WO2016047448A1

WO2016047448A1 - Position sensor

Info

Publication number: WO2016047448A1
Application number: PCT/JP2015/075679
Authority: WO
Inventors: 良真吉岡; 裕介清水; 柴田　直樹
Original assignee: 日東電工株式会社
Priority date: 2014-09-24
Filing date: 2015-09-10
Publication date: 2016-03-31
Also published as: TW201614459A; JP2016066176A

Abstract

　The present invention provides a position sensor with which it is possible to reduce a space. This position sensor is provided with a sheet-shaped optical waveguide W in which a sheet-shaped core pattern member provided with a lattice-shaped portion 2A comprising a plurality of linear cores 2 and an outer peripheral portion 2B extended from the core 2 of the lattice-shaped portion 2A and arranged in bent form so as to be along the outer periphery of the lattice-shaped portion 2A is covered with an under-cladding layer 1 and an over-cladding layer 3. The refractive index of the clad layer covering circular arc portions 2p, 2q in which the core 2 of the outer peripheral portion 2B is bent is set to be lower than the refractive indices of the under-cladding layer 1 and over-cladding layer 3 covering the other portions of the core 2. The light propagating through the circular arc portions 2p, 2q is thereby made less susceptible to leakage even when the bend radii of the circular arc portions 2p, 2q are reduced.

Description

Position sensor

The present invention relates to a position sensor that optically detects a pressed position.

The present applicant has proposed a position sensor that optically detects the pressed position (see, for example, Patent Document 1). As shown in FIG. 6, this has a rectangular sheet-shaped optical waveguide W <b> 1 in which a sheet-shaped core pattern member is sandwiched between a rectangular sheet-shaped under cladding layer 11 and an over cladding layer 13. The core pattern member includes a lattice portion 12A having a plurality of continuous lattices in which linear optical path cores 12 are arranged vertically and extending from the core 12 of the lattice portion 12A. Outer peripheral portions 12B to 12E arranged along the outer periphery of the cylindrical portion 12A. The light emitting element 14 is connected to the end of the core 12 of the outer peripheral portion 12B of the core pattern member, and the light receiving element 15 is connected to the end of the core 12 of the outer

peripheral portions

12D and 12E. The light emitted from the light-emitting element 14 passes through the core 12 of the outer

peripheral portions

12B and 12C connected to the light-emitting element 14 through the core 12 of the lattice-shaped portion 12A, and the core 12 of the opposite outer

peripheral portions

12D and 12E. And the light receiving element 15 receives the light. A surface portion of the over cladding layer 13 corresponding to the lattice portion 12A (a rectangular portion indicated by a one-dot chain line in a state surrounding the lattice portion 12A in FIG. 6) is an input region 13A of the position sensor.

When inputting, an arbitrary portion of the input area 13A is pressed with, for example, an input pen tip. Thereby, the core 12 of the pressing portion is deformed, and the light propagation amount of the core 12 having the deformed portion is reduced. For this reason, in the core 12 of the pressing portion, the light receiving level at the light receiving element 15 decreases, so that the decrease in the light receiving level can be processed by a computer and the pressed position can be detected.

In general, in the optical waveguide, the refractive index of the core serving as the optical path is set higher than the refractive indexes of the under-cladding layer and the over-cladding layer, and the light propagating in the core is reflected in the core while reflecting in the core. Propagated and less likely to leak into the under-cladding layer and over-cladding layer In the optical waveguide W1, the under cladding layer 11 and the over cladding layer 13 covering the lattice portion 12A of the core pattern member also cover the outer peripheral portions 12B to 12E from the viewpoint of facilitating manufacture. And the over clad layer 13 is also the same (that is, the same refractive index), which is common technical knowledge.

