WO2016031539A1

WO2016031539A1 - Position sensor

Info

Publication number: WO2016031539A1
Application number: PCT/JP2015/072594
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: 2014-08-25
Filing date: 2015-08-10
Publication date: 2016-03-03
Also published as: TW201610790A; JP2016045772A

Abstract

This invention provides a position sensor that makes it possible to save space and improve the sensitivity with which pressure positions are detected. Said position sensor contains a sheet-shaped optical waveguide W, and said optical waveguide W comprises a sheet-shaped core-pattern member sandwiched between a lower cladding layer 1 and an upper cladding layer 3. The core-pattern member has a grid section 2A and periphery sections 2B. The grid section 2A comprises a plurality of linear cores 2, and the periphery sections 2B extend from the cores 2 in the grid section 2A and are laid out along the perimeter of the grid section 2A. The section of the surface of the upper cladding layer 3 corresponding to the grid section 2A of the core-pattern member serves as an input region 3A, and at least parts of edge sections F of the optical waveguide W, which correspond to the periphery sections 2B of the core-pattern member, are folded over to the back of the optical waveguide W. The indices of refraction of the upper cladding layer 3, the lower cladding layer 1, and the core 2 are set such that the core 2 has the highest index of refraction, followed by the lower cladding layer 1 and then the upper cladding layer 3.

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. 8 (a), this has a rectangular sheet-shaped optical waveguide W1 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-shaped portion 12A formed by arranging a plurality of linear optical path cores 12 vertically and horizontally, and extends from the core 12 of the lattice-shaped portion 12A to the outer periphery of the lattice-shaped portion 12A. The outer peripheral part 12B arrange | positioned in the state along is provided. The elastic modulus of the core 12 is set larger than the elastic modulus of the under cladding layer 11 and the elastic modulus of the over cladding layer 13. A light emitting element 14 is connected to one end face of the core 12 of the outer peripheral portion 12B of the core pattern member, and a light receiving element 15 is connected to the other end face of the core 12. The light emitted from the light emitting element 14 passes through the core 12 from the outer peripheral portion 12B connected to the light emitting element 14 through the lattice portion 12A and the outer peripheral portion 12B on the opposite side. It is designed to receive light. Further, the surface portion of the over clad layer 13 corresponding to the lattice-like portion 12A of the core pattern member [rectangular portion indicated by a one-dot chain line in the center of FIG. 8A] is an input region 13A of the position sensor.

When inputting, as shown in FIG. 8B, the input area corresponding to the grid-like portion 12A in a state where the position sensor is placed on a flat table 30 such as a table, for example. Pressing 13A with the pen point 10 for input is performed. Thereby, in the cross section in the pressing direction, the over-cladding layer 13 and the under-cladding layer 11 having a small elastic modulus are deformed so as to be crushed, and the core 12 having a large elastic modulus is hardly crushed (while maintaining the cross-sectional area). ), Bent along the pen tip 10 so as to sink into the underclad layer 11. Then, the light propagating through the core 12 leaks to the under cladding layer 11 outside the bent core 12 (refer to the two-dot chain line arrow in FIG. 8B). Therefore, in the core 12 of the pressing portion, the light receiving level at the light receiving element 15 decreases, and the pressing position can be detected from the decrease in the light receiving level.

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 light propagating through the core is difficult to leak into the under-cladding layer and the over-cladding layer. It has become. From the viewpoint of making the light propagation property as an optical waveguide uniform by making the light leakage from the core equal to both the under-cladding layer and the over-cladding layer, the refractive index of the under-cladding layer It is common technical knowledge that the refractive index of the overcladding layer is the same.

Japanese Patent No. 5513656

The position sensor is required to increase the detection sensitivity of the pressed position.

