JP2013083840A - Input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device capable of uniformly distributing light from a light source to two sides of a frame-shaped optical waveguide without requiring high accuracy in alignment between the light source and an optical waveguide core.SOLUTION: An optical waveguide core 1 on the light emission side in a frame-shaped optical waveguide 10 arranged around a rectangular detection space S of an input device is formed of a common part 1a on the light incident side contacting a light emitting element 3 provided in a corner 10a, a first core part 1b linearly extended from the common part 1a in one side direction of the frame along the light emitting optical axis of the light emitting element 3, and a second core part 1c having a light emission side curved with a predetermined curvature from a branch point J of the common part 1a and extended therefrom in the other side direction of the frame orthogonal to the optical axis. In the branch point J of the optical waveguide core 1 on the light emission side, a ratio of a core width (W2) of the second core part 1c to a core width (W1) of the first core part 1b is one or more [(W2/W1)≥1].

Description

  The present invention relates to an input device that detects the position of an input body such as a finger or a pen by shielding a light grating formed inside a frame-shaped optical waveguide.

  2. Description of the Related Art Conventionally, an input device that optically detects the position of a finger, a pen, or the like using an optical waveguide has been used as a means (input interface) for inputting instructions, coordinate information, and the like to a computer and various devices (Patent Literature). 1 and 2).

  FIG. 5 is a diagram showing a configuration of a conventional input device using an optical waveguide. Reference numeral 20 in the figure denotes a frame-shaped optical waveguide (including a clad layer) that also serves as a frame of the input device, and a detection space S for detecting an input body is provided in the space inside the optical waveguide. Is formed. In the drawing, the light-emitting side optical waveguide core 11 for emitting light to the detection space S is indicated by a dotted line, and the light-receiving side optical waveguide core 12 is indicated by a two-dot chain line.

  As shown in FIG. 5, this optical waveguide type input device includes a rectangular frame-shaped optical waveguide 20 having a width and optical elements (light-emitting element 13 and light-receiving element) attached to the outer edge of the frame-shaped optical waveguide 20. 14), and light emission of the light emitting side optical waveguide core 11 connected to the light emitting element 13 on the inner edges of the two sides (in this example, the upper side 20X and the right side 20Y) of the frame-shaped optical waveguide 20 A side end (light-emitting portion 11a) is disposed. Further, the light emitted from the light emitting element 13 passes through the light emitting portion 11a of the light emitting side optical waveguide core 11 as a large number of substantially parallel lights, which are opposed to the respective sides 20X and 20Y (in this example, the side 20X ′ and the side 20Y ′), the light is emitted (projected), and a light grating is formed in a space (detection space S) surrounded by the frame. Then, the lattice-shaped light is incident on the light receiving side optical waveguide core 12 on the opposite inner edge of the frame-shaped optical waveguide 20 corresponding to each light output portion 11a (light receiving portion 12a). ) Is guided to the light receiving element 14 connected thereto.

  The light-emitting side optical waveguide core 11 in the frame-shaped optical waveguide 20 is used for emitting a plurality of lights toward the one side 20X side of the frame immediately after the light incident side end (start end 11d) where the light from the light emitting element 13 enters. .., And a plurality of light emitting cores 11c, 11c,... Facing toward the other side 20Y. The light is distributed to a large number of light emitting cores 11b and 11c, and is emitted from the light emitting side terminal portion (light emitting portion 11a) of each core positioned at the inner edge of the frame.

  In the input device having the above-described configuration, when an object (input body) such as a finger shields a part of the grating of light passing through the detection space S, the shielded portion becomes the light-receiving side optical waveguide core. The light receiving element 14 connected to 12 senses a decrease in the amount of light and specifies the position of the part touched by the finger or the like (for example, the xy coordinates in the detection space S).

JP-T-2001-51479 JP 2010-20103 A

  By the way, according to the inventor's research, in an input device using a frame-shaped optical waveguide as described above, it is difficult to evenly distribute light from a light source (light emitting element) to two adjacent sides in the frame. It turns out that there are many cases. For example, in FIG. 5, light incident on the light-emitting side optical waveguide core 11 from the light-emitting element 13 transmits light to one side (side 20Y) along the light emission optical axis of the light-emitting element 13. In the light emitting core 11b that transmits light to the other side (side 20X) extending in the direction orthogonal to the optical axis, the light travels in a largely curved manner from the starting end portion 11d of the core. It will be. For this reason, the light loss at the curved portion is increased, and as a result, it has been found that the amount of light distributed to the two sides (side 20X side and side 20Y side) orthogonal to each other is not easily equalized.

  Further, the optical waveguide 20 used in this conventional input device has a multi-branched core in which the light-emitting side optical waveguide core 11 is uniquely designed for each of the one side 20X side and the other side 20Y side. Therefore, alignment between the core 11 and the light source is difficult. The inventor supposes that if the optical axis of the start end portion 11d of each of the light emitting cores 11b and 11c is deviated from the optical axis of the light emitting element 13, there is a difference in the amount of light distributed between the side 20X side and the side 20Y side. And found out that it would be bigger. There is room for improvement here.

  The present invention has been made in view of such circumstances, and the alignment between the light source and the optical waveguide core does not require high accuracy, and the light from the light source is evenly distributed on the two sides of the frame-shaped optical waveguide. It is an object of the present invention to provide an input device that can be distributed among the devices.

