JP2015201135A - Position sensor and sheet-like optical waveguide used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position sensor which does not sense unwanted parts, such as a little finger and a base thereof, of a hand holding an input device when inputting information such as characters using an input device such as a pen, and a sheet-like optical waveguide used for the same.SOLUTION: A position sensor (A) includes: a sheet-like optical waveguide (W) comprising a grid of cores 2 sandwiched between an undercladding layer 1 and overcladding layer 3, and a light-emitting element 4 and light-receiving element 5 coupled to respective end faces of the cores 2. Refractive index differences between the cores 2 and the cladding layers 1, 3 are designed to be within a specific range. The cores 2 have a modulus of elasticity that is greater than those of the cladding layers 1, 3. When a surface of the sheet-like optical waveguide (W) is pressed, a deformation rate of a cross-section of each core 2 in a pressing direction is smaller than those of cross-sections of the cladding layers 1, 3. Each intersection of the grid of cores 2 is a discontinuous intersection that is separated by a gap in at least one of intersecting directions.

Description

  The present invention relates to a position sensor that optically detects a pressed position and a sheet-like optical waveguide used therefor.

  Conventionally, a position sensor that optically detects a pressed position has been proposed (see, for example, Patent Document 1). In this, a plurality of cores serving as optical paths are arranged in the vertical and horizontal directions, and the peripheral portions of the cores are covered with a clad to form a sheet, and light from the light emitting element is incident on one end surface of each of the cores, The light transmitted through each core is detected by the light receiving element at the other end surface of each core. When a part of the surface of the sheet-like position sensor is pressed with a finger or the like, the core of the pressed portion is crushed (the cross-sectional area of the core in the pressing direction is reduced). Since the light detection level at the lowering is reduced, the pressed position can be detected.

  On the other hand, what has a pressure-sensitive touch panel and a display is proposed as an input device which inputs a character etc. (for example, refer to patent documents 2). When a character or the like is input on the pressure-sensitive touch panel with a pen, the pressure-sensitive touch panel senses the pressure position of the pen tip and outputs it to the display, and the input character or the like is displayed on the display. It is supposed to be.

JP-A-8-234895 JP 2006-172230 A

  In general, when writing a character or the like on a paper with a writing tool such as a pen, the little finger of the hand holding the writing tool or the base portion (the little finger ball) also contacts the surface of the paper.

  Therefore, when a character or the like is input to the surface of the sheet-like position sensor of Patent Document 1 with a writing instrument such as a pen, not only the pen tip but also the little finger of the hand holding the writing instrument and the base portion thereof are in the sheet-like shape. Since the position sensor is pressed, not only the input characters and the like but also the unnecessary little finger and the base portion thereof are detected.

  Similarly, when inputting characters or the like to the input device of Patent Document 2, the pressure-sensitive touch panel is not only the pressure position by the pen tip, but also the pressure position by the little finger of the hand holding the writing instrument or the base portion thereof. Therefore, not only the inputted characters but also the unnecessary little finger and the base portion thereof are displayed on the display.

  The present invention has been made in view of such circumstances, and when inputting information such as characters with an input body such as a pen, unnecessary portions such as the little finger of the hand holding the input body and the base portion thereof are not sensed. An object of the present invention is to provide a position sensor and a sheet-like optical waveguide used therefor.

  In order to achieve the above object, the present invention provides a sheet-like optical waveguide having a plurality of linear cores formed in a lattice shape, an under cladding layer that supports the cores, and an over cladding layer that covers the cores. A waveguide, a light emitting element connected to one end face of the core, and a light receiving element connected to the other end face of the core, and the amount of light propagation of the core by pressing against an arbitrary place on the surface of itself It is a sheet-like position sensor that identifies a pressing position by a change, and at least one direction where a part or all of the lattice-like intersection formed by the plurality of linear cores intersects is separated by a gap. It is formed at a discontinuous intersection of the state, and the pressing to the position sensor is a pressing by the tip input portion of the input body having a curvature radius R (unit: μm), and the curvature radius R and the core thickness T ( Unit: μm) When the ratio A (= R / T) is used, the refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer has a maximum value Δmax represented by the following formula (1), The minimum value Δmin shown in the formula (2) is set, and the elastic modulus of the core is set larger than the elastic modulus of the under cladding layer and the elastic modulus of the over cladding layer, and the sheet A position sensor in which the deformation ratio of the cross section of the core in the pressing direction is smaller than the deformation ratio of the cross sections of the over clad layer and the under clad layer in the pressed state of the surface of the optical waveguide. And