The position sensor includes a peripheral portion (frame portion) F1 of the optical waveguide W1 in which the outer peripheral portion 12B of the core pattern member is sandwiched between the side edge portion of the under cladding layer 11 and the side edge portion of the over cladding layer 13. Have. That is, the position sensor requires a larger space than the input region 13A due to the presence of the peripheral edge portion F1 formed around the input region 13A. When the input area 13A of the position sensor is widened or the detection accuracy of the pressed position in the input area 13A is improved, it is necessary to increase the number of cores 12, and accordingly, the width of the peripheral portion F1. Need to be wide. For this reason, the position sensor requires a larger space. There is room for improvement in that respect.

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

In order to achieve the above object, the position sensor of the present invention has a lattice-shaped portion composed of a plurality of linear cores, and extends along the outer periphery of the lattice-shaped portion extending from the core of the lattice-shaped portion. A sheet-like optical waveguide sandwiched between an under-cladding layer and an over-cladding layer, and a light-emitting element connected to one end face of the core of the outer-peripheral portion; And a light receiving element connected to the other end face of the core of the outer peripheral portion, wherein at least a part of the peripheral portion of the optical waveguide corresponding to the outer peripheral portion of the core pattern member is the under cladding layer With the over clad layer on the outside and bent on the back side of the optical waveguide, and has the following configurations (A) and (B). The emitted light is received by the light receiving element through the core of the optical waveguide, and the surface portion of the over clad layer corresponding to the lattice portion of the core pattern member is used as an input region, and the pressed position in the input region Is determined by the amount of light propagation of the core changed by the pressing.
(A) 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, and in the pressed state of the surface of the over cladding layer, A configuration in which the deformation rate is smaller than the deformation rate of the cross section of the over clad layer and the under clad layer, and the core of the pressing portion is bent so as to sink into the under clad layer.
(B) The difference between the refractive index of the core and the refractive index of the over cladding layer is set to be larger than the difference between the refractive index of the core and the refractive index of the under cladding layer. Light propagating through the core is likely to leak into the undercladding layer, and the change in the amount of light propagation of the core due to pressing increases. A configuration in which propagating light is difficult to leak into the overcladding layer.

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

The inventors of the present invention have repeated research focusing on light leakage from the core of the pressed portion in order to increase the detection sensitivity of the pressed position. That is, as described in the background art above, in the optical waveguide in which 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, the core of the pressing portion is almost crushed. The light that propagates through the core is leaked to the under-cladding layer outside the bent core. Accordingly, the present inventors have conceived of increasing the detection sensitivity of the pressed position by making it easier for light to leak from the core of the pressed portion and increasing the change in the amount of light propagation of the core due to the press in the course of the above research. did. Therefore, the difference between the refractive index of the core and the refractive index of the under cladding layer and the over cladding layer (the refractive index of the under cladding layer and the refractive index of the over cladding layer are the same) is reduced.

However, in order to save space, if at least part of the peripheral portion of the optical waveguide is bent to the back side of the optical waveguide with the under cladding layer inside and the over cladding layer outside, this time, Light easily leaks from the bent portion (curved surface) core to the outer overcladding layer. Therefore, the light propagation amount of the core is reduced, and it is difficult to receive the propagation light by the light receiving element.

Conversely, if the difference in refractive index is increased and light does not easily leak from the folded core, light will also hardly leak from the pressed core, and the detection sensitivity of the pressed position will be reduced.

Therefore, the present inventors have continued research, focusing on the fact that light in the core leaks into the under cladding layer outside the bent core at the pressed portion and leaks into the outer over cladding layer at the bent portion. . And the conventional technical common sense was broken, and the difference between the refractive index of the core and the refractive index of the over cladding layer was set to be larger than the difference between the refractive index of the core and the refractive index of the under cladding layer. . Then, in the pressed portion, the light in the core easily leaks to the under cladding layer, and the change in the amount of light propagation of the core due to pressing increases, and in the bent portion, the light in the core leaks to the over cladding layer. I found it difficult. That is, the difference in refractive index can increase the detection sensitivity of the pressed position, and it can be found that space saving can be achieved by bending at least a part of the peripheral portion of the optical waveguide to the back side of the optical waveguide, The present invention has been reached.

