WO2017043570A1 - Optical waveguide, and position sensor and optical circuit board using optical waveguide - Google Patents

Abstract

Provided are an optical waveguide capable of appropriate light propagation, and a position sensor and an optical circuit board using the optical waveguide. A core 32 of an optical waveguide W2 is partly formed into an S shape. In the S-shaped portion, a first curved line section S1 located on the upstream side in the light propagation direction is connected, via a straight line section having a length of 0-30 mm, to a second curved line section S2 which is located on the downstream side and of which the curving direction is opposite to that of the first curved line section S1. Further, either a width B1 of the exit of the first curved line section S1 or a width B2 of the entrance of the second curved line section is smaller than a width B0 of a portion of the core located on the upstream side of the S-shaped portion.

Description

Optical waveguide, position sensor using the same, and optical circuit board

The present invention relates to an optical waveguide, a position sensor that optically detects a pressing position using the optical waveguide, and an optical circuit board that propagates light with an optical element using the optical waveguide.

The present applicant has proposed a position sensor that optically detects a pressed position using an optical waveguide (see, for example, Patent Document 1). As shown in FIG. 17 (a), this has a rectangular sheet-shaped optical waveguide W10 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 formed by arranging a plurality of linear optical path cores 12 vertically and horizontally, and a state along one horizontal side and one vertical side of the outer periphery of the lattice portion 12A. The first outer peripheral core portion 12B arranged and the second outer peripheral core portion arranged along the other horizontal side and the other vertical side facing the one horizontal side and the one vertical side via the lattice-like portion 12A 12C. The first outer peripheral core portion 12 </ b> B includes a single core 26, and the leading ends of the vertical and horizontal cores 12 of the lattice-shaped portion 12 </ b> A are branched from the single core 26. The second outer peripheral core portion 12C includes a core 27 extending from the rear end of each core 12 of the lattice portion 12A. In the position sensor, the light emitting element 14 is connected to the end face of the first outer peripheral core portion 12B of the core pattern member, and the light receiving element 15 is connected to the end face of the second outer peripheral core portion 12C.

In the position sensor using such an optical waveguide, the light emitted from the light emitting element 14 branches from the core 26 of the first outer peripheral core portion 12B to each core 12 of the lattice portion 12A, and the second outer peripheral core portion 12C. The light receiving element 15 receives light through each core 27. Then, the surface portion of the over clad layer 13 corresponding to the lattice portion 12A (rectangular portion indicated by a one-dot chain line in the center of FIG. 17A) is an input region 13A of the position sensor.

The input to the position sensor is performed by pressing the input area 13A with, for example, an input pen tip. Thereby, the core 12 of the pressed portion is deformed, and the light propagation amount of the core 12 is reduced. Therefore, in the core 12 of the pressing portion, the light receiving intensity of the light receiving element 15 is reduced, so that the pressing position can be detected. Using this position detection, it is possible to detect input of characters and the like.

On the other hand, in recent electronic devices and the like, an optical circuit board is adopted in addition to an electric circuit board as the amount of transmission information increases. An example is shown in FIG. In this device, the optical circuit board is laminated on the electric circuit board. That is, the electric circuit board 80 includes an insulating layer 81 and electric wirings 82 formed on the surface of the insulating layer 81. The optical circuit board 70 includes an optical waveguide W20 [first cladding layer 71, core (optical path) 72, second cladding layer, which is laminated on the back surface of the insulating layer 81 (the surface opposite to the surface on which the electrical wiring 82 is formed). 73] and optical elements (light emitting element 74 and light receiving element 75) mounted on portions of the surface of the insulating layer 81 (formation surface of the electrical wiring 82) corresponding to both ends of the optical waveguide W20. (For example, refer to Patent Document 2). In this optical circuit board 70, both end portions of the optical waveguide W20 are formed on an inclined surface inclined by 45 ° with respect to the axial direction of the core 72, and the portions of the core 72 located on the inclined surface are light reflecting surfaces 72a, 72a, 72b. Further, through holes 81a and 81b are formed in the portion of the insulating layer 81 corresponding to the light emitting element 74 and the light receiving element 75, and between the light emitting element 74 and the light reflecting surface 72a at one end and the light receiving element 75. The light L (indicated by a two-dot chain line) can propagate through the through holes 81a and 81b (optically connected) between the light reflecting surface 72b at the other end.