  Further, the present invention provides a sheet-like optical waveguide used for the position sensor, wherein a plurality of linear cores formed in a lattice shape, an under cladding layer that supports the core, and an over cladding that covers the core And a part or all of the lattice-like intersection formed by the plurality of linear cores is formed in a discontinuous intersection in a state where at least one intersecting direction is divided by a gap, The pressure on the surface of the over clad layer is assumed to be a pressure applied by the tip input portion of the input body having a curvature radius R (unit: μm), and the curvature radius R and the core thickness T (unit: μm) are assumed. )), The refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer has a maximum value Δmax represented by the following formula (1): And expressed by the following formula (2) A sheet-like optical waveguide in which the elastic modulus of the core is set to be larger than the elastic modulus of the under-cladding layer and the elastic modulus of the over-cladding layer. The gist.

  In the present invention, the “deformation rate” refers to a ratio of a change amount of each thickness at the time of pressing to each thickness of the core, the over cladding layer, and the under cladding layer before pressing in the pressing direction.

  When inputting information such as characters with an input body such as a pen on the surface of a position sensor having a sheet-shaped optical waveguide in which a plurality of linear cores are arranged and formed in a lattice shape, the present inventors In order to prevent the part of the hand holding the body from being sensed, research was conducted on the light propagation of the core. In the course of that research, instead of making the core crush (the cross-sectional area is small) by the pressure of the tip of the input body (such as the pen tip) or the hand holding the pen as in the past, The idea was to prevent the core from collapsing with the above pressure (so that the cross-sectional area is maintained). Therefore, the elastic modulus of the core was set to be larger than the elastic modulus of the under cladding layer and the over cladding layer. Then, both the tip input part and the hand part of the input body are deformed so that the over clad layer and the under clad layer are crushed in the pressing direction, and the core maintains the cross-sectional area and the tip input part of the input body. And bent along the hand part so as to sink into the underclad layer 1. The bending of the core was a sharp bend at the tip input portion of the input body and a gentle bend at the hand. As a result, light leakage (scattering) from the core occurs in the core at the tip input part of the input body due to the sharp bending of the core, and the core bending is gentle in the core at the hand part. Therefore, it was found that the light leakage (scattering) does not occur. That is, the detection level (light reception amount) of light at the light receiving element is reduced in the core at the tip input portion of the input body, and the detection level is not reduced in the core at the hand. From this decrease in the light detection level, it is possible to detect the position of the tip input portion of the input body, and the part of the hand where the detection level does not decrease is the same as in the non-pressed state and is found not to be detected. It was.

  Furthermore, the present inventors have conducted research on light leakage (scattering) from the core caused by pressing by the tip input portion of the input body in order to increase the detection accuracy of the position of the tip input portion of the input body. Piled up. In the course of the research, the light leakage (scattering) depends on the refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer, and the refractive index difference Δ is determined by the tip input portion of the input body. It has been determined that it depends on the radius of curvature R and the thickness T of the core. As a result of repeated trial and error, if the refractive index difference Δ is set between the maximum value Δmax expressed by the above equation (1) and the minimum value Δmin expressed by the above equation (2), the input It has been found that the detection accuracy of the position of the tip input part of the body can be improved, and the present invention has been achieved.

  In particular, when one or all of the lattice-like intersections formed by the plurality of linear cores are formed as discontinuous intersections in a state where at least one intersecting direction is divided by a gap, Crossing loss can be reduced. The present inventors have obtained such knowledge.