In the position sensor of the present invention, the core is patterned into a lattice-shaped portion and an outer peripheral portion arranged in a state along the outer periphery, and an overcladding layer corresponding to the lattice-shaped portion of the core pattern member is formed. The surface portion is the input area. Further, at least a part of the peripheral portion of the optical waveguide corresponding to the outer peripheral portion of the core pattern member is bent to the back side of the optical waveguide with the under cladding layer on the inside and the over cladding layer on the outside. . Further, 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. The difference between the refractive index of the core and the refractive index of the over cladding layer is set larger than the difference between the refractive index of the core and the refractive index of the under cladding layer. As a result, light propagating in the core easily leaks to the under cladding layer at the pressing portion, and the change in the amount of light propagation of the core due to pressing increases, and at the bent portion, the light propagates through the core. It is difficult for light to leak into the overcladding layer. Therefore, the position sensor of the present invention can improve the detection sensitivity of the pressed position, and can save space by the amount of the bent peripheral portion.

Particularly, when the tip of the bent portion is positioned on the back side of the optical waveguide corresponding to the input region, the thickness of the position sensor can be reduced.

It is a top view showing typically one embodiment of a position sensor of the present invention. (A) is a top view which shows typically the preparation process of the said position sensor, (b) is an expanded sectional view of the center part, (c) is an expanded sectional view of the side edge part is there. It is an expanded sectional view showing typically the state of the above-mentioned position sensor pressed by the pen tip. It is an expanded sectional view of the side edge part which shows other embodiments of the position sensor of the present invention 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. (A) is a top view which shows typically the conventional position sensor, (b) is an expanded sectional view which shows typically the state of the conventional position sensor pressed with the pen tip.

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 of this embodiment has three peripheral portions F of the substantially rectangular sheet-shaped optical waveguide W shown in a plan view in FIG. 2A (left and right sides and lower side in FIG. 2A). The optical waveguide W is bent on the back side. Thereby, space saving of the position sensor is achieved. In FIG. 2A, the three portions indicated by the two-dot chain line of the peripheral portion F are portions that are hidden behind the optical waveguide W by the bending and are not visible in plan view.

That is, the position sensor according to this embodiment includes a substantially rectangular sheet-shaped optical waveguide W and two light emitting elements disposed at two adjacent corners of the optical waveguide W, as shown in FIG. An element 4 and two light receiving elements 5 disposed at the remaining two corners of the optical waveguide W are provided. A rectangular portion at the center of the surface of the optical waveguide W [a quadrangular portion indicated by a one-dot chain line in FIG. 2A] is an input region 3A, and FIG. 2B (enlarged sectional view of the central portion of the position sensor). As shown in FIG. 3, an electric circuit board E is provided on the back surface portion of the optical waveguide W corresponding to the input region 3A. Of the four peripheral portions (frame portions) F of the optical waveguide W around the input region 3A, the peripheral portions F at the three locations (the left and right sides and the lower side in FIG. 2A) are shown in FIG. 2 (c) (enlarged sectional view of the side edge portion of the position sensor), it is bent. The bent front end of the peripheral portion F is brought into contact with an electric circuit forming surface of the electric circuit board E (a surface opposite to the optical waveguide W: a lower surface in FIG. 2C), and the light emitting element 4 and the light receiving element 5 are mounted on the electric circuit forming surface of the electric circuit board E. In this embodiment, the peripheral portion F at one portion that is not bent (the upper side in FIGS. 1 and 2A) is formed narrow in advance so that it does not need to be bent.

More specifically, the optical waveguide W includes a lattice-shaped portion 2A composed of a plurality of linear optical path cores 2 on the surface of the substantially quadrilateral sheet-like underclad layer 1, and the core 2 of the lattice-shaped portion 2A. A sheet-like core pattern member is formed which includes an outer peripheral portion 2B extending from the outer periphery of the lattice-shaped portion 2A and covering the core pattern member. An over clad layer 3 is formed on the surface of the layer 1. And the surface part of the over clad layer 3 corresponding to the lattice-like part 2A of the core pattern member is the input region 3A. Further, a portion where the outer peripheral portion 2B of the core pattern member is sandwiched between the side edge portion of the under cladding layer 1 and the side edge portion of the over cladding layer 3 is a peripheral portion (frame portion) F of the optical waveguide W. Yes. In FIG. 1 and FIG. 2A, 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 and FIG. 2A, the number of cores 2 is omitted. The arrows in FIGS. 1 and 2 (a) indicate the light traveling direction.