Japanese Patent No. 5513656

Generally, in this type of position sensor, a light emitting element and a light receiving element are mounted on an electric circuit board. From the viewpoint of reducing the manufacturing cost by making the electric circuit board as compact as possible, the light emitting element and the light receiving element are combined. It is common technical knowledge to place them close together. Actually, in the position sensor shown in FIG. 6, both the light emitting element 14 and the light receiving element 15 are provided on one side (the lower end side in FIG. 6) of the rectangular sheet-shaped optical waveguide W1. Are placed close together.

In general, in this type of position sensor, it is common technical knowledge to reduce the number of light emitting elements and light receiving elements as much as possible from the viewpoint of manufacturing cost. Actually, one position sensor is used in each of the position sensors shown in FIG.

As described above, since the arrangement and the number of the light emitting elements 14 and the light receiving elements 15 are limited in terms of manufacturing cost, the light emitted from one light emitting element 14 is in the vertical direction of the lattice-shaped portion 12A. In order to be propagated to the core 12 in the two horizontal directions (XY directions), it is necessary to branch once by 90 ° along the vertical and horizontal side surfaces of the lattice-shaped portion 12A. Therefore, in the position sensor shown in FIG. 6, the core 12 connected to the light emitting element 14 has a corner portion (in FIG. 6) along the side surface (left side surface in FIG. 6) of the lattice portion 12 </ b> A. A linear portion (reference numeral 12q) that extends to the upper left corner (reference numeral 12p), is bent 90 ° in an arc shape from the tip (reference numeral 12t), and is 180 ° (inverted U-shape) in an arc shape from the tip. ) Branched into a linear part (reference numeral 12r) which is bent (reference numeral 12u) and extends. The

cores

12p, 12q, and 12r on the light emitting element 14 side are thick from the light emitting element 14 to start branching into a plurality of vertical and horizontal cores 12s constituting the lattice portion 12A, and the number of branches increases from there to the tip side. It gradually gets thinner as you go. This is because the light emitted from the light emitting element 14 is sequentially branched from the side closer to the light emitting element 14, so that the core 12 near the light emitting element 14 is thicker and the core 12 far from the light emitting element 14 is thinner.

However, the two

arcuate portions

12t and 12u are set to have large bending radii so that light hardly leaks and propagates gently in the two

arcuate portions

12t and 12u that are the branched portions. In general, when the bending radius of the core is small, light propagating through the core is likely to leak from the bent portion. Therefore, the bending radius of the two arc-

shaped portions

12t and 12u of the outer peripheral portion (the outer peripheral portion on the left side in FIG. 6) 12B where the branch portion is formed is increased, and the outer peripheral portion 12B is formed. The width (frame width) of the peripheral portion F1 of the optical waveguide W1 is also increased. As a result, the position sensor requires a large space. In this respect, the position sensor has room for improvement.

The present invention has been made in view of such circumstances, and an object thereof is to provide a position sensor capable of saving space.

In order to achieve the above object, a position sensor according to the present invention includes a lattice portion having a plurality of lattices in which linear cores are arranged vertically and horizontally, and a core extending from the lattice portion. A sheet-like core pattern member provided with a sheet-shaped core pattern member provided with an outer peripheral portion arranged in a bent state along the outer periphery of the lattice-like portion, and a core of the optical waveguide connected with a sheet-like optical waveguide coated with a clad layer In order to reduce the leakage of light propagating through the bent portion, the refractive index of the cladding layer covering the bent portion of the core of the outer peripheral portion The refractive index of the cladding layer covering the core of the other portion is set lower than the refractive index of the cladding layer, and the surface portion of the cladding layer corresponding to the lattice portion of the core pattern member is used as the input region. The pressed position definitive, a configuration that identifies the light propagation quantity of the core that has changed by the pressing.

In the present invention, the portion of the clad layer that covers the bent portion of the core at the outer peripheral portion of the core pattern member means that it includes an air clad (a clad made of air). That is, the bent part of the core covered with the air clad is in a state exposed to the outside.