  In the position sensor of the present invention, the elastic modulus of the core is set larger than the elastic modulus of the under cladding layer and the elastic modulus of the over cladding layer. Therefore, when the surface of the over clad layer of the optical waveguide is pressed, the deformation rate of the cross section of the core in the pressing direction becomes smaller than the deformation rate of the cross section of the over clad layer and the under clad layer, The cross-sectional area is maintained. Then, when information such as characters is input to the surface of the position sensor with an input body such as a pen, the bending state of the core suddenly extends along the front end input section of the input body at the pressing portion by the tip input section such as the pen tip. As a result, light leakage (scattering) from the core occurs, and at the pressed part of the hand holding the input body, the bending of the core becomes gentle along the hand, and the above light leakage (scattering) occurs. Can be prevented from occurring. Therefore, in the core pressed by the tip input part such as a pen tip, the detection level of light in the light receiving element is lowered, and in the core pressed by the hand having the input body, the detection level is not lowered. Can do. The position of the tip input portion such as the pen tip can be detected from the decrease in the detection level of the light, and the portion of the hand where the detection level does not decrease is the same as the unpressed state. Can be prevented. In addition, part or all of the lattice-like intersection formed by the core is formed as a discontinuous intersection in a state in which at least one intersecting direction is divided by a gap, thereby reducing the light intersection loss. be able to. Therefore, the detection sensitivity of the position of the tip input unit such as the pen tip can be increased.

  Further, in the position sensor of the present invention, the refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer is expressed by the maximum value Δmax shown by the above formula (1) and the above formula (2). Therefore, the decrease in the light detection level (light leakage (scattering) from the core) caused by pressing by the tip input part of the input body is optimized and the input value is reduced. The detection accuracy of the position of the tip input part of the body can be increased.

  Also, the sheet-like optical waveguide of the present invention is formed at discontinuous intersections in which at least one intersecting part of the lattice shape formed by a plurality of linear cores is divided by a gap. Therefore, the cross loss of light can be reduced. Furthermore, the sheet-like optical waveguide of the present invention is set so that the elastic modulus of the core is larger than the elastic modulus of the under-cladding layer and the over-cladding layer, so when pressing the surface of the over-cladding layer, The deformation ratio of the cross section of the core in the pressing direction becomes smaller than the deformation ratio of the cross section of the over cladding layer and the under cladding layer, and the cross sectional area of the core in the pressing direction can be maintained. Moreover, in the sheet-like optical waveguide of the present invention, the refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer has a maximum value Δmax expressed by the above formula (1) and the above formula (2). It is set between the minimum value Δmin indicated by. From these facts, the sheet-like optical waveguide of the present invention is effective as the configuration of the position sensor of the present invention.

It is a top view showing typically one embodiment of a position sensor of the present invention. (A) is an enlarged plan view schematically showing an intersection of lattice-shaped cores in the position sensor, and (b) is an enlarged schematic view of a cross section of a central portion of the position sensor. It is an expanded sectional view shown. (A) is an enlarged plan view schematically showing a light path in a continuous intersection, and (b) is an enlarged plan view schematically showing a light path in a discontinuous intersection. (A) is sectional drawing which shows typically the state of the said position sensor pressed by the input body, (b) is sectional drawing which shows typically the state of the said position sensor pressed by the hand. . (A)-(e) is an enlarged plan view which shows typically the modification of the cross | intersection part of the said grid | lattice-like core.

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

  FIG. 1 is a plan view showing an embodiment of the position sensor of the present invention. The position sensor A of this embodiment includes a rectangular sheet-like optical waveguide W having a lattice-like core 2 and a light-emitting element 4 connected to one end face of the linear core 2 constituting the lattice-like core 2. And a light receiving element 5 connected to the other end face of the linear core 2. The light emitted from the light emitting element 4 passes through the core 2 and is received by the light receiving element 5. In FIG. 1, the core 2 is indicated by a chain line, and the thickness of the chain line indicates the thickness of the core 2. In FIG. 1, the number of cores 2 is omitted. And the arrow of FIG. 1 has shown the direction where light travels.

