, if the adhesive layer 5 having such a light absorption property is used, 70% or more of light in a wavelength range of 450 nm to 700 nm belonging to the visible light region of the light L 2 reflected by the transparent panel 4 is absorbed. It is possible to prevent the light L2 from entering the core 3A of the light receiving side waveguide 3. Thereby, the disturbance component which belongs to the visible light area | region in natural light can be excluded, and it can prevent that the light receiving element 2 detects the light of visible light area | region, and malfunctions.
Here, the light transmittance of the adhesive layer 5 can be appropriately adjusted, for example, by mixing a light-shielding filler into the base adhesive. The adhesive 5 is not particularly limited, but is preferably an epoxy adhesive. This is because epoxy adhesives have strong adhesive strength and high water resistance. Examples of the light-shielding filler include carbon black, activated carbon, graphite, and black pigment. The adhesive layer 5 may contain a near-infrared absorbing dye in addition to the light-shielding filler. Moreover, the mixing amount of the light-shielding filler can be appropriately adjusted so that the light transmittance of the obtained adhesive layer 5 falls within the above range.

[Optical touch panel]
Although there is no restriction | limiting in particular as a use of the light reception panel 1 comprised as mentioned above, The optical touch panel using this light reception panel 1 is demonstrated based on FIG.2 and FIG.3.
2 and 3, the optical touch panel 7 according to this embodiment is transparent through an adhesive layer 8 so as to face the light receiving side optical waveguide 3 in the light receiving panel 1 in addition to the light receiving panel 1. It has a light emitting side optical waveguide 9 bonded to the panel 4. The light-emitting side optical waveguide 9 has a core 9A, an upper clad layer 9B in which the core 9A is embedded, and a lower clad layer 9C. Further, the end portion (the right end portion in FIG. 2) of the core 9 </ b> A is optically coupled to the light emitting element 10. Here, the core 9A is made of a material having a higher refractive index and higher transparency than the clad layers 9B and 9C. The light emission side optical waveguide 9 is disposed at a position facing the light reception side optical waveguide 3 coupled to the light receiving element 2 (see FIG. 3).
The light emitting element 10 emits light L3 in the near infrared region, and the light L3 travels straight from the core 9A of the light emitting side optical waveguide 9 through the coordinate input region 11 to the core 3A of the light receiving side waveguide 3. It enters and is detected via the light receiving element 2.
The optical touch panel 7 configured as described above detects the blocking signal by the light receiving element 2 when the light L3 crossing the coordinate input area 11 is blocked by a finger, a pen, or the like. Can be recognized.

[Example]
A photosensitive liquid resin containing an epoxy ultraviolet curable resin having an alicyclic skeleton (EP4080E manufactured by Adeka Corp.) is applied to the surface of a polyethylene nephthalate film having a thickness of 188 μm, and irradiated with ultraviolet rays of 1000 mJ / cm ² , followed by And an under cladding layer (refractive index at a wavelength of 830 nm = 1.510) having a thickness of 20 μm was formed.

A photosensitive liquid resin containing an epoxy-based ultraviolet curable resin containing fluorene skeleton (Ogsol EG manufactured by Osaka Gas Chemical Co., Ltd.) is applied to the surface of the under clad layer, and a core layer is formed by heat treatment at 100 ° C. for 5 minutes. After that, the core layer was covered with a photomask (gap 100 μm), irradiated with ultraviolet rays 2500 mJ / cm ² , and further heat-treated at 100 ° C. for 10 minutes. The core layer irradiated with ultraviolet rays is dissolved and removed by γ-butyrolactone aqueous solution, and the heat treatment is performed at 120 ° C. for 5 minutes to form a patterned core (refractive index at a wavelength of 830 nm = 1.593). Formed.

Next, a quartz concave mold was disposed so as to cover the entire core, and the mold was filled with the same photosensitive liquid resin as the undercladding layer. From the surface of the mold, ultraviolet rays are irradiated at 2000 mJ / cm ² , heat treatment is performed at 80 ° C. for 5 minutes, and the mold is peeled off. An overcladding layer (refractive index at a wavelength of 830 nm = 1.510) having a thickness of 1 mm (with a curvature radius = 1.5 mm) was molded to produce an optical waveguide.

  This optical waveguide is bonded onto a transparent panel made of an acrylic resin using an adhesive layer containing epoxy adhesive and activated carbon (absorbing light of a wavelength in the range of 450 nm to 700 nm 80% or more), and further A CMOS linear sensor array (manufactured by TAOS) was coupled as a light receiving element to the end of the core of the optical waveguide to produce a light receiving panel.