The inventors of the present invention have repeated research with a focus on reducing the bending radius of the core at the outer peripheral portion of the core pattern member in order to save the pressing position. Specifically, by reducing the refractive index of the clad layer that covers the core pattern member, the difference in refractive index with the core is increased, and even if the bending radius of the core is reduced, the light propagating through the core Researched the idea to make it difficult to leak.

However, if the difference between the refractive index of the cladding layer and the refractive index of the core is increased as described above, this time, in the input region (the portion corresponding to the lattice-shaped portion of the core pattern member), light from the core of the pressing portion is also emitted. Is less likely to leak, and the difference in light intensity between the pressed portion and other portions is reduced. For this reason, a decrease in the light receiving level at the light receiving element cannot be detected, and the detection sensitivity of the pressed position decreases.

Therefore, the present inventors are not bound by such a concept, the refractive index of the cladding layer, the portion that covers the bent portion of the core of the outer peripheral portion of the core pattern member, and the portion that covers the other core portion With the idea of providing a difference, the former refractive index was set lower. As a result, the difference in refractive index between the core and the clad layer is large in the bent portion of the core and small in the lattice-like portion (input region). Therefore, even if the bending radius of the core is reduced, light propagating through the bending portion is less likely to leak at the bent portion of the core, and light easily leaks from the core at the pressing portion at the lattice-like portion (input region). . That is, by providing a difference in the refractive index in the cladding layer, the bending radius of the core can be reduced to save space in the position sensor, and the detection sensitivity of the pressed position should be excellent. The present invention has been completed.

In the position sensor of the present invention, the core of the outer peripheral portion where the core of the lattice portion is extended is arranged in a state bent along the outer periphery of the lattice portion, and the clad layer covering the bent portion Is set to be lower than the refractive index of the cladding layer covering the core of the other part. Therefore, even if the bending radius of the core is reduced, light propagating through the bending portion is less likely to leak at the bent portion of the core, and light easily leaks from the core at the pressing portion at the lattice-like portion (input region). . That is, the position sensor of the present invention can reduce the bending radius of the core due to the difference in the refractive index in the cladding layer, thereby saving the space of the position sensor and being excellent in detection sensitivity of the pressed position. Can be.

(A) is a top view which shows typically 1st Embodiment of the position sensor of this invention, (b) is an expanded sectional view of the center part. It is a top view which shows the modification of the said position sensor typically. It is a principal part expanded sectional view which shows typically the modification of the optical waveguide which comprises the said position sensor. (A) to (f) are enlarged plan views schematically showing the crossing form of the cores of the lattice-like portion in the position sensor. (A), (b) is an enlarged plan view which shows typically the course of the light in the cross | intersection part of the core of the said lattice-shaped part. It is a top view which shows the conventional position sensor typically.

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

FIG. 1 (a) is a plan view showing a first embodiment of the position sensor of the present invention, and FIG. 1 (b) is an enlarged cross-sectional view of the central portion thereof. The position sensor of this embodiment is the same as that of the conventional position sensor shown in FIG. 6, but two arc-shaped

portions

2p and 2q branched from the core 2 connected to the light emitting element 4 [the upper left corner portion in FIG. Is not covered with the overcladding layer 3 but is exposed and formed with a small bending radius. Then, by reducing the bending radius, the width of the left side shown in the figure is made narrower than that of the conventional one (see FIG. 6), and the position sensor is saved in space (miniaturized). The other parts are the same as those of the conventional position sensor shown in FIG.

That is, the two arc-shaped

portions

2p and 2q of the core 2 in the position sensor of this embodiment are covered with an air clad that is a clad made of air. Here, for example, the refractive index of the core 2 is about 1.51, the under cladding layer 1 and the over cladding layer 3 are about 1.50, and the air cladding is about 1.00. From this, the difference in refractive index (about 0.51) between the two arc-shaped

portions

2p, 2q of the core 2 and the air clad is the two arc-shaped portions of the core 12 in the conventional position sensor shown in FIG. The difference in refractive index between 12t and 12u and the overcladding layer 13 (about 0.01) is much larger. For this reason, even if the bending radii of the two arc-shaped

portions

2p and 2q of the core 2 are reduced, light propagating through the arc-shaped

portions

2p and 2q is difficult to leak, and proper light propagation is possible. Yes. Therefore, as described above, the space of the position sensor is reduced by reducing the bending radii of the two

arcuate portions

2p and 2q of the core 2.