  In this embodiment, each of the intersecting portions of the lattice-like core 2 in the sheet-like optical waveguide W is divided by the gap G in all four intersecting directions as shown in a plan view in FIG. Is discontinuous. The width d of the gap G exceeds 0 (zero) (if the gap G is formed) and is usually set to 20 μm or less. In the sheet-like optical waveguide W, the lattice-like core 2 is supported by a sheet-like under clad layer 1 and covered with a sheet-like over clad layer 3 as shown in a sectional view in FIG. It is formed in the state. In this embodiment, the gap G is formed of a material for forming the over clad layer 3.

  Thus, in the lattice-like core 2, if the crossing portion is discontinuous, the light crossing loss can be reduced. That is, as shown in FIG. 3 (a), in an intersection where all four intersecting directions are continuous, if one of the intersecting directions (upward in FIG. 3 (a)) is noted, the light incident on the intersection A part of the light reaches the wall surface 2a of the core 2 orthogonal to the core 2 through which the light has traveled, and is transmitted through the core 2 because the reflection angle at the wall surface is large [two points in FIG. (See chain line arrow). Such transmission of light also occurs in the direction opposite to the above (downward in FIG. 3A). On the other hand, as shown in FIG. 3 (b), when one intersecting direction (upward in FIG. 3 (b)) is discontinuous by the gap G, the interface between the gap G and the core 2 is Part of the light that is formed and passes through the core 2 in FIG. 3 (a) has a smaller reflection angle at the interface, and thus is reflected at the interface without passing through and continues to travel through the core 2 [FIG. 3 (b), see the two-dot chain line arrow]. Such reflection of light also occurs in the direction opposite to the above (downward in FIG. 3B). For this reason, as described above, when the crossing portion is discontinuous, the light crossing loss can be reduced.

  In the sheet-like optical waveguide W, the elastic modulus of the core 2 is set larger than the elastic modulus of the under cladding layer 1 and the elastic modulus of the over cladding layer 3. Thereby, when the surface of the said sheet-like optical waveguide W is pressed, the deformation rate of the cross section of the core 2 of the pressing direction becomes smaller than the deformation rate of the cross section of the over clad layer 3 and the under clad layer 1. It has become.

  That is, as shown in cross-sectional views in FIGS. 4A and 4B, the position sensor A is placed on a flat table 30 such as a table, and the surface of the position sensor A is placed on the lattice-like core 2. When information such as characters is written in the corresponding area by writing the information such as characters with the input body 10 such as a pen held in the hand 20, the pressing portion by the tip input portion 10a such as the pen tip [see FIG. The pressing part (see FIG. 4 (b)) of the 20 little fingers and the base part (little finger ball) thereof, etc. also collapses the over-cladding layer 3 and the under-cladding layer 1 having a low elastic modulus in the cross section in the pressing direction. The core 2 that is deformed and has a large elastic modulus is bent so as to sink into the under-cladding layer 1 along the tip input portion 10a and the hand 20 while maintaining the cross-sectional area.

  And in the press part by the front-end | tip input part 10a, as shown to Fig.4 (a), since the front-end | tip input part 10a is sharp, the bending condition of the core 2 becomes abrupt and the light from the core 2 is light. Leakage (scattering) occurs [see the two-dot chain arrow in FIG. 4 (a)]. On the other hand, in the pressing portion by the hand 20 having the input body 10, as shown in FIG. 4 (b), the hand 20 is considerably larger and rounder than the tip input portion 10a. The curve becomes gradual and the light leakage (scattering) does not occur (the light travels without leaking through the core 2) (see the two-dot chain line arrow in FIG. 4B). Therefore, the detection level of light at the light receiving element 5 is lowered in the core 2 pressed by the tip input portion 10a, and the detection level is not lowered in the core 2 pressed by the hand 20 having the input body 10. can do. The position (coordinates) of the tip input portion 10a can be detected from the decrease in the light detection level. The portion of the hand 20 whose detection level does not decrease is the same as the state where it is not pressed, and is not sensed.

  At this time, as described above, since the lattice-like intersection formed by the core 2 is formed as a discontinuous intersection, the light intersection loss is reduced. The detection sensitivity of the position of the tip input unit 10a such as the pen tip is high.