The light propagation in the optical circuit board 70 is performed as follows. First, the light L emitted from the light emitting element 74 passes through the through hole 81 a of the insulating layer 81, passes through one end portion (the right end portion in FIG. 18) of the first cladding layer 71, and passes through one end portion of the core 72. The light is reflected by the light reflecting surface 72 a (the optical path is converted by 90 °) and propagates in the core 72. Then, the light L propagating through the core 72 is reflected by the light reflecting surface 72b at the other end portion (left end portion in FIG. 18) of the core 72 (the optical path is converted by 90 °). The light is emitted through the end portion, passes through the through hole 81 b of the insulating layer 81, and then received by the light receiving element 75.

Note that an optical fiber may be used in place of the light receiving element 75 at the other end of the optical circuit board 70. Also in this case, light propagation is performed in the same manner as described above.

JP 2014-1973363 A JP 2014-29466 A

However, in some cases, the position sensor [see FIG. 17A] cannot accurately detect the pressed position. Therefore, as a result of the investigation of the cause by the present inventors, when the pressed position cannot be detected accurately, the light receiving intensity of the light receiving element 15 is low even when the input region 13A is not pressed. I found that there is a part.

In this way, even if the input region 13A is not pressed and there is a portion where the light receiving intensity of the light receiving element 15 is low, when a character or the like is input, the light received by the light receiving element 15 is also pressed by the input. Therefore, the pressed position cannot be detected accurately. In this respect, the position sensor using the optical waveguide has room for improvement.

Also, in the optical circuit board 70 (see FIG. 18), the light receiving intensity of the light at the light receiving element 75 may be lowered in some cases. When an optical fiber is used instead of the light receiving element 75, the amount of light propagation to the optical fiber may be reduced. In such a case, since proper light propagation (information transmission) cannot be performed, an electronic device incorporating the optical circuit board 70 does not operate properly.

The present invention has been made in view of such circumstances, and an object thereof is to provide an optical waveguide capable of appropriate light propagation, a position sensor using the optical waveguide, and an optical circuit board.

In order to achieve the above object, the present invention provides an optical waveguide comprising a linear core for an optical path and a clad layer that sandwiches the core from above and below, and the core partially transmits light. The first curved portion on the upstream side and the second curved portion on the downstream side bent in the opposite direction to the first curved portion are connected via a straight portion having a length of 0 (zero) mm or more and 30 mm or less. One of the width of the outlet of the first curved portion and the width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion. The optical waveguide is a first gist.

Further, the present invention is a lattice-shaped portion composed of a plurality of linear cores, and is positioned on one horizontal side and one vertical side of the outer peripheral portion of the lattice-shaped portion. A first outer peripheral core portion optically connected to the tip of each horizontal core, and the other horizontal side and the other vertical side respectively facing the one horizontal side and the one vertical side through the lattice-like portion; A sheet-like core pattern member including a second outer peripheral core portion extending along the rear end of each of the lattice-shaped portions and extending from the rear end of each vertical core and the rear end of each horizontal core, and the core pattern member A sheet-like optical waveguide having a sheet-like cladding layer sandwiching the substrate from above and below, a light emitting element connected to the end face of the first outer peripheral core portion of the optical waveguide, and an end face of the second outer peripheral core portion A position sensor including the second light receiving element, wherein the second sensor The portion of the optical waveguide corresponding to at least a part of the peripheral core portion is the optical waveguide according to the first aspect, and light emitted from the light emitting element is transmitted from the first outer peripheral core portion to the lattice-shaped portion and the first portion. 2 The light is received by the light receiving element through the outer peripheral core portion, and the surface portion of the position sensor corresponding to the lattice portion of the core pattern member is used as an input region, and the pressing position in the input region is changed by the pressing. The position sensor specified by the amount of light propagation is a second gist.

Furthermore, the third aspect of the present invention is an optical circuit board including the optical waveguide according to the first aspect and an optical member optically connected to the end of the core of the optical waveguide.

In the present invention, the S-shape is a portion in which the first curved portion and the second curved portion are connected via a straight portion having a length of 0 (zero) mm or more and 30 mm or less as described above. And also includes an inverted S-shape. In addition, if the length of the straight line portion between the first curved portion and the second curved portion is 0 (zero) mm, there is no straight portion, and the first curved portion and the second curved portion are directly connected. That is the meaning. And the said 1st curve part and the 2nd curve part are the meanings which include what is bent even a little.