In the 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. For example, the elastic modulus of the core 2 is set in a range of 1 GPa or more and 10 GPa or less, and the elastic modulus of the over clad layer 3 is set in a range of 0.1 GPa or more and less than 10 GPa. The elastic modulus of 1 is preferably set in the range of 0.1 MPa to 1 GPa.

Due to the magnitude relationship of the elastic modulus, when inputting, for example, characters or the like are written in the input area 3A directly or through a resin film, paper or the like, for example, with an input pen, as described in the background art above. 3, in the cross section in the direction of pressing by the pen tip 10, the over clad layer 3 and the under clad layer 1 having a low elastic modulus are deformed so as to be crushed, and the core 2 having a high elastic modulus. Bends so as to sink into the undercladding layer 1 along the nib 10 with almost no collapse (while maintaining the cross-sectional area). Then, the light propagating through the core 2 leaks to the under cladding layer 1 outside the bent core 2 (see the two-dot chain line arrow in FIG. 3). For this reason, in the core 2 at the pressing portion, the light receiving level at the light receiving element 5 decreases, and the pressing position can be detected from the decrease in the light receiving level.

Here, in this embodiment, the refractive index is set so as to increase in the order of the over cladding layer 3, the under cladding layer 1, and the core 2. That is, the difference between the refractive index of the core 2 and the refractive index of the over cladding layer 3 is set to be larger than the difference between the refractive index of the core 2 and the refractive index of the under cladding layer 1. For example, the refractive index of the core 2 is set in the range of 1.002 to 1.700, the refractive index of the over clad layer 3 is set in the range of 1.000 to 1.698, and The refractive index of the cladding layer 1 is set within a range of 1.001 to 1.699. The difference between the refractive index of the core 2 and the refractive index of the over clad layer 3 is preferably set in the range of 0.005 to 0.6.

Due to the difference in refractive index, light propagating through the core 2 is likely to leak into the under cladding layer 1 in the pressed portion, and the light receiving level at the light receiving element 5 is further reduced. It becomes clearer and the detection sensitivity of the pressed position can be increased.

Furthermore, due to the difference in refractive index, light propagating through the core 2 is difficult to leak into the outer overcladding layer 3 at the bent portion (curved surface portion) of the optical waveguide W. Therefore, the light from the light emitting element 4 can be reliably propagated to the lattice-like portion 2A of the core pattern member, and the light propagating through the lattice-like portion 2A can be reliably made to reach the light receiving element 5. Thereby, a press position can be detected appropriately.

Further, in this embodiment, one light emitting element 4 is connected to one end face of the core 2 of the outer peripheral portion 2B where the longitudinal core 2 of the lattice-like portion 2A of the core pattern member is extended, and the core One light-receiving element 5 is connected to the other end face of 2, and another light-emitting element 4 is attached to one end face of the core 2 of the outer peripheral part 2 </ b> B in which the transverse core 2 of the lattice-like part 2 </ b> A extends. Is connected, and another light receiving element 5 is connected to the other end face of the core 2. The light emitted from the light emitting element 4 passes through the core 2 through the outer peripheral part 2B on the opposite side from the outer peripheral part 2B connected to the light emitting element 4 through the lattice part 2A. It is designed to receive light.

In this way, by connecting the light emitting element 4 and the light receiving element 5 in the vertical direction and the horizontal direction (XY direction) of the grid-like portion 2A, the two directions can be controlled separately, and the input region The detection accuracy of the pressed position (XY coordinate) in 3A can be improved. Furthermore, as described above, since the light emitting element 4 or the light receiving element 5 is disposed at each corner of the substantially rectangular sheet-shaped optical waveguide W, the light from the light emitting element 4 to the lattice-shaped portion 2A. The propagation distance and the light propagation distance from the lattice-like portion 2A to the light receiving element 5 can be shortened, and the light propagation efficiency can be improved.