  Further, in the position sensor A, the refractive index difference Δ between the core 2 and the under-cladding layer 1 and the over-cladding layer 3 has a maximum value Δmax expressed by the following formula (1) and the following formula (2). It is set to a value between the indicated minimum value Δmin. Thereby, the detection accuracy of the position of the front-end | tip input part 10a is raised. In the following formulas (1) and (2), A is the ratio between the radius of curvature R (unit: μm) of the tip input portion 10a such as a pen tip and the thickness T (unit: μm) of the core 2 ( R / T).

  That is, when the refractive index difference Δ is larger than the maximum value Δmax, the amount of light leakage (scattering) is small even when pressed by the tip input portion 10a, and the light detection level at the light receiving element 5 is sufficiently lowered. Therefore, the position of the tip input unit 10a and the position of the hand 20 cannot be distinguished with high accuracy. On the other hand, if the refractive index difference Δ is smaller than the minimum value Δmin, light leakage (scattering) occurs even in the pressed portion by the hand 20, and the position of the tip input portion 10a and the position of the hand 20 are highly distinguished. It will not be accurate.

Here, for example, the radius of curvature R (unit: μm) of the tip input portion 10a is in the range of 100 to 1000, the thickness T (unit: μm) of the core 2 is in the range of 10 to 100, and the ratio A is 1 to 1. If it is in the range of 100, the refractive index difference Δ is in the range of 1.0 × 10 ^{−3 to} 7.95 × 10 ⁻² . When the ratio A exceeds 100, the minimum value Δmin is set to 1.0 × 10 ⁻³ (constant).

  Then, the position of the tip input unit 10a detected by the position sensor A and the movement locus (characters, drawings, etc.) of the tip input unit 10a in which the position is continuous are stored in a storage unit such as a memory as electronic data, for example. Or sent to the display and displayed on the display.

  The input body 10 only needs to be able to press the surface of the position sensor A as described above, and may be not only a writing instrument that can be written on paper with ink or the like, but also a simple rod that cannot be written on paper with ink or the like. Further, when the pressing is released (the tip input part 10a moves or the input such as writing ends), the under cladding layer 1, the core 2 and the over cladding layer 3 are each restored by their own restoring force. Return to the original state (see FIG. 2B). The submerged depth D of the core 2 into the under cladding layer 1 is preferably up to 2000 μm. If it exceeds that, the under cladding layer 1, the core 2 and the over cladding layer 3 may not return to their original state, or the optical waveguide W may be cracked.

  Here, the elastic modulus and the like of the core 2, the under cladding layer 1 and the over cladding layer 3 will be described in more detail.

  The elastic modulus of the core 2 is preferably in the range of 1 GPa to 10 GPa, more preferably in the range of 2 GPa to 5 GPa. When the elastic modulus of the core 2 is less than 1 GPa, the cross-sectional area of the core 2 may not be maintained due to the pressure of the tip input portion 10a due to the shape of the tip input portion 10a such as a pen tip (the core 2 may be crushed). There is a possibility that the position of the tip input portion 10a cannot be detected properly. On the other hand, when the elastic modulus of the core 2 exceeds 10 GPa, the bending of the core 2 due to the pressure of the tip input portion 10a may be a gentle bend without being a sharp bend along the tip input portion 10a. Therefore, light leakage (scattering) from the core 2 does not occur, and the light detection level at the light receiving element 5 does not decrease, so that the position of the tip input portion 10a may not be detected properly. In addition, the dimension of the core 2 is set in the range whose thickness is 5-100 micrometers, for example, and whose width is 1-300 micrometers.

  The elastic modulus of the over clad layer 3 is preferably in the range of 0.1 MPa or more and less than 10 GPa, more preferably in the range of 1 MPa or more and less than 5 GPa. If the elastic modulus of the over clad layer 3 is less than 0.1 MPa, it is too soft and may be damaged by the pressure of the tip input portion 10a due to the shape of the tip input portion 10a such as a pen tip, protecting the core 2 Can not do. On the other hand, when the elastic modulus of the over clad layer 3 is 10 GPa or more, the core 2 is crushed and the position of the tip input portion 10a is properly detected by the pressure of the tip input portion 10a and the hand 20 without being crushed. It may not be possible. In addition, the thickness of the over clad layer 3 is set in the range of 1 to 200 μm, for example.