Further, in the lattice portion 2A (input region 3A) other than the two arc-shaped

portions

2p and 2q of the core 2, the difference in refractive index between the core 2, the under cladding layer 1 and the over cladding layer 3 is as shown in FIG. As with the conventional position sensor shown in FIG. Therefore, in the input region 3A, the core 2 of the pressing portion is deformed and light is likely to leak from the core 2 as in the conventional position sensor shown in FIG. And in the core 2 of the said press part, the light reception level in the said light receiving element 5 falls appropriately. For this reason, the position sensor has excellent detection sensitivity of the pressed position without being lowered. In FIG. 1A, the number of the cores 2 of the lattice-like portion 2A is omitted, and the interval between the cores 2 is increased.

The position sensor according to this embodiment is manufactured by, for example, a photolithography method. That is, first, after forming the under-cladding layer 1, the core 2 is patterned on the core pattern member on the surface of the under-cladding layer 1. Next, an over clad layer 3 is patterned on the surface of the under clad layer 1 so as to cover the core pattern member excluding the two arc-shaped

portions

2p and 2q of the core 2. The light emitting element 4 is connected to one end face of the core 2 of the outer peripheral portion 2B of the core pattern member, and the light receiving element 5 is connected to the other end face of the core 2 (end face of the core 2 of the outer

peripheral portions

2D and 2E). To do. In this way, the position sensor can be manufactured.

Here, the thickness of each of the above layers is set, for example, in the range of 10 to 500 μm for the under cladding layer 1, in the range of 5 to 100 μm for the core 2, and in the range of 1 to 200 μm for the over cladding layer 3. 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.

In the position sensor, it is preferable that the elastic modulus of the core 2 is set to be larger than the elastic modulus of the under cladding layer 1 and the over cladding layer 3. The reason is that if the elastic modulus is set in the opposite direction, the periphery of the core 2 becomes hard, so that the optical waveguide having an area considerably larger than the area of the pen tip or the like that presses the input region 3A portion of the over clad layer 3 This is because the W portion is recessed and it is difficult to accurately detect the pressed position. Therefore, as each elastic modulus, for example, the elastic modulus of the core 2 is set within a range of 1 GPa or more and 10 GPa or less, and the elastic modulus of the over clad layer 3 is set within a range of 0.1 GPa or more and less than 10 GPa, The elastic modulus of the under cladding layer 1 is preferably set within a range of 0.1 MPa to 1 GPa. In this case, since the elastic modulus of the core 2 is large, the core 2 is not crushed by a small pressing force (the cross-sectional area of the core 2 is not reduced), but the optical waveguide W is recessed by the pressing, and therefore corresponds to the recessed portion. Light leakage (scattering) occurs from the bent portion of the core 2, and in the core 2, the light receiving level at the light receiving element 5 decreases, so that the pressed position can be detected.

The second embodiment of the position sensor of the present invention is the same as the first embodiment shown in FIGS. 1 (a) and 1 (b), in which the air cladding portion has a refractive index (1) of the over cladding layer 3. ..50)) and a second over clad layer having a lower refractive index (about 1.48). Other parts are the same as those in the first embodiment.