  In order to achieve the above object, an input device according to the present invention includes a frame-shaped optical waveguide disposed around a rectangular detection space, and a light-emitting element disposed on a rectangular outer edge of the frame-shaped optical waveguide. And detecting light shielding from the light emitting side end of the light emitting side optical waveguide core positioned at the inner edge of the frame-shaped optical waveguide to the light incident side end of the corresponding light receiving side optical waveguide core An input device for acquiring position information of an input body located in the detection space, wherein the light emitting element is arranged in a predetermined direction on an outer edge of one corner of the frame-shaped optical waveguide, A bifurcated light-emitting side optical waveguide core that distributes light emitted from the light emitting element at a predetermined ratio in the two side directions orthogonal to each other is provided on two sides of the frame adjacent to the corner portion. The branched light-emitting side optical waveguide core is A common portion on the light incident side provided at a corner portion in contact with the element, and a first core portion extending linearly in one side direction of the frame along the optical axis of light emission of the light emitting element, continuous to the common portion. A branch of the light-emitting side optical waveguide core, which is formed from a second core portion which is curved with a predetermined curvature from the branch point of the common portion and whose light emission side extends in the direction of the other side of the frame perpendicular to the optical axis. The ratio of the core width (W2) of the curved second core portion to the core width (W1) of the linear first core portion at a point becomes 1 or more [(W2 / W1) ≧ 1]. It takes the composition that it is.

  That is, in order to solve the above problems, the inventor of the present invention has repeatedly researched on the optical path of a frame-shaped optical waveguide, and branched optical waveguides directed in two directions orthogonal to the direction along the optical axis of the light source. The starting end side of the core is integrated into a wide common portion, and light from the light source is received at the end of the wide common portion (light incident side) and curved from the common portion to extend in the other side direction. By making the width of the optical waveguide core (second core portion) on the side wider than the width of the linear optical waveguide core (first core portion) along the optical axis, Found that the amount of can be equalized. In addition, the inventor can simultaneously adjust the balance of the amount of light distributed in the two directions without being greatly affected by the alignment accuracy when the light-incidence common portion having the wide width is made to correspond to the light source. The headline, the present invention has been reached.

  As described above, in the input device according to the present invention, the common part of the bifurcated light-emitting side optical waveguide core is arranged at the corner that is in contact with the light source (light-emitting element), and the bifurcated core is the common part. A first core portion extending in one side direction of the frame along the light emission optical axis of the light emitting element, and the other side of the frame that is curved with a predetermined curvature and whose light emission side is orthogonal to the optical axis. And the ratio of the core width (W2) of the second core portion to the core width (W1) of the first core portion at this branching point is 1. It is formed so that [(W2 / W1) ≧ 1].

  Thus, the input device allows for the core width of the second core portion at the branch point in consideration of the optical loss at the curved portion of the second core portion extending in the direction orthogonal to the optical axis of the light emitting element. It is wider (thicker) than the core part of 1 so that more light is distributed. Therefore, the difference in the amount of light reaching the second core portion after passing through the curved portion and becoming linear and the first core portion continuing linearly from the common portion is reduced, The amount of light distributed to these two orthogonal sides is equalized.

  Furthermore, in the input device of the present invention, the light incident side start end portions of the bifurcated light emitting side optical waveguide core are integrated as one common portion, and this common portion is made to correspond to the light source. Therefore, unlike an input device using a conventional optical waveguide, high-precision alignment between the optical waveguide core and the light source is not required. For example, even if the optical waveguide core and the light source are not precisely aligned, the total amount of light propagating through the optical waveguide core is reduced, and the amount of light distributed to the two orthogonal sides is biased. Will not occur.

  In the input device of the present invention, the curved portion of the second core portion of the bifurcated light-emitting side optical waveguide core has a ¼ circular shape, and the radius of curvature (R) thereof is If the core width (W2) of the core part 2 is 15 times or more [R ≧ (15 × W2)], the optical loss due to the curvature of the core can be further reduced. As a result, this input device is easy to adjust the light quantity balance between the second core portion having the curved portion and the linear first core portion, and the light distributed to these two orthogonal sides is Can be distributed in ideal conditions.

  Further, among the input devices of the present invention, the other two sides respectively facing the two sides of the frame where the bifurcated light-emitting side optical waveguide core is disposed are connected to the light emitting sides of the light-emitting side optical waveguide core. Corresponding to the end portion, a light receiving side optical waveguide core that is guided by the light from the light emitting side optical waveguide core and guided to the light receiving element is provided in the detection space for detecting an input body. A grid of light intersecting the frame in the vertical and horizontal directions is formed, and it is possible to detect a highly accurate input body without a blind spot in this detection space.

(A) is a top view which shows the structure of the input device of this invention, (b) is the P section enlarged view. (A)-(e) is a figure explaining the method of producing the frame-shaped optical waveguide used for the input device of this invention. It is a graph showing the relationship between the core width (W2) and bending loss (dB) of the optical waveguide in the input device of the present invention. It is a graph showing the relationship between the ratio (R / W2) of the curvature radius R to the core width W2 of the optical waveguide and the bending loss (dB) in the input device of the present invention. It is a figure which shows the structure of the conventional input device using an optical waveguide.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  A frame-shaped optical waveguide input device whose whole image is shown in FIG. 1A is placed on, for example, a liquid crystal screen (flat panel display) as a display device, and the center of the frame-shaped optical waveguide 10. The position of an input body such as a finger or a pen located in a detection space (detection region) S formed in the section is acquired as coordinates (xy coordinates) in the detection space S, and the position information is obtained by a computer. And output to information equipment such as ATM.

  The frame-shaped optical waveguide 10 includes a clad layer 5 formed in a rectangular shape that is horizontally long (length of long side 10X: length of short side 10Y = 16: 9) in accordance with the size of the screen of the display. The light emitting element 3 as a light source is attached to the outer edge of one corner 10a in a predetermined direction. The core (1, 2) is an optical path formed so as to be buried in the clad layer 5. It has been.