  The elastic modulus of the under cladding layer 1 is preferably in the range of 0.1 MPa to 1 GPa, more preferably in the range of 1 MPa to 100 MPa. When the elastic modulus of the under clad layer 1 is less than 0.1 MPa, the under clad layer 1 is too soft and may not be continuously performed after being pressed by the tip input portion 10a such as a pen tip and not returned to the original state. On the other hand, when the elastic modulus of the underclad layer 1 exceeds 1 GPa, the core 2 is crushed and the position of the tip input portion 10a cannot be detected properly even if the tip input portion 10a or the pressure of the hand 20 is crushed. There is a fear. In addition, the thickness of the under clad layer 1 is set in the range of 20-2000 micrometers, for example.

  Examples of the material for forming the core 2, the under cladding layer 1 and the over cladding layer 3 include a photosensitive resin and a thermosetting resin, and the optical waveguide W can be manufactured by a manufacturing method corresponding to the forming material. . The refractive index of the core 2 is set larger than the refractive indexes of the under cladding layer 1 and the over cladding layer 3. The elastic modulus and refractive index can be adjusted by, for example, selecting the type of each forming material and adjusting the composition ratio. Note that a rubber sheet may be used as the undercladding layer 1 and the cores 2 may be formed in a lattice shape on the rubber sheet.

  Further, an elastic layer such as a rubber layer may be provided on the back surface of the under cladding layer 1. In this case, even if the restoring force of the under-cladding layer 1, the core 2 and the over-cladding layer 3 is weak or they are originally made of a material having a weak restoring force, the elastic force of the elastic layer is utilized. Thus, the weak restoring force is assisted, and after the pressing by the distal end input portion 10a of the input body 10 is released, the original state can be restored.

  In the above embodiment, the crossing portion of the lattice-like core 2 is a discontinuous crossing (see FIG. 2A) in which all four intersecting directions are discontinuous (see FIG. 2A). It may be an intersection. For example, as shown in FIG. 5 (a), only one intersecting direction may be divided by the gap G to be discontinuous, or as shown in FIGS. 5 (b) and 5 (c), The two intersecting directions (FIG. 5 (b) is the two opposing directions, FIG. 5 (c) is the two adjacent directions) may be discontinuous, or as shown in FIG. 5 (d) The three directions may be discontinuous. Further, two or more of the discontinuous intersections shown in FIGS. 2 (a) and 5 (a) to 5 (d) and continuous intersections in which all four intersecting directions are continuous [see FIG. 5 (e)]. It is good also as the grid | lattice form provided with no intersection.

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

[Formation material of over clad layer]
Component A: 30 parts by weight of epoxy resin (Epogosei PT, Yokkaichi Gosei Co., Ltd.).
Component B: 70 parts by weight of an epoxy resin (manufactured by Daicel, EHPE3150).
Component C: 4 parts by weight of a photoacid generator (manufactured by Sun Apro, CPI 200K).
Component D: 100 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries).
By mixing these components A to D, a material for forming the over clad layer was prepared.

[Core forming material]
Component E: 80 parts by weight of an epoxy resin (manufactured by Daicel, EHPE3150).
Component F: 20 parts by weight of an epoxy resin (manufactured by Nippon Steel Chemical Co., Ltd., YDCN700-10).
Component G: 1 part by weight of a photoacid generator (manufactured by ADEKA, SP170).
Component H: 50 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries).
The core forming material was prepared by mixing these components E to H.

[Formation material of under cladding layer]
Component I: 75 parts by weight of an epoxy resin (Epogosei PT, manufactured by Yokkaichi Gosei Co., Ltd.)
Component J: 25 parts by weight of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, JER1007).
Component K: 4 parts by weight of a photoacid generator (manufactured by Sun Apro, CPI 200K).
Component L: 50 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries).
By mixing these components I to L, an under cladding layer forming material was prepared.