In the second embodiment, the two arc-shaped

portions

2p and 2q branched from the core 2 connected to the light emitting element 4 are covered with the second over clad layer. The difference in refractive index (about 0.03) between the two arc-shaped

portions

2p, 2q of the core 2 and the second over clad layer is the difference between the two cores 2 in the first embodiment. Two arc-shaped

portions

12t and 12u of the core 12 and the over-cladding layer in the conventional position sensor shown in FIG. 6 are smaller than the difference in refractive index (approximately 0.51) between the arc-shaped

portions

2p and 2q and the air cladding. This is larger than the difference in refractive index from 13 (about 0.01). Therefore, also in the second embodiment, the position sensor can be saved in space by reducing the bending radii of the two arc-shaped

portions

2p and 2q of the core 2 as in the first embodiment. be able to.

In the third embodiment of the position sensor of the present invention, two arc-shaped

portions

2p and 2q of the core 2 are formed in the first embodiment shown in FIGS. The portion of the underclad layer that is present is a second underclad layer having a lower refractive index (about 1.48) than the refractive index of other underclad layers 1 (about 1.50). Other parts are the same as those in the first embodiment.

In the third embodiment, the two arc-shaped

portions

2p and 2q branched from the core 2 connected to the light emitting element 4 are formed on the surface of the second under cladding layer and exposed. (Covered with air clad). The difference in refractive index (about 0.03) between the second undercladding layer and the two arc-shaped

portions

2p and 2q of the core 2 is the same as that of the undercladding layer 1 in the first embodiment and the above. It is larger than the difference in refractive index (about 0.01) between the two

arcuate portions

2p and 2q of the core 2. Thereby, in the third embodiment, the light propagating through the two arc-shaped

portions

2p and 2q of the core 2 is more difficult to leak. Therefore, also in the third embodiment, as in the first embodiment, the position sensor can be saved in space by reducing the bending radii of the two

arcuate portions

2p and 2q of the core 2. be able to.

In the fourth embodiment of the position sensor according to the present invention, in the third embodiment, the two arc-shaped

portions

2p and 2q branching the core 2 connected to the light emitting element 4 are The second over clad layer having a low refractive index in the embodiment is covered. The other parts are the same as in the third embodiment.

In the fourth embodiment, the two arc-shaped

portions

2p and 2q branching the core 2 connected to the light emitting element 4 are the second refractive index second under cladding layer in the third embodiment. And is covered with the second over-cladding layer having a low refractive index in the second embodiment. The difference in refractive index (about 0.03) between the two arc-shaped

portions

2p and 2q of the core 2 and the second under cladding layer and the second over cladding layer is the same as the conventional one shown in FIG. This is larger than the difference in refractive index (about 0.01) between the two arc-shaped

portions

12t and 12u of the core 12 and the under cladding layer 11 and the over cladding layer 13 in the position sensor. Thereby, in the fourth embodiment, light propagating through the two arc-shaped

portions

2p and 2q of the core 2 is further less likely to leak. Therefore, also in the fourth embodiment, as in the third embodiment, the position sensor can be saved in space by reducing the bending radii of the two arc-shaped

portions

2p and 2q of the core 2. be able to.

The fifth embodiment of the position sensor according to the present invention is different from the first embodiment shown in FIGS. 1A and 1B in that the two arc-shaped

portions

2p and 2q of the core 2 from the light emitting element 4 are used. Up to, it is not covered with the over clad layer 3 but exposed (covered with air clad). Other parts are the same as those in the first embodiment.

In the fifth embodiment, light propagating from the light emitting element 4 through the two arc-shaped

portions

2p and 2q of the core 2 is less likely to leak. Therefore, also in the fifth embodiment, as in the first embodiment, the position sensor can be saved in space by reducing the bending radii of the two arc-shaped

portions

2p, 2q of the core 2. be able to.

The sixth embodiment of the position sensor according to the present invention is the portion of the under cladding layer in which the core 2 from the light emitting element 4 to the two

arcuate portions

2p and 2q is formed in the fifth embodiment. However, this is the second under-cladding layer having a low refractive index in the third embodiment. The other parts are the same as those in the fifth embodiment.