In the optical circuit board according to the third aspect of the present invention, the optical member is responsible for light emission, light reception, light propagation, and the like. For example, an optical element that performs photoelectric conversion (light-emitting element, light-receiving element), light Examples thereof include an optical fiber responsible for propagation, an optical fiber connector used for connecting the optical fiber, and the like.

In order to make the light receiving intensity of the light receiving elements uniform in the position sensor in a state where the input area is not pressed in the position sensor, first, the prior art shown in FIG. In FIG. 5, the reason why a portion where the light receiving intensity of the light receiving element 15 is lowered is generated in a state where the input region 13A is not pressed is investigated. As a result, it was found that light leakage occurred in the S-shaped core portion of the second outer peripheral core portion 12C between the lattice-shaped portion 12A and the light receiving element 15, and this was the cause. Here, the light receiving element 15 connected to the end face of the second outer peripheral core portion 12C is arranged at the peripheral edge of the sheet-like optical waveguide W10. Depending on the arrangement position of the light receiving element 15, the light receiving element 15 is arranged. In the vicinity (the portion surrounded by the ellipse D0 in FIG. 17A), at least a part of the core 27 of the second outer peripheral core portion 12C may be partially formed in the S shape.

Therefore, the present inventors investigated the cause of light leakage at the S-shaped part of the core 27. In the process of the pursuit, it was found that the light L is biased toward the outer portion of the curve of the first curved portion S11 on the upstream side in the S-shaped portion [see FIG. 17B]. On the other hand, in the position sensor, as the width of the cores 12, 26, 27 increases, the amount of light propagation of the cores 12, 26, 27 increases, and the amount of decrease in the propagating light due to pressing of the input region 13A increases. Therefore, the detection of the pressed position is facilitated. Therefore, in the conventional position sensor, the widths of the cores 12, 26 and 27 are formed wide. Then, as shown in FIG. 17B, when the core 27 is wide in the S-shaped portion, the light L biased toward the outer portion of the bending of the first curved portion S11 on the upstream side as described above. (Indicated by a two-dot chain line) propagates to the second curved line portion S12 on the downstream side, and propagates in the vicinity of the entrance of the second curved line portion S12 so as to be biased toward the inside of the curve. Concentrate on the outer side surface of the bend of the part S12. Here, when the width of the core 27 is wide as described above, the light L reaching the side surface has an incident angle θ smaller than the critical angle. It has been found that it penetrates (is leaked from the core 27). That is, it has been found that the cause of the leakage of the light L at the S-shaped part is that the width of the core 27 is wide at the S-shaped part.

Also, it has been found that the optical circuit board has the same problem as the position sensor. That is, in the conventional optical circuit board, when the light receiving intensity of the light receiving element is low, the core is partially formed in the S shape, and light leakage occurs in the S shape portion. Is occurring. Even in the conventional optical circuit board, the wider the core width, the greater the amount of light propagation (the amount of information transmitted) of the core. Therefore, the core width is widened. It was found that the light L leaked at the S-shaped part [see FIG. 17 (b)].

Further, in the portion where the first curved portion and the second curved portion are connected via the straight portion, when the length of the straight portion is 30 mm or less, the light is transmitted in the second curved portion as described above. Turned out to leak. On the other hand, when the length of the straight part exceeds 30 mm, it has been found that there is almost no light leakage at the second curved part. That is, in this case, the light that is biased toward the outer portion of the curve of the first curved portion repeats reflection on the side surface of the straight portion because the straight portion is sufficiently long, and near the exit of the straight portion. The bias is eliminated. For this reason, even near the entrance of the second curved portion, there is almost no deviation of the light to the inside of the bend, and there is almost no concentrated light reaching the side surface outside the bend of the second curved portion. Thereby, there is almost no light leakage at the second curved portion.

The present inventors have obtained such knowledge and conceived of narrowing the core width of the second curved portion on the downstream side in the S-shaped portion, and the width of the outlet of the first curved portion. And one of the width | variety of the inlet_port | entrance of the said 2nd curve part was made narrower than the width | variety of the core part upstream from the said S-shaped part. As a result, in the second curved portion, the light that has reached the side surface outside the bend of the second curved portion has an incident angle larger than the critical angle, and most of the light is reflected on the side surface, thereby leaking light. I found out that it can be reduced. That is, in the position sensor, even if the core of the second outer peripheral core portion between the lattice-shaped portion and the light receiving element is partially formed in an S shape, the S shape portion is specified as described above. In the core of the second outer peripheral core portion, it was determined that the light reaches the light receiving element in a state where leakage of the propagating light is reduced. As a result, the inventors have found that the light receiving intensity of the light receiving element is equal in a state where the input region is not pressed, and have reached the present invention.