[Comparative example]
A light receiving panel was produced in the same manner as in Example, except that an epoxy adhesive not containing activated carbon was used as an adhesive for bonding the optical waveguide and the transparent panel.

[Evaluation]
An optical waveguide with a light emitting element (VCwell made by Optwell (emitting light with a wavelength of 850 nm)) is disposed at a position facing the light receiving side optical waveguide coupled to the light receiving element in the light receiving panel manufactured in the example and the comparative example. 2. An optical touch panel 7 shown in FIG. 3 was produced.

In general, when the optical touch panel is used outdoors, if the coordinate input area is not touched with a pen or the like, the light emitted from the light emitting element travels straight through the coordinate input area from each core of the light emitting side optical waveguide. The light enters the core of the light receiving side optical waveguide. At this time, natural light also enters from each core of the light receiving side optical waveguide. The light intensity detected through the light receiving element in this state is at a high level L as shown in FIG.
When the coordinate input area is touched with a pen or the like, near infrared light emitted from the light emitting element is blocked by the pen or the like, but an optical touch panel is used outdoors, and natural light is incident on the light receiving element. Then, the light intensity representing the blocking signal detected through the light receiving element is as shown in S1 in FIG. 4, and the light intensity does not decrease so much due to disturbance due to light in the visible light region.
On the other hand, when the disturbance due to the light in the visible light region is effectively eliminated as in the optical touch panel 7 manufactured using the light receiving panel 1 according to the above-described embodiment, the light receiving element 2 is used. The light intensity representing the detected blocking signal is as shown in S2 in FIG. 4, and is greatly reduced because there is almost no disturbance due to light in the visible light region. In this respect, it can be said that the optical touch panel is excellent in sensitivity with less disturbance due to light in the visible light region as the light intensity representing the blocking signal is reduced.

  When the optical touch panel provided with the light receiving panel of the example and the comparative example was used in an indoor window of 5400 lux and the light intensity of the blocking signal was measured, the optical touch panel according to the example was 0.3, It was 0.6 in the optical touch panel according to the specific soft example. Thus, the value of the light intensity obtained by the optical touch panel of the example is ½ of the cutoff signal obtained by the optical touch panel of the comparative example. It was confirmed that the sensitivity was much better than that.

[Measurement methods used in Examples and Comparative Examples]
(1) Refractive Index Measurement A clad layer forming varnish and a core forming varnish are each formed on a silicon wafer by spin coating to prepare a refractive index measuring sample, and a prism coupler (product name “SPA” manufactured by Cylon Co., Ltd.) is prepared. -400 ").
(2) Measurement of core width and height The cross section of the produced optical waveguide was cut using a Tyser type cutting machine (product name “DAD522” manufactured by DISCO), and the cut surface was cut by a laser microscope (manufactured by KEYENCE). Was observed and measured.

  According to the present invention, it is possible to provide a light receiving panel that eliminates the influence of disturbance light components caused by natural light and does not malfunction even when used under natural light, and an optical touch panel using the light receiving panel, It is very useful for industry.

DESCRIPTION OF SYMBOLS 1 Light reception panel 2 Light receiving element 3 Learning side waveguide 3A Core 3B Upper clad layer 3C Lower clad layer 4 Transparent panel 5 Adhesive layer 6 Resin layer 7 Optical touch panel 8 Adhesive layer 9 Light emission side waveguide 9A Core 9B Upper clad Layer 9C Lower clad layer 10 Light emitting device

Claims (2)

A light receiving element that receives light from the visible light region to the near infrared region;
An optical waveguide coupled to the light receiving element;
A transparent panel disposed below the optical waveguide;
A light receiving panel comprising an adhesive layer for bonding the optical waveguide and the transparent panel,
The light-receiving panel, wherein the adhesive layer absorbs 70% or more of light in a wavelength range of 450 nm to 700 nm. A light emitting device that emits light in the near infrared region;
A light emitting side optical waveguide coupled to the light emitting element;
A transparent panel to which the light emitting side optical waveguide is fixed;
A light receiving element that receives light from the visible light region to the near infrared region;
A light receiving side waveguide that is bonded to the transparent panel through an adhesive layer facing the light emitting side optical waveguide, and is coupled to the light receiving element;
The optical touch panel, wherein the adhesive layer that adheres the light-receiving side waveguide to the transparent panel absorbs light in a wavelength range of 450 nm to 700 nm by 70% or more.

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