In the sixth embodiment, the core 2 from the light emitting element 4 to the two

arcuate portions

2p and 2q is formed on the surface of the second under cladding layer having a low refractive index in the third embodiment. It is formed and exposed (covered with air cladding). The difference in refractive index (about 0.03) between the second under-cladding layer and the core 2 from the light emitting element 4 to the two

arcuate portions

2p and 2q is the same as in the fifth embodiment. This is larger than the difference in refractive index (about 0.01) between the undercladding layer 1 and the core 2 from the light emitting element 4 to the two

arcuate portions

2p and 2q. Thereby, in the sixth embodiment, light propagating through the core 2 from the light emitting element 4 to the two

arcuate portions

2p and 2q is more difficult to leak. Therefore, in the sixth embodiment as well, as in the fifth embodiment, the space radius of the position sensor is reduced by reducing the bending radii of the two arc-shaped

portions

2p and 2q of the core 2. be able to.

In each of the above embodiments, the cladding layer covering a part including the bent part of the core of the outer peripheral part of the core pattern member has been described, but the cladding layer covering the entire outer peripheral part of the core pattern member is also described. You may make it the same as that of each said embodiment.

Further, in each of the above embodiments, one light emitting element 4 and one light receiving element 5 are used and arranged on one side of the rectangular shape of the optical waveguide W, but may be other, for example, shown in a plan view in FIG. As described above, two light emitting elements 4 and two light receiving elements 5 may be used and arranged on one side of the optical waveguide W (the lower end side in FIG. 2). FIG. 2 shows a form corresponding to the first embodiment (FIG. 1A).

In other words, the core 2 connected to one of the two light emitting elements 4 (the left end in FIG. 2) is connected to the lattice along one side surface (the left side surface in FIG. 2) of the lattice portion 2A. Extends to one corner (upper left corner in FIG. 2), is bent in an inverted U shape (reference numeral 2r) from the tip, and is branched to each core 2 in the lateral direction of the lattice-shaped portion 2A. . Then, the core 2 reaches one of the two light receiving elements 5 (right side in FIG. 2) through the lattice-shaped portion 2A.

The core 2 connected to the remaining one (right end in FIG. 2) of light emitting elements 4 is connected to the other corners of the grid portion 2A along the other side surface (right side surface in FIG. 2) of the grid portion 2A. 2 (upper right corner in FIG. 2), bent 90 ° (90 ° to the left in FIG. 2) and extended (sign 2s), and branched to each core 2 in the longitudinal direction of the lattice-shaped portion 2A. Yes. Then, the core 2 reaches the remaining one (left side in FIG. 2) light receiving element 5 through the lattice-like portion 2A.

The clad layer covering the inverted U-shaped bent portion 2r and the 90 ° bent portion 2s of the core 2 may be the same as in the above embodiments. Thereby, the bending radius of the inverted U-shaped bent portion 2r and the 90 ° bent portion 2s can be reduced, and the position sensor can be saved in space.

Further, in each of the above embodiments, the cross-sectional structure of the optical waveguide W is shown in FIG. 1B, but may be other, for example, as shown in FIG. It is good also as a thing of the structure which turned upside down what is shown in. That is, in the optical waveguide W, the core 2 is embedded in the surface portion of the sheet-like underclad layer 1, and the surface of the underclad layer 1 and the top surface of the core 2 are formed flush with each other. A sheet-like over clad layer 3 is formed in a state where the surface of the clad layer 1 and the top surface of the core 2 are covered. The clad layer that covers the bent portion of the core at the outer peripheral portion of the core pattern member may be the same as in the above embodiments.