As described above [see FIG. 2 (c)], the electric circuit board E is provided on the back surface (the surface opposite to the core formation surface) of the under cladding layer 1 of the optical waveguide W corresponding to the input region 3A. ) Part. The tip of the peripheral portion F of the bent optical waveguide W is in contact with the electric circuit forming surface of the electric circuit board E (the surface opposite to the under cladding layer 1; the lower surface in FIG. 2C). The light emitting element 4 and the light receiving element 5 are mounted on the electric circuit forming surface of the electric circuit board E. Here, the thickness of the electric circuit board E is set in a range of 1 to 10 mm, for example, and the bending radius (inner diameter) R of the bent portion is set in a range of 0.5 to 5 mm, for example. . If the bending radius R is too small, the light propagation efficiency at the bent portion tends to be reduced. If it is too large, the protruding width (frame width) T of the bent portion protruding around the input region 3A is large. Therefore, the effect of space saving of the position sensor tends to be reduced.

In the manufacturing method of the position sensor, first, the optical waveguide W and the electric circuit board E are individually manufactured. Next, the back surface portion of the under cladding layer 1 of the optical waveguide W corresponding to the input region 3A is brought into contact with the surface of the electrical circuit board E opposite to the electrical circuit formation surface. Next, the light emitting element 4 and the light receiving element 5 are connected to the end face of the core 2 of the optical waveguide W. The peripheral portion F of the optical waveguide W is bent at a right angle with respect to the core 2 of the peripheral portion F, and the tip of the bent peripheral portion F is brought into contact with the electric circuit forming surface of the electric circuit board E. The light emitting element 4 and the light receiving element 5 are mounted on the electric circuit forming surface. In this way, the position sensor can be obtained.

Examples of the material for forming the under cladding layer 1, the core 2 and the over cladding layer 3 include a photosensitive resin, a thermosetting resin, and the like, and the optical waveguide W can be manufactured by a manufacturing method corresponding to the forming material. . The elastic modulus and refractive index can be adjusted by, for example, selecting the type of each forming material and adjusting the composition ratio. The thickness of each layer 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.

FIG. 4 is an enlarged cross-sectional view showing a side edge portion of another embodiment of the position sensor of the present invention. In this embodiment, in the above-described embodiment shown in FIGS. 1 and 2A to 2C, the bent portion of the peripheral portion F of the optical waveguide W is bent 90 ° to the back side of the optical waveguide W. It has become a thing. Correspondingly, the electric circuit board E is also bent by 90 °. The other parts are the same as those of the above-described embodiment shown in FIGS. 1 and 2A to 2C, and the same reference numerals are given to the same parts.

In this embodiment as well, as in the above-described embodiment shown in FIGS. 1 and 2A to 2C, it is possible to increase the detection sensitivity of the pressed position, and to save space in the plan view of the position sensor. Can be planned. Further, the position sensor of this embodiment can be installed at a corner of a desk or the like along the inside of the portion bent by 90 °.

In each of the above embodiments, the cross-sectional structure of the optical waveguide W is shown in FIG. 2B, but may be other, for example, as shown in the cross-sectional view of 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.

Further, in each of the above embodiments, three of the four peripheral portions F of the optical waveguide W are bent, but may be other, for example, all four may be bent, or two may be bent. It is good or you may bend only one place.

Furthermore, in each of the above-described embodiments, two light emitting elements 4 and two light receiving elements 5 are used. However, other light emitting elements 4 and light receiving elements 5 may be used. For example, one light emitting element 4 or three or more light receiving elements 5 may be used. In the above embodiment, the light emitting element 4 or the light receiving element 5 is disposed at each corner of the substantially rectangular sheet-shaped optical waveguide W. However, for example, all of the light emitting element 4 and the light receiving element 5 are provided. Alternatively, they may be disposed at the same end edge of the substantially rectangular sheet-shaped optical waveguide W.