  The frame-shaped optical waveguide 10 receives light emitted from the light-emitting element 3 on two sides (long side 10X and short side 10Y in the figure) adjacent to the corner 10a of the cladding layer 5. , A light emitting side optical waveguide core 1 (dotted line) that distributes in a predetermined ratio in the two sides (10X, 10Y) directions orthogonal to each other is provided, and the other two sides (10X ′, 10Y, 10Y ') is provided with a plurality of light receiving side optical waveguide cores 2 (two-dot chain lines) for allowing the light from the light emitting side optical waveguide core 1 to enter and guide the light to the light receiving elements (light receiving element array 4).

  Further, as shown in the enlarged view of FIG. 1B, the light emitting side optical waveguide core 1 includes a light incident side common portion 1a disposed at a corner portion 10a of the frame-shaped optical waveguide 10, and a common portion 1a. The first core portion 1b extending in the direction of one side (10X) along the optical axis (one-dot chain line) of light emission of the light-emitting element 3 and a curve with a predetermined radius of curvature R from the branch point J of the common portion 1a. In addition, the light emitting side is formed from a second core portion 1c extending in the direction of the other side (10Y) perpendicular to the optical axis. The bifurcated light-emitting side optical waveguide core 1 has a core width W2 of the curved second core portion 1c at the branch point J, and a core width W1 of the linear first core portion 1b. It is formed so as to be wider [that is, (W2 / W1) ≧ 1]. This is a feature of the input device of the present invention.

  The above-mentioned input device will be described in more detail. For example, in the case of a polymer-based optical waveguide, the frame-shaped optical waveguide 10 used in this input device is a frame-shaped cladding layer 5 (overclad layer) formed using a resin material. 5a and the under cladding layer 5b), the light emitting side optical waveguide core 1 and the plurality of light receiving side optical waveguide cores 2 are formed by patterning in the above-described shape by a photolithography method or the like.

  The light-emitting side optical waveguide core 1 is configured to receive light incident on the light-emitting element 3 so that the light emitted from the light-emitting element 3 can be distributed at a predetermined ratio in the two sides (10X, 10Y) directions orthogonal to each other. Branches from the end portion (common portion 1a) of the frame in two directions: a first core portion 1b in the x direction (long side 10X side) and a second core portion 1c in the y direction (short side 10Y side). The tip (light emitting part) of each light emitting path 1x, 1y on the light emitting side is the inner edge of the frame-like clad layer 5 (in FIG. 1 (a), the upper edge and the right edge). ] At predetermined positions. Then, by emitting (projecting) the light from the light emitting element 3 from the tip of each of the light emission paths 1x and 1y, the light that intersects the vertical and horizontal (xy directions) of the frame in the detection space S inside the frame. A lattice (dotted lines and arrows indicate the traveling direction of light) is formed.

  As shown in FIG. 1B, the common portion 1a of the light emitting side optical waveguide core 1 is a core in which the first core portion 1b (width: W1) and the second core portion 1c (width: W2) are combined. It is formed in a wide shape corresponding to the width W0, and an end surface on one end side (right side in the drawing) is an optical coupling surface on which light (white arrow) from the light source (light emitting element 3) enters. Note that the core width W 0 of the common portion 1 a is usually wider than the light emitting portion width H of the light emitting element 3 in order to facilitate optical coupling with the light emitting element 3. For example, when the light emitting portion width H of the light emitting element 3 is about 10 μm, the core width W0 of the common portion 1a is designed to be 40 to 1000 μm. Moreover, it is preferable that the length L [length from the one end surface (optical connection surface) to the said branch point J] of the common part 1a in the optical axis (one-dot chain line) direction shall be 150-5000 micrometers.

  The first core portion 1b branched from the common portion 1a extends a part of the common portion 1a so that the light from the light emitting element 3 can pass straight after branching at the branch point J. As shown in FIG. As described above, the core width W1 is formed narrower (narrower) than the core width W2 of the second core portion 1c described later, and the width W1 is preferably about 20 to 500 μm, more preferably It is about 40 to 300 μm.

  The second core portion 1c branched from the first core portion 1b at the branch point J is curved into a quarter circle (arch shape) immediately after the branch point J as shown in FIG. Then, the tip end side is formed in a shape extending linearly toward the short side 10Y side of the frame. The curved portion of the second core portion 1c bends the light (optical axis) of the light emitting element 3 projected along the long side 10X direction of the frame by 90 ° in the short side 10Y direction. In order to prevent an increase in optical loss, the radius of curvature R of the curved portion is 15 times or more [R ≧ (15 × W2)] the core width W2 of the second core portion 1c.

  Note that, as described above, the branch width J and the core width W2 after the branch are formed wider (thicker) than the core width W1 of the first core portion 1b, preferably 20 to 500 μm, more preferably. Is 40-300 μm. Further, the ratio (W2 / W1) of the core width W1 of the first core portion 1b and the core width W2 of the second core portion 1c at the branch point J is preferably 1 to 5, more preferably. Is 1-4. Furthermore, although the suitable thickness (height) of the said optical waveguide core 1 is based also on the size of the light emission part of the light emitting element 3 mentioned later, it is about 20-100 micrometers, for example.

  In addition, in order to avoid complicated illustration, each of the light emission paths 1x and 1y in FIG. 1A shows only a part of the many light emission paths 1x and 1y with a solid line, and the rest with a dotted line. (The same applies to the emitted light-dotted arrow). The number of the light emission paths 1x and 1y is appropriately designed according to the size and resolution of the input device. For example, the number of the light emission paths 1x on the long side 10X branching from the first core portion 1b is used. Is about 200 to 800, and the number of light exit paths 1y on the short side 10Y branching from the second core portion 1c is about 100 to 600.