Further, in each of the above-described embodiments, each crossing portion of the core 2 of the lattice-like portion 2A is usually formed in a state in which all four intersecting directions are continuous as shown in an enlarged plan view in FIG. Others are acceptable. For example, as shown in FIG. 4B, only one intersecting direction may be divided by the gap G and discontinuous. The gap G is formed of a material for forming the under cladding layer 1 or the over cladding layer 3. The width d of the gap G exceeds 0 (zero), and is usually set to 20 μm or less. Similarly, as shown in FIGS. 4C and 4D, two intersecting directions [FIG. 4C is two opposing directions, and FIG. 4D is two adjacent directions] are discontinuous. As shown in FIG. 4 (e), the three intersecting directions may be discontinuous, or as shown in FIG. 4 (f), all the four intersecting directions may be discontinuous. It may be discontinuous. Furthermore, a lattice shape having two or more kinds of intersections among the intersections shown in FIGS. 4 (a) to 4 (f) may be used. That is, in the present invention, the “lattice shape” formed by the plurality of linear cores 2 means that a part or all of the intersections are formed as described above.

In particular, as shown in FIGS. 4B to 4F, if at least one intersecting direction is discontinuous, the light crossing loss can be reduced. That is, as shown in FIG. 5 (a), in an intersection where all four intersecting directions are continuous, if one of the intersecting directions [upward in FIG. 5 (a)] is noted, the light incident on the intersection 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 the incident angle at the wall surface 2a is smaller than the critical angle, and thus passes through the core 2 [FIG. a) (See the two-dot chain line arrow). Such transmission of light also occurs in the direction opposite to the above (downward in FIG. 5A). On the other hand, as shown in FIG. 5B, when the intersecting one direction [upward in FIG. 5B] is discontinuous by the gap G, the interface between the gap G and the core 2 is Part of the light formed and transmitted through the core 2 in FIG. 5 (a) is reflected at the interface without passing through the interface because the incident angle at the interface is larger than the critical angle. Continue to advance the core 2 (see the two-dot chain arrow in FIG. 5B). From this, as described above, if at least one intersecting direction is discontinuous, the light crossing loss can be reduced. As a result, it is possible to increase the detection sensitivity of the pressed position by the pen tip or the like.

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

[Example 1]
[Formation material of under clad layer and over clad layer]
Component a: 60 parts by weight of an epoxy resin (Mitsubishi Chemical Corporation YL7410).
Component b: 40 parts by weight of epoxy resin (manufactured by Daicel, EHPE3150).
Component c: 4 parts by weight of a photoacid generator (manufactured by Sun Apro, CPI101A).
By mixing these components a to c, materials for forming the under cladding layer and the over cladding layer were prepared.

[Core forming material]
Component d: 90 parts by weight of an epoxy resin (manufactured by Daicel Corporation, EHPE3150).
Component e: 10 parts by weight of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, Epicoat 1002).
Component f: 1 part by weight of a photoacid generator (manufactured by ADEKA, SP170).
Component g: 50 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries, Ltd., solvent).
A core forming material was prepared by mixing these components d to g.

[Production of optical waveguide]
First, a substantially rectangular undercladding layer was formed by spin coating using the undercladding layer forming material. The thickness of this under cladding layer was 25 μm. The elastic modulus was 240 MPa and the refractive index was 1.50. The elastic modulus was measured using a viscoelasticity measuring device (TA instruments Japan Inc., RSA3).

Next, a sheet-like core pattern member having a lattice-shaped portion composed of a plurality of linear cores and an outer peripheral portion is formed on the surface of the under-cladding layer by the photolithography method using the core forming material. [See FIG. 1 (a)]. In the outer peripheral portion of the core pattern member, the two arc-shaped portions that are the branched portions of the core connected to the light emitting element have a bending radius of 5 mm. The size of the grid portion (input area) was 210 mm long × 297 mm wide. The width of the core was 100 μm, the thickness was 50 μm, and the width of the gap between adjacent parallel linear cores in the lattice portion was 500 μm. The elastic modulus was 1.58 GPa and the refractive index was 1.51.

Next, an over clad layer is formed on the surface of the under clad layer by a photolithography method on the surface of the under clad layer so as to cover the core pattern member excluding the two arc-shaped portions of the core. Formed. The thickness of this over clad layer (thickness from the surface of the core) was 40 μm. The two arc-shaped portions of the core were exposed [covered with air clad (refractive index 1.00)]. The elastic modulus was 240 MPa and the refractive index was 1.50. In this way, a substantially rectangular sheet-shaped optical waveguide was produced.