Also, the optical circuit board was able to solve the light leakage from the S-shaped part of the core in the same manner as the position sensor. That is, even if the core is partially formed in an S-shape in the optical circuit board, by setting the S-shaped portion to a specific width as described above, the S-shaped portion It was found that leakage of propagating light can be reduced. As a result, it has been found that a decrease in the light receiving intensity of light at the light receiving element or a decrease in the amount of light propagation to the optical fiber is suppressed, and the present invention has been achieved.

And not only in the optical waveguide used for the position sensor and the optical circuit board, but also in an optical waveguide for other uses such as an opto-electric hybrid board, the core is partially formed in the S shape, It has been found that light propagation is made more appropriate.

In the above position sensor, “the intensity of light received by the light receiving element is equal” not only includes complete equality, but is also an abbreviation that can be detected if the pressed position in the input area of the position sensor can be accurately detected. It is meant to include equality.

In the optical waveguide of the present invention, the core is partially formed in an S-shape, and the S-shaped portion includes the width of the outlet of the first curved portion on the upstream side and the inlet of the second curved portion on the downstream side. Is narrower than the width of the core portion on the upstream side of the S-shaped portion. Therefore, when the light propagating through the first curved portion reaches the outer side surface of the second curved portion, the incident angle becomes larger than the critical angle, most of which is reflected from the side surface, and light leakage occurs. Can be reduced. That is, the optical waveguide of the present invention can make light propagation in the core more appropriate.

In the position sensor of the present invention, a portion of the optical waveguide corresponding to at least a part of the second outer peripheral core portion between the lattice portion and the light receiving element is the optical waveguide of the present invention. Therefore, in the core of the optical waveguide portion, when the light propagating through the first curved portion reaches the outer side surface of the second curved portion, the incident angle becomes larger than the critical angle, most of which Reflected by the side surface, light leakage can be reduced. That is, in the core of the second outer peripheral core portion, light reception by the light receiving element is performed in a state in which leakage of propagating light is reduced and the light reaches the light receiving element and does not press the input region. The strength can be made uniform. Therefore, when the input area is pressed, it is possible to clarify the portion where the light receiving intensity of the light receiving element decreases. As a result, the position sensor of the present invention can accurately detect the pressed position in the input area.

In the optical circuit board of the present invention, the optical waveguide optically connected to the optical member is the optical waveguide of the present invention. Therefore, in the S-shaped portion of the core of the optical waveguide, the incident angle becomes larger than the critical angle when the light propagating through the first curved portion reaches the outer side surface of the second curved portion. Most of the light is reflected from the side surface, and light leakage can be reduced. That is, when the optical member receives light from the end of the core of the optical waveguide, the core of the optical waveguide can reduce the leakage of propagating light, thereby suppressing the decrease in the light receiving intensity of the optical member. can do. Then, by forming the S-shaped part in the core, the degree of freedom in the core layout design is improved, and the core can be designed in accordance with the optical member layout. In addition, proper operation of an electronic device or the like incorporating the optical circuit board of the present invention can be reliably realized.

In particular, the width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the inlet of the second curved portion (B2: unit μm) The radius of curvature (R2: unit mm) of the second curved portion, the refractive index (K1) of the core on which the S-shaped portion is formed, and the refractive index (K2) of the cladding layer covering the side surface of the core ) Satisfies the following formula (1), the amount of light leaking through the second curved portion can be further reduced in the optical waveguide of the present invention. Therefore, in the position sensor of the present invention, the light receiving intensity of the light at the light receiving element can be more equalized, and the accuracy of detecting the pressed position can be improved. The radius of curvature (R2) of the second curved portion is the radius of curvature of the center line in the width direction of the second curved portion.

Furthermore, the entrance width of the second curved portion (B2: unit μm), the radius of curvature of the second curved portion (R2: unit mm), and the refractive index of the core on which the S-shaped portion is formed ( When the relationship between K1) and the refractive index (K2) of the clad layer covering the side surface of the core satisfies the following equation (2), the second curved portion in the optical waveguide of the present invention , The amount of light leaking can be further reduced. Therefore, in the position sensor of the present invention, the light receiving intensity of the light at the light receiving element can be further equalized, and the accuracy of detecting the pressed position can be further improved.

The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion is the inlet of the first curved portion. The width of