Further, in each of the above embodiments, each of the intersecting portions of the core 2 of the lattice-like portion is normally formed in a state in which all of the four intersecting directions are continuous as shown in an enlarged plan view in FIG. Others are acceptable. For example, as shown in FIG. 6B, 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. 6C and 6D, two intersecting directions (two directions facing each other in FIG. 6C and two adjacent directions in FIG. 6D) are discontinuous. As shown in FIG. 6 (e), the three intersecting directions may be discontinuous, or as shown in FIG. 6 (f), all the four intersecting directions may be discontinuous. It may be discontinuous. Furthermore, a lattice shape including two or more kinds of intersections among the intersections shown in FIGS. 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. 6B to 6F, if at least one crossing direction is discontinuous, the light crossing loss can be reduced. That is, as shown in FIG. 7 (a), in an intersection where all four intersecting directions are continuous, if one of the intersecting directions (upward in FIG. 7 (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 is smaller than the critical angle, and thus passes through the core 2 [FIG. )) Such transmission of light also occurs in the direction opposite to the above (downward in FIG. 7A). On the other hand, as shown in FIG. 7B, when one intersecting direction (the upward direction in FIG. 7B) 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. 7A is reflected at the interface without transmitting 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. 7B). 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 over clad layer]
Component a: 50 parts by weight of an epoxy resin (Mitsubishi Chemical Corporation, YL7410).
Component b: 50 parts by weight of epoxy resin (manufactured by Daicel, EHPE3150).
Component c: 1 part by weight of a photoacid generator (manufactured by Sun Apro, CPI101A).
By mixing these components a to c, an over clad layer forming material was prepared.

[Core forming material]
Component d: 100 parts by weight of epoxy resin (manufactured by Daicel, EHPE3150).
Component e: 1 part by weight of a photoacid generator (manufactured by ADEKA, SP170).
Component f: 50 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries, Ltd., solvent).
By mixing these components d to f, a core forming material was prepared.

[Formation material of under cladding layer]
Component g: 60 parts by weight of an epoxy resin (Mitsubishi Chemical Corporation, YL7410).
Ingredient h: 40 weight part of epoxy resins (the product made by Daicel, EHPE3150).
Component i: 1 part by weight of a photoacid generator (manufactured by San Apro, CPI101A).
By mixing these components g to i, a material for forming the underclad layer was prepared.

[Production of optical waveguide]
First, an under clad layer was formed by spin coating using the under clad layer forming material. The thickness of the under cladding layer was 50 μm. The elastic modulus was 0.25 GPa and the refractive index was 1.496. 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. did. 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 1.5 GPa and the refractive index was 1.506.

Next, an over clad layer was formed on the surface of the under clad layer by spin coating using the over clad layer forming material so as to cover the core pattern member. The thickness of the over clad layer (thickness from the core surface) was 25 μm. The elastic modulus was 0.25 GPa and the refractive index was 1.486. In this way, a sheet-like optical waveguide was produced.

[Production of position sensor]
Prepare an electric circuit board having the same dimensions as the input area, with an electric circuit formed on one side, and an underclad of an optical waveguide corresponding to the input area on the opposite side of the electric circuit forming surface of the electric circuit board The back side of the layer was brought into contact. Next, a light emitting element (Optowell, XH85-S0603-2s) is connected to one end face of the outer peripheral core, and a light receiving element (Hamamatsu Photonics, s10226) is connected to the other end face of the outer peripheral core. Connected. Then, the peripheral portions of the three portions of the optical waveguide were bent and brought into contact with the electric circuit forming surface of the electric circuit board, and the light emitting element and the light receiving element were mounted on the electric circuit forming surface. In the bending, the protruding width of the bent portion protruding around the input region was 10 mm at two positions on both sides, and 5 mm at one position between them, and the bending radius was 2 mm. In this case, the widths of the peripheral portions of the three bent portions were 47.5 mm and 35.5 mm at two locations on both sides, and 60.0 mm at one location therebetween.