  On the other hand, on the sides (long side 10X ′, short side 10Y ′) facing the light emitting side optical waveguide core 1 with the detection space S interposed therebetween, the tips (light emitting portions) of the light emitting paths 1x and 1y are provided. A plurality of light receiving side optical waveguide cores 2 corresponding to each of the above are formed. The end portions (light receiving portions) on the light incident side of the respective light receiving side optical waveguide cores 2 are inner edges of the frame facing each front end (light emitting portion) of the light emitting side core 1 [the lower side edge in FIG. And the left side edge] are respectively positioned at predetermined positions, and light that has passed through the detection space S and entered the tip (light receiving portion) of each light receiving side optical waveguide core 2 passes through the light incident paths 2x and 2y. These are guided to a light receiving element array 4 having a large number of light receiving elements corresponding to each of the tips.

  For the light source (light emitting element 3) used in the input device, a light emitting diode (LED), a semiconductor laser, or the like is used. Among them, a VCSEL (vertical cavity surface emitting laser) excellent in light transmission is preferably used. . The wavelength of the light emitted from the light emitting element 3 is preferably near infrared (wavelength: 700 to 2500 nm).

  Further, as shown in FIG. 1A, the light emitting element 3 is disposed at a corner 10a on the short side 10Y side of the frame-shaped optical waveguide 10, and the light emitting portion (width H) is in the direction of the long side 10X of the frame. It is positioned so as to face. With this arrangement, the light emitted from the light emitting element 3 is incident on the end surface (optical coupling surface) of the common portion 1a of the light emitting side optical waveguide core 1 as shown in FIG. Reach the 10X end without turning. Therefore, this input device can efficiently use the light from the light emitting element 3.

  As the light receiving element array 4, an image sensor such as a CCD or CMOS, a CMOS linear sensor array in which a large number of light receiving elements are arranged in a row, or the like can be used.

  In the input device having the above-described configuration, as described above, the light-emitting side optical waveguide core 1 is branched / curved from the first core portion 1b extending linearly toward the long side 10X of the frame and the branch point J. Then, the second core portion is formed in a pattern branched to the second core portion 1c extending to the short side 10Y side of the frame, and considering the “light loss due to bending” of the second core portion 1c. The core width W2 of 1c is wider than the core width W1 of the first core portion 1b (W1 ≦ W2), and the width ratio (W2 / W1) is 1 or more. Therefore, in this input device, the light incident on the common portion 1a is distributed to two sides (long side X side and short side Y side) of the frame orthogonal to each other in a balanced state with a small difference in light amount. .

  When the ratio (W2 / W1) of the core width W2 of the second core portion 1c to the core width W1 of the first core portion 1b is less than 1, the long side 10X side extending linearly from the common portion 1a There is a tendency that the amount of light of one core portion 1b becomes too strong. On the contrary, when the ratio of the core width (W2 / W1) exceeds 5, the light amount of the second core portion 1c on the short side 10Y side that curves and branches from the common portion 1a becomes too strong, and the light amount balance. Tend to be worse.

  In addition, since the first core portion 1b on the long side 10X side and the second core portion 1c on the short side 10Y side are branched from the common portion 1a corresponding to the light emitting element 3, the common portion Even if the alignment between the light emitting element 1a and the light emitting element 3 is slightly shifted, the light amount difference between the long side 10X side and the short side 10Y side due to this shift is alleviated, and the light amount balance between these lights is maintained. It is. Therefore, this input device has a wider allowable range of alignment between the light emitting element 3 and the light emitting side optical waveguide core 1 than an input device having a conventional configuration.

  Furthermore, in the input device having the above configuration, the curvature radius R of the curved portion of the second core portion 1c that is curved is 15 times or more the core width W2 of the second core portion 1c [R ≧ (15 × W2 )], It is possible to reduce the light loss of the curved portion. For example, when the core width W2 of the second core portion 1c is 20 to 500 μm as described above, the light loss (bending loss) due to the bending can be suppressed to about 3 dB or less (this point is described in “ This will be described in “Examples”).

  The light emitting side end of the light emitting side optical waveguide core 1 (light emitting part at the tip of each light emitting path 1x, 1y of the core 1) and the light incident side end of each light receiving side optical waveguide core 2 (core 2). It is desirable that the light receiving portion is in the shape of a lens (arc-shaped in plan view) that warps toward the inside of the frame. By making the light emission side end portions of the light emitting side optical waveguide core 1 into the lens shape, light rays perpendicular to the inner edge of the frame-shaped optical waveguide 10 and parallel to each other can be emitted from these light emission side end portions. it can. Further, by making the light incident side end portions of the respective light receiving side optical waveguide cores 2 into the lens shape, the light collection efficiency of these light incident side end portions can be increased. When the light emitting part and the light receiving part of each of the cores 1 and 2 are not formed in a lens shape, a separate lens body is prepared and installed along the periphery in the detection space S of the frame-shaped optical waveguide 10. Also good.

  Moreover, in the said embodiment, although the branched light emission side optical waveguide core 1 of the optical waveguide demonstrated as an example the polymer type | system | group optical waveguide formed using the resin material (polymer material), this core 1 is comprised. The material to be used may be a material having a refractive index higher than that of the cladding layer 5 disposed around, for example, glass. However, the difference in refractive index between the core 1 and the surrounding clad layer 5 is preferably 0.01 or more. In consideration of the patterning property of the above shape, a photosensitive resin such as an ultraviolet curable resin is the most. preferable. Examples of the ultraviolet curable resin to be used include acrylic, epoxy, siloxane, norbornene, and polyimide.