[Production of position sensor]
A light emitting element (Optowell, XH85-S0603-2s) is connected to one end face of the core of the outer periphery of the core pattern member, and a light receiving element (Hamamatsu Photonics, s10226) is connected to the other end face of the core. did.

[Example 2]
In Example 1, the air clad portion was formed of the second over clad layer having a refractive index (1.48) lower than the refractive index (1.50) of the over clad layer. The material for forming the second overcladding layer is shown below. The other parts were the same as in Example 1 above.

[Material for forming second overclad layer]
Component h: 80 parts by weight of an epoxy resin (Mitsubishi Chemical Corporation, YL7410).
Component i: 20 weight part of epoxy resins (Daicel, 2021P).
Component j: 4 parts by weight of a photoacid generator (manufactured by San Apro, CPI101A).
A material for forming the second overcladding layer was prepared by mixing these components h to j.

[Comparative Example]
In Example 1 described above, the bending radius of the two arc-shaped portions, which are the branched portions of the core connected to the light emitting element, was 10 mm. Then, the surface of the under cladding layer was covered with the over cladding layer so as to cover the entire core pattern member (see FIG. 6). The other parts were the same as in Example 1 above.

In each of Examples 1 and 2 and the comparative example, proper light propagation was performed and the pressed position could be detected. However, in the comparative example, when the bending radius of the two arc-shaped portions of the core is smaller than 10 mm, proper light propagation is not performed, and the pressed position cannot be detected properly. The cause was found to be leakage of light at the two arc-shaped portions of the core.

From the above results, it can be seen that the position sensors of Examples 1 and 2 can reduce the bending radius of the two arc-shaped portions of the core and can save space as compared with the position sensor of the comparative example.

In general, the larger the difference in refractive index between the core and the clad, the smaller the bending radius of the core. However, although the difference in refractive index is smaller in Example 2 (difference in refractive index 0.03) than in Example 1 (difference in refractive index 0.51), the bending radius may be 5 mm. For example, it can be bent. That is, in the first embodiment, it is possible to further reduce the bending radius.

Further, in Examples 1 and 2, one light emitting element and one light receiving element are used, but as shown in FIG. 2, even when two elements are used, the same tendency as in Examples 1 and 2 is shown. Results were obtained.

Further, in the first and second embodiments, the optical waveguide is shown in a sectional view in FIG. 1B. However, the optical waveguide is shown in the sectional view in FIG. 3 as in the first and second embodiments. The result which shows the tendency of was obtained.

In the above embodiments, specific forms in the present invention have been described. However, the above embodiments are merely examples and are not construed as limiting. Various modifications apparent to those skilled in the art are contemplated to be within the scope of this invention.

The position sensor of the present invention can be used for space saving.

W optical waveguide 1 under clad layer 2 core 2A lattice portion 2B outer

peripheral portion

2p, 2q arc-shaped portion 3 over clad layer

Claims

A grid-like portion having a plurality of grids in which linear cores are arranged vertically and horizontally and a grid-like portion extending from the core of the grid-like portion and bent along the outer periphery of the grid-like portion A sheet-like core pattern member provided with an outer peripheral portion, a sheet-like optical waveguide coated with a clad layer, and
A position sensor comprising a light emitting element and a light receiving element connected to the core of the optical waveguide,
The refractive index of the cladding layer covering the bent portion of the core of the outer peripheral portion is smaller than the refractive index of the cladding layer covering the core of the other portion in order to reduce leakage of light propagating through the bent portion. Is set low,
A position sensor characterized in that a surface portion of a clad layer corresponding to a lattice-like portion of the core pattern member is used as an input region, and a pressing position in the input region is specified by a light propagation amount of a core changed by the pressing.