[Examples 2 to 4 and Comparative Examples 1 to 4]
In Example 1 above, by changing the type and composition ratio of each forming material of the optical waveguide, the elastic modulus and refractive index were changed as shown in Table 1 below, and these were changed to Examples 2 to 4 and Comparative Example 1 respectively. ~ 4.

[Pressing position detection sensitivity (attenuation rate)]
The tip of the ballpoint pen (diameter 0.7 mm) was pressed against the surface of the input area of each position sensor with a load of 0.25 N. And the light reception level (light reception intensity | strength) in the said light receiving element was measured by the case where the said load was not applied, and the case where it applied, and the attenuation factor was computed according to following formula (1). The results are shown in Table 1 below. It shows that the detection sensitivity of the pressed position is higher as the attenuation rate is larger.

[Bending loss]
A linear optical waveguide was produced in the same manner as described above using the respective forming materials of Examples 1 to 4 and Comparative Examples 1 to 4. Then, the central portion in the longitudinal direction of the linear optical waveguide is wound once around a rod having a radius of 2 mm, and in this state, light emitted from the light emitting element is incident from one end of the optical waveguide, and the other end The light emitted from was received by the light receiving element. And loss value ((alpha)) was computed according to the following formula | equation (2) from the emitted light intensity (A) of the said light emitting element, and the received light intensity (B) in the said light receiving element. Further, the light receiving intensity (C) was measured in the same manner as described above with the linear optical waveguide being linear, and the loss value (β) was calculated according to the following equation (3). And bending loss (D) was computed according to following formula (4). The results are shown in Table 1 below.

From the results of Table 1 above, the difference between the refractive index of the core and the refractive index of the over cladding layer is set to be larger than the difference between the refractive index of the core and the refractive index of the under cladding layer. 4 shows that the detection sensitivity of the pressed position is high and the bending loss is small. On the other hand, in Comparative Examples 1 to 4 where the difference in refractive index is not set as described above, the detection sensitivity of the pressed position is low, the bending loss is high, or both. Recognize.

In the first to fourth embodiments, the optical waveguide is shown in a sectional view in FIG. 2B. However, the optical waveguide is shown in the sectional view in FIG. 5 as in the first to fourth 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 to improve the detection sensitivity of the pressed position and save space.

W Optical waveguide F Peripheral part 1 Under clad layer 2 Core 2A Grid-like part 2B Peripheral part 3 Over clad layer 3A Input region

Claims

A sheet-like core pattern member comprising a lattice-shaped portion composed of a plurality of linear cores and an outer peripheral portion that extends from the core of the lattice-shaped portion and is arranged along the outer periphery of the lattice-shaped portion A sheet-like optical waveguide sandwiched between the under cladding layer and the over cladding layer,
A light emitting element connected to one end face of the core of the outer peripheral portion;
A position sensor comprising a light receiving element connected to the other end surface of the core of the outer peripheral portion,
At least a part of the peripheral portion of the optical waveguide corresponding to the outer peripheral portion of the core pattern member is bent to the back side of the optical waveguide with the under cladding layer on the inside and the over cladding layer on the outside. ,
And it has the structure of the following (A) and (B),
The light emitted from the light emitting element is received by the light receiving element through the core of the optical waveguide, and the surface portion of the over clad layer corresponding to the lattice portion of the core pattern member is used as an input region. A position sensor characterized in that a pressing position in a region is specified by a light propagation amount of a core changed by the pressing.
(A) 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, and in the pressed state of the surface of the over cladding layer, A configuration in which the deformation rate is smaller than the deformation rate of the cross section of the over clad layer and the under clad layer, and the core of the pressing portion is bent so as to sink into the under clad layer.
(B) The difference between the refractive index of the core and the refractive index of the over cladding layer is set to be larger than the difference between the refractive index of the core and the refractive index of the under cladding layer. Light propagating through the core is likely to leak into the undercladding layer, and the change in the amount of light propagation of the core due to pressing increases. A configuration in which propagating light is difficult to leak into the overcladding layer.
The position sensor according to claim 1, wherein a tip of the bent portion is positioned on a back surface side of the optical waveguide corresponding to the input region.