  Further, the cladding layer 5 around the core 1 may be made of a material having a lower refractive index than the core 1 among the photosensitive resins such as the ultraviolet curable resin. In addition, the clad layer 5 can be made of a material that also serves as a flat substrate, such as glass, silicon, metal, and resin. Furthermore, the cladding layer 5 may be only the under cladding layer (5b described later) on the lower side of the core 1, and the over cladding layer (5a described later) covering the core 1 may not be formed. The frame-shaped optical waveguide 10 can be manufactured by a dry etching method using plasma, a transfer method, a photolithography method using exposure / development, a photo bleach method, or the like.

Next, an example of a method for manufacturing the input device will be described.
2A to 2E are cross-sectional views schematically illustrating a method for manufacturing an optical waveguide for an input device according to an embodiment of the present invention. In FIG. 2, only the light emitting side of the optical waveguide is shown, and the light receiving side produced in parallel with this is not shown. Further, reference numeral 1 in the figure denotes a core (light-emitting side optical waveguide core), 5b is an under cladding layer, 5a is an over cladding layer, 21 is a base, 22 is a molding die, and FIGS. e) represents the process sequence in which the optical waveguide is fabricated.

  First, a base 21 for forming a frame-shaped optical waveguide is prepared and placed on a flat place. As the material of the base 21, a material capable of peeling the polymer optical waveguide to be manufactured later is selected.

  Next, as shown in FIG. 2A, an under cladding layer 5 b is formed on the surface of the base 21. The under cladding layer 5b can be formed by photolithography using a photosensitive resin as a forming material. The thickness of the under cladding layer 5b is set within a range of 5 to 50 μm, for example.

  Next, as shown in FIG. 2B, a patterned light-emitting side optical waveguide core 1 and light-receiving side optical waveguide core (not shown) are formed on the surface of the under cladding layer 5b by photolithography. . As a material for forming these cores 1 (and 2), a photosensitive resin having a refractive index higher than that of the material for forming the under cladding layer 5b and the over cladding layer 5a described later is used. As described above, the inner edges of the frame of the light emitting side optical waveguide core 1 and the light receiving side optical waveguide core [the light emitting portions at the tips of the light emitting paths 1x and 1y of the core 1 and the light receiving side optical waveguide cores 2] The light receiving part at the front end of the light incident side: see FIG. 1A] is formed in a lens shape in plan view.

  Next, a mold 22 having translucency for forming the over clad layer 5a is prepared. As shown in FIG. 2 (c), the molding die 22 is formed with a recess (molding cavity) having a mold surface corresponding to the surface shape of the over cladding layer 5a. A portion covering the distal end side ends of the emission paths 1x and 1y (a right end portion in FIG. 2C) is formed in a circular arc lens curved surface having a quarter circle in the vertical direction (thickness direction of the optical waveguide). I am using something.

  Next, the molding die 22 is placed with the concave portion facing up (with the top and bottom reversed), and the molding die 22 is placed on a molding stage (not shown). First, the overcladding layer 5a is formed in the concave portion. The photosensitive resin (varnish shape) is filled. Next, the core 1 formed on the undercladding layer 5b is positioned with respect to the concave portion of the mold 22, and in this state, the undercladding layer 5b is pressed against the mold 22 and the varnish-like overcladding is performed. The core 1 is immersed in the photosensitive resin for forming the layer 5a. In this state, the photosensitive resin is irradiated with ultraviolet rays or the like through the mold 22 to expose the photosensitive resin. As a result, the photosensitive resin is cured to form an over clad layer 5a in which a portion corresponding to the inner edge side tip of the core 1 (and 2) is formed in a lens shape as shown in FIG. 2 (d). Is done.

  Next, after the curing of the photosensitive resin is completed, the over clad layer 5a is removed from the mold 22 together with the core 1, the under clad layer 5b and the base 21, and the base 21 is peeled off and removed. As a result, a frame-shaped optical waveguide 10 as shown in FIG.

  Next, as shown in FIG. 1A, the light emitting element 3 faces the end surface (optical coupling surface) of the common portion 1 a of the core 1 at a predetermined position of the corner portion 10 a of the obtained frame-shaped optical waveguide 10. Are arranged, and the optical axis of the common portion 1a and the optical axis of the light emitting element 3 are aligned and positioned. Moreover, the input device in this embodiment can be manufactured by attaching the light receiving element array 4 to the light receiving side and connecting wirings not shown.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

  In the present embodiment, the “ratio of the core width W2 of the second core portion to the core width W1 of the first core portion (W2 / W1)” of the light emitting side optical waveguide core 1 [see FIG. 1B] An optical waveguide with various modifications is manufactured, and a light emitting element is connected to the optical waveguide to form an input device. Using the input devices of Examples 1 to 4 and Comparative Example 1, the long side 10X side and the short side The amount of light emitted from the 10Y side (light intensity) was measured with a light receiving element, and the light amount difference (balance) between the long side 10X and the short side 10Y was compared.

First, an optical waveguide forming material was prepared.
[Formation material of under cladding layer]
Component A: 75 parts by weight of an epoxy resin containing an alicyclic skeleton (manufactured by Daicel Chemical Industries, EHPE 3150) Component B: 25 parts by weight of an epoxy group-containing acrylic polymer (manufactured by NOF Corporation, Marproof G-0150M) Component C: light 4 parts by weight of an acid generator (manufactured by San Apro, CPI-200K) These components A to C are dissolved in cyclohexanone (solvent) together with 5 parts by weight of an ultraviolet absorber (manufactured by Ciba Japan, TINUVIN479), thereby undercladding. A layer forming material was prepared.

[Core forming material]
Component D: 85 parts by weight of epoxy resin containing bisphenol A skeleton (manufactured by Japan Epoxy Resin, 157S70) Component E: 5 parts by weight of epoxy resin containing bisphenol A skeleton (manufactured by Japan Epoxy Resin, Epicoat 828) Component F: Epoxy group Containing styrene-based polymer (manufactured by NOF Corporation, Marproof G-0250SP) 10 parts by weight These components D to F and 4 parts by weight of the above component C were dissolved in ethyl lactate to prepare a core forming material.