[Production of optical waveguide]
An over clad layer was formed on the surface of the glass substrate by spin coating using the over clad layer forming material. The over cladding layer had a thickness of 5 μm, an elastic modulus of 1.2 GPa, and a refractive index of 1.503.

  Next, a lattice-like core was formed on the surface of the over clad layer by photolithography using the core forming material. Each lattice-like intersection is a discontinuous intersection in which all four intersecting directions are separated by a gap and are discontinuous [see FIG. 2 (a)]. . The width of the gap was 10 μm. The core had a thickness of 30 μm, the core width of the lattice portion was 100 μm, the pitch was 600 μm, the elastic modulus was 3 GPa, and the refractive index was 1.523.

  Next, an under clad layer was formed on the surface of the over clad layer by spin coating using the under clad layer forming material so as to cover the core. The thickness of the under cladding layer (thickness from the surface of the over cladding layer) was 200 μm, the elastic modulus was 3 MPa, and the refractive index was 1.503.

  And what stuck the double-sided tape (thickness 25 micrometers) on the single side | surface of the board | substrate (thickness 1mm) made from PET was prepared. Next, the other adhesive surface of the double-sided tape was attached to the surface of the under cladding layer, and in this state, the over cladding layer was peeled from the glass substrate.

[Comparative Example]
[Formation material of over clad layer]
Component M: 40 parts by weight of epoxy resin (Epogosei PT, Yokkaichi Gosei Co., Ltd.).
Component N: 60 parts by weight of epoxy resin (Daicel, 2021P).
Component O: 4 weight part of photo-acid generators (made by ADEKA, SP170).
By mixing these components M to O, a material for forming the over clad layer was prepared.

[Core forming material]
Component P: 30 parts by weight of an epoxy resin (Epogosei PT, manufactured by Yokkaichi Gosei Co., Ltd.)
Component Q: 70 parts by weight of an epoxy resin (manufactured by DIC, EXA-4816).
Component R: 4 weight part of photo-acid generators (made by ADEKA, SP170).
The core forming material was prepared by mixing these components P to R.

[Formation material of under cladding layer]
Component S: 40 parts by weight of an epoxy resin (Epogosei PT, manufactured by Yokkaichi Gosei Co., Ltd.)
Component T: 60 weight part of epoxy resins (Daicel, 2021P).
Component U: 4 parts by weight of a photoacid generator (ADEKA, SP170).
By mixing these components S to U, a material for forming the under cladding layer was prepared.

[Production of optical waveguide]
In the same manner as in the above example, an optical waveguide having the same dimensions was produced. However, the elastic modulus was 1 GPa for the over clad layer, 25 MPa for the core, and 1 GPa for the under clad layer. The refractive index was 1.504 for the over clad layer, 1.532 for the core, and 1.504 for the under clad layer.

[Production of position sensor]
A light emitting element (Optowell, XH85-S0603-2s) is connected to one end face of the core of each of the optical waveguides of the above examples and comparative examples, and a light receiving element (Hamamatsu Photonics, s10226) is connected to the other end face of the core. The position sensors of Examples and Comparative Examples were manufactured.

[Evaluation of position sensor]
The tip of the ballpoint pen (curvature radius 350 μm) was pressed with a load of 1.47 N on the surface of each position sensor, and the human index finger (curvature radius 1 cm) was pressed with a load of 19.6 N. Then, the light detection level (light reception amount) at the light receiving element was measured when the load was not applied and when it was applied, and the attenuation rate was calculated according to the following equation (3).

  As a result, in the position sensor of the example, the attenuation rate when the pen tip was pressed was 80%, and the attenuation rate when the index finger was pressed was 0%. On the other hand, in the position sensor of the comparative example, the attenuation rate when the pen tip was pressed was 60%, and the attenuation rate when the index finger was pressed was 50%.