[Formation material of over clad layer]
Component G: 100 parts by weight of an epoxy resin having an alicyclic skeleton (manufactured by ADEKA, EP4080E) By mixing this component G and 2 parts by weight of the above component C, a material for forming an overcladding layer was prepared.

[Example 1]
<Fabrication of optical waveguide>
[Formation of underclad layer]
First, the under clad layer forming material was applied to the surface of a stainless steel base (flat plate), and then a drying process was performed at 160 ° C. for 2 minutes to form a photosensitive resin layer. Next, the photosensitive resin layer was exposed to ultraviolet rays to be exposed to an integrated light quantity of 1000 mJ / cm ² to form an under cladding layer having a thickness of 20 μm [see FIG. 2 (a)].

[Formation of core]
Next, after the core forming material was applied to the surface of the under cladding layer, a heat treatment was performed at 170 ° C. for 3 minutes to volatilize the solvent to form a photosensitive resin layer for core formation. Next, ultraviolet rays are irradiated (gap 100 μm) through a photomask in which an opening pattern having the same shape as the branched core pattern is formed, and exposure with an integrated light quantity of 3000 mJ / cm ² is performed, and then 120 ° C. × 10 Heat treatment for minutes was performed to complete the resin curing. Then, by performing dip development using a developer (γ-butyrolactone), the unexposed portion is dissolved and removed, and then subjected to a heat drying treatment at 120 ° C. for 5 minutes, whereby a patterned thickness (height) is obtained. A 50 μm branched core was formed.

  In the first embodiment, the opening width (W1) corresponding to the first core portion at the core branching point is 180 μm, the opening width (W2) corresponding to the second core portion is 180 μm, and these common portions are joined together. A photomask having an opening pattern with an opening width (W 0) corresponding to 1 is 360 μm (see FIG. 1B). Therefore, each part of the core is also formed along this, and the core width W1 of the first core part is 180 μm, and the core width W2 of the second core part is 180 μm. In addition, the ratio (W2 / W1) of the core width W2 of the second core portion to the core width W1 of the first core portion is “1” (the lower limit of the preferred range). Note that the opening width corresponding to the first and second core portions in the opening pattern of the photomask is changed in Examples 2, 3, and 4 and Comparative Example 1 described later.

  In addition, the photomask has 220 openings corresponding to the exit path on the long side 10X side (the light exit section at the front end of each exit path is in the shape of a lens in plan view) in a portion corresponding to the first core section after branching. In a portion corresponding to the second core portion after the branch is formed with 165 patterns corresponding to the exit path on the short side 10Y side (the light exit portion at the tip of each exit path is a lens in plan view). An opening pattern is formed, and simultaneously with the formation of the branched core, these emission paths are also formed (the position of the emission path in the opening pattern of the photomask is described in Example 2 described later). 3 and Comparative Examples 1 and 2).

[Formation of overclad layer]
Next, a mold having translucency for forming an overcladding layer was prepared. This mold includes a molding cavity corresponding to the surface shape of the overcladding layer. Then, with the concave portion facing upward, the mold was placed on the molding stage, and the concave portion was filled with the material for forming the over clad layer.

Next, a core patterned on the surface of the under cladding layer is positioned with respect to the concave portion of the mold, and in this state, the under cladding layer is pressed against the mold to form a material for forming the over cladding layer ( The core was immersed in a varnish form. Then, in this state, ultraviolet rays are irradiated through the mold to the over clad layer forming material to perform exposure with an accumulated light amount of 8000 mJ / cm ² , and a portion of the over clad layer corresponding to the tip of the core However, an over clad layer formed on a lens curved surface (curvature radius of 1.5 mm) having a substantially 1/4 arc shape in the vertical direction was formed.

  Next, the over-cladding layer is demolded together with the under-cladding layer and the core from the mold, and the base is peeled off from the under-cladding layer. A thickness of 1 mm) was obtained.

<Production of input device for test>
[Attaching the light source]
At a predetermined position (see FIG. 1 (b)) that contacts the end portion (optical coupling surface) of the common portion of the light-emitting side optical waveguide core, located at the corner of the obtained frame-shaped optical waveguide, the light emission intensity (or Output) 3mW VCSEL light source (manufactured by Optowell) is arranged and aligned and aligned so that the center of the light emitting part (width H = 10μm) of the light source is on the extension of the optical axis of the core The lever light source was fixed, and the input device of Example 1 was produced.

[Attaching the light receiving element unit for measurement]
Next, a light receiving element unit (CMOS linear sensor array manufactured by Optiwell) for light intensity measurement is prepared, and light (signal) emitted from the tip (light emitting part) of each light emitting path of the light emitting side optical waveguide core is The light receiving element unit is positioned so as to individually enter each light receiving element of this sensor array (that is, one light receiving element corresponds to one light emission path), and in this state, the frame It was fixed to the optical waveguide with an adhesive or the like, and prepared so that the light intensity for each light emission path could be measured.

[Example 2]
In the formation of the optical waveguide in the [core formation], except that a photomask having a different ratio of the opening width corresponding to the first core portion and the opening width corresponding to the second core portion at the core branch point is used. In the same manner as in Example 1, the optical waveguide for manufacturing an input device of Example 2 in which the core width W1 of the first core part is 140 μm and the core width W2 of the second core part is 220 μm (core width ratio W2 / W1 = about 1.57). Then, the light source and the light receiving element unit for measurement were attached to the optical waveguide as described above to prepare an input device of Example 2, so that the light intensity for each light emission path could be measured.

[Example 3]
In the formation of the optical waveguide in the [core formation], except that a photomask having a different ratio of the opening width corresponding to the first core portion and the opening width corresponding to the second core portion at the core branch point is used. In the same manner as in Example 1, the optical waveguide for manufacturing an input device of Example 3 in which the core width W1 of the first core part is 120 μm and the core width W2 of the second core part is 140 μm (core width ratio W2 / W1 = 2) was produced. Then, the light source and the light receiving element unit for measurement were attached to the optical waveguide as described above to prepare an input device of Example 3, so that the light intensity for each light emission path could be measured.

[Example 4]
In the formation of the optical waveguide in the [core formation], except that a photomask having a different ratio of the opening width corresponding to the first core portion and the opening width corresponding to the second core portion at the core branch point is used. In the same manner as in Example 1, the optical waveguide for manufacturing an input device of Example 3 in which the core width W1 of the first core part is 80 μm and the core width W2 of the second core part is 280 μm (ratio of core width W2 / W1 = 3.5) was produced. Then, the light source and the light receiving element unit for measurement were attached to the optical waveguide as described above to prepare an input device of Example 4, so that the light intensity for each light emission path could be measured.

  As a comparative example, an optical waveguide in which the ratio (W2 / W1) of the core width W2 of the second core portion to the core width W1 of the first core portion deviates from the preferred range (1 to 5) of the present invention is manufactured. An input device was manufactured using this.

[Comparative Example 1]
In the production of the optical waveguide in [core formation], except that a photomask having a different ratio of the opening width corresponding to the first core portion and the opening width corresponding to the second core portion at the core branch point is used. In the same manner as in Example 1 above, the optical waveguide for manufacturing an input device of Comparative Example 1 in which the core width W1 of the first core part is 240 μm and the core width W2 of the second core part is 120 μm (core width ratio W2 / W1 = 0.5). Then, the light source and the light receiving element unit for measurement were attached to the optical waveguide as described above to prepare an input device of Comparative Example 1 so that the light intensity for each light emission path could be measured.

<Measurement and evaluation of light intensity>
Using the input devices of Examples 1 to 4 and Comparative Example 1 described above, each light source is caused to emit light and 850 nm infrared light is incident on the core, and the light intensity for each light emission path (emitted from the light emission path is The intensity of light reaching the light receiving element) was measured, and an average value I _X on the long side 10X side (220 lines) and an average value I _Y on the short side 10Y side (165 lines) were calculated. Then, the absolute value of the difference between the average values was obtained, and the difference between the light amounts distributed to the long side and the short side “light amount difference between the long side and the short side” was evaluated based on the magnitude of the absolute value.

  Note that the measurement was performed both in a state where the optical axis of the core and the optical axis of the light source matched (aligned) and in a state where they did not match. That is, in FIG. 1B, the center of the light source (light emitting element 3) is at a point O on the optical axis of the core 1, and the state where the optical axes coincide with each other is represented as “± 0 μm”. A state where the center is intentionally shifted by 100 μm to the A side (“y” direction) is displayed as “+100 μm”, and a state where the center of the light source is intentionally shifted by 100 μm is displayed as “−100 μm”.

  A laser microscope (manufactured by Keyence Corporation) was used to measure the core width and core height of the optical waveguide, and an optical microscope (MX51 manufactured by Olympus Corporation) was used to measure the deviation of the core center and light source.

  The measurement results are shown in “Table 1”.

  As shown in Table 1 above, in the input devices of Examples 1 to 4, the light amount difference between the long side 10X side and the short side 10Y side is 0.2 in the state “± 0 μm” in which the optical axes of the core and the light source coincide. It can be seen that the light from the light source can be distributed substantially evenly in two directions orthogonal to each other. In addition, even when the center of the light source is shifted to one side with respect to the optical axis of the core “+100 μm” and to the other side “−100 μm”, the difference in light amount between the long side and the short side is 1 at the maximum. .2 is small. From this, it can be seen that the input device of the present invention has a wide allowable range of alignment between the core and the light source.

  On the other hand, the input device of Comparative Example 1 has a large light amount difference of 2.0 on the long side 10X side and the short side 10Y side even when the optical axis of the core and the light source coincides with “± 0 μm”, and the center of the light source is In the states “+100 μm” and “−100 μm” shifted from the optical axis of the core, the light amount difference between the long side and the short side is further enlarged. Therefore, the input device of Comparative Example 1 is inferior in the above characteristics.

  Next, the result of verification performed on the relationship between the core width (W2) in the “curved part” of the bifurcated optical waveguide core of the input device of the present invention and the radius of curvature (R) of this “curved part” will be described. .

  In the present embodiment, a “second core portion of the light-emitting side optical waveguide core” (see the portion 1c in FIG. 1B) having one curved portion having a ¼ circular shape in plan view in the section is simulated. The optical waveguide core is manufactured, and the combination of the core width (W2) of the curved portion of the core and the curvature radius (R) of the curve is variously changed, and the light generated by the curvature (bend) of the core is changed. “Bending loss” (loss due to leaked light whose reflection angle exceeds the critical angle) was measured.

  The optical waveguide specimen used for the above measurement was manufactured by changing the pattern (opening shape) of the photomask at the time of core formation, using the same constituent materials and methods as in Example 1 above. The setting of the core width W2 is 15, 20, 30, 50, 75, 100, 150, 200, 250 μm, and the setting of the curvature radius R of the curved portion is 0.6, 0.8, 1.0, 1 5, 2.0, 2.5, and 3.0 mm. An optical waveguide (core) combining these set values was prepared and used as a test sample. The refractive index (850 nm) of each sample is 1.57 for the core, 1.51 for the over and under cladding layers, 50 μm in the core thickness (height), and the curvature radius R of the curved portion is The unit conversion (mm → μm) values are 600, 800, 1000, 1500, 2000, 2500, and 3000 μm, respectively.