  That is, in the position sensor of the embodiment, the light detection level at the light receiving element decreases when the pen tip is pressed and does not decrease when the index finger is pressed, so only the position of the pen tip can be detected. It is the same as the state where it is not pressed, and it can be seen that it is not sensed. On the other hand, in the position sensor of the comparative example, the light detection level at the light receiving element is reduced to the same extent both when the pen tip is pressed and when the index finger is pressed. It can be seen that.

Note that, as described above, the radius of curvature R of the pen tip of the ballpoint pen is 350 μm, and the thickness A of the core is 30 μm in both the example and the comparative example. Therefore, the ratio A (= R / T) is 11.7. The maximum value Δmax of the refractive index difference Δ between the core and the under cladding layer and the over cladding layer is 7.4 × 10 ⁻² from the above equation (1), and the minimum value Δmin is All are 9.8 * 10 < ^-3 > from said Formula (2). That is, the refractive index difference Δ (= 0.020) of the example and the refractive index difference Δ (= 0.028) of the comparative example are set to values between the maximum value Δmax and the minimum value Δmin. .

  Moreover, the same tendency as in the above-described embodiment is also obtained when each of the intersecting portions of the lattice-shaped core is a discontinuous intersection [see FIGS. 5A to 5D] in which the intersecting 1 to 3 directions are discontinuous. The result which shows was obtained. Further, a discontinuous intersection in which the intersecting 1 to 4 directions are discontinuous (see FIGS. 2A and 5A to 5D) and a continuous intersection in which all of the 4 intersecting directions are continuous [ As shown in FIG. 5 (e)], a result showing the same tendency as in the above-described example was obtained even in a lattice shape having two or more types of intersections.

  The position sensor of the present invention detects only the position and movement locus of the tip input unit such as a necessary pen tip when inputting a character or the like while holding an input body such as a pen, etc. It can be used to prevent detection. And the sheet-like optical waveguide of this invention can be utilized as a structure of the said position sensor.

A position sensor W sheet-like optical waveguide 1 under clad layer 2 core 3 over clad layer 4 light emitting element 5 light receiving element

Claims (2)

A sheet-like optical waveguide having a plurality of linear cores formed in a lattice shape, an under clad layer that supports the core, and an over clad layer that covers the core, and is connected to one end face of the core A sheet-like position that includes a light-emitting element and a light-receiving element connected to the other end surface of the core, and identifies a pressing position by a change in the amount of light propagation of the core due to pressing to an arbitrary position on the surface of itself In the sensor, a part or all of the lattice-like intersection formed by the plurality of linear cores is formed as a discontinuous intersection in a state where at least one intersecting direction is divided by a gap, The pressure applied to the position sensor is a pressure applied by the tip of the input body having a curvature radius R (unit: μm), and the ratio A (= R / R) between the curvature radius R and the core thickness T (unit: μm). T) The difference in refractive index Δ between the under-cladding layer and the over-cladding layer is between the maximum value Δmax expressed by the following formula (1) and the minimum value Δmin expressed by the following formula (2). The elastic modulus of the core is set to be larger than the elastic modulus of the under-cladding layer and the over-cladding layer, and in the pressing state of the surface of the sheet-like optical waveguide, A position sensor, wherein a deformation ratio of a cross section of a core is smaller than a deformation ratio of a cross section of an over clad layer and an under clad layer.

A sheet-like optical waveguide used for the position sensor according to claim 1, wherein a plurality of linear cores formed in a lattice shape, an under clad layer that supports the core, and an over clad layer that covers the core And part or all of the lattice-like intersection formed by the plurality of linear cores is formed as a discontinuous intersection in a state where at least one intersecting direction is divided by a gap, Assuming that the pressure on the surface of the over clad layer is pressed by the tip of the input body having a curvature radius R (unit: μm), the curvature radius R and the core thickness T (unit: μm) When the ratio A (= R / T) is used, the refractive index difference Δ between the core and the under-cladding layer and the over-cladding layer has a maximum value Δmax represented by the following formula (1): It is shown by the following formula (2) A sheet-like optical waveguide characterized in that the elastic modulus of the core is set larger than the elastic modulus of the under-cladding layer and the elastic modulus of the over-cladding layer. .

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