The bending loss is measured by cutting the front and rear of the curved portion of the core of the test optical waveguide, and the optical loss between the front and rear cut portions (including one curved portion) [input optical power and output The difference in optical power] was performed according to the cut-back method of JIS C 6823 “Optical Fiber Loss Test Method”. The optical loss (bending loss) between two points (between two cross sections) sandwiching the “curved part” in the core is calculated by the following equation (1).
Bending loss (dB) = − 10 × log (Po / Pi) (1)
In the above equation, Pi is the input optical power at the core entrance end face, and Po is the output optical power at the core exit end face. Further, FieldMax II-TO manufactured by COHERENT was used for the measurement of optical power, and VCSEL PH85-F1P0S2 manufactured by Optiwell was used for the light source.

The measurement results of the “bending loss” are shown in FIGS.
FIG. 3 is a graph obtained by plotting the relationship between the core width (W2) of the optical waveguide and the bending loss (dB) obtained from the above measurement for each curvature radius (R) of the curved portion. FIG. 4 summarizes the results of FIG. 3 in the ratio (R / W2) of the radius of curvature (R: μm) to the core width (W2: μm). It is a graph showing the relationship between “R ratio (R / W2)” and the above “bending loss”. Note that “3 (dB)” used as the reference line in the graph shows that the intensity of the output light power (Po) after being curved with respect to the input light power (Pi) is 50% (the light power is halved). It corresponds to the point.

  According to the graph of FIG. 3, the “bending loss” (dB) of the core tends to be lower as the core width W2 is wider (thick) and lower as the curvature radius R of the curved portion is larger (slower). You can see that Looking at the bending loss of 3 dB as a reference (a 50% reduction in the amount of light), when the core width W2 is 50 μm and the radius of curvature R is 0.8 mm (R / W2 = 16), it is 2.98 dB and the core width W2 is 100 μm. When the radius of curvature R is 1.5 mm (R / W2 = 15), it is 3.24 dB. When the core width W2 is 200 μm and the radius of curvature R is 3.0 mm (R / W2 = 15), it is 3.23 dB. It can be seen that there is a correlation between them.

  Then, according to the graph of FIG. 4 compiled by the inventor, as described above, the shape of the second core portion of the light-emitting side optical waveguide core is expressed as “the ratio of the curvature radius R to the core width W2 is 15 or more ( R / W2 ≧ 15) ”, that is,“ the curvature radius R (μm) of the curved portion of the second core portion to be bent is 15 times or more the core width W2 (μm) of the second core portion 1c [ By satisfying R ≧ (15 × W2)] ”, it was confirmed that the light loss (bending loss) of the curved portion can be reduced. Therefore, the input device of the present invention has little light loss at the curved portion in the light-emitting side optical waveguide core. Therefore, the light quantity balance between the second core portion having the curved portion and the linear first core portion is reduced. It is easy to design and adjust, and as a result, the light distributed to these two orthogonal sides can be distributed in an ideal state.

  The input device using the frame-shaped optical waveguide according to the present invention does not require high accuracy and the accompanying labor for alignment between the light source and the optical waveguide core, and the light from the light source is transmitted in the optical waveguide frame. Evenly distributed to two orthogonal sides. As a result, this input device can detect a highly accurate input body without a blind spot in the detection space.

DESCRIPTION OF SYMBOLS 1 Light emission side optical waveguide core 1a Common part 1b 1st core part 1c 2nd core part 3 Light emitting element 10 Frame-shaped optical waveguide 10a Corner | angular part S Detection space J Branch point W1 Core width of the 1st core part W2 2nd Core width of core part

Claims (3)

  A frame-shaped optical waveguide disposed around a rectangular detection space, a light-emitting element and a light-receiving element disposed on the rectangular outer edge of the frame-shaped optical waveguide, and positioned at the inner edge of the frame-shaped optical waveguide The position of the input body located in the detection space by detecting the shielding of light reaching the light incident side end of the corresponding light receiving side optical waveguide core from the light emitting side end of the emitted light side optical waveguide core An input device for acquiring information, wherein the light emitting element is disposed in a predetermined direction on an outer edge of one corner of the frame-shaped optical waveguide, and the light emitting element is disposed on two sides of the frame adjacent to the corner. A bifurcated light emitting side optical waveguide core that distributes light emitted from the light source at a predetermined ratio in the two side directions orthogonal to each other, and the bifurcated light emitting side optical waveguide core is in contact with the light emitting element. A common part on the light incident side provided at the corner, A first core portion extending linearly in the direction of one side of the frame along the optical axis of light emission of the light-emitting element, and a curved portion with a predetermined curvature from a branch point of the common portion. A core width (W1) of the linear first core portion at the branch point of the light emitting side optical waveguide core is formed from the second core portion extending in the other side direction of the frame orthogonal to the optical axis. The ratio of the core width (W2) of the curved second core portion to (1)) is 1 or more [(W2 / W1) ≧ 1].   The curved portion of the second core portion of the bifurcated light-emitting side optical waveguide core has a ¼ circular shape, and the radius of curvature (R) is equal to the core width (W2) of the second core portion. The input device according to claim 1, wherein the input device is 15 times or more [R ≧ (15 × W2)].   On the other two sides respectively opposed to the two sides of the frame on which the bifurcated light emitting side optical waveguide core is disposed, the light emitting side light corresponding to each light emitting side end of the light emitting side optical waveguide core is provided. The input device according to claim 1, wherein a plurality of light-receiving side optical waveguide cores are provided for guiding light from the waveguide core to the light receiving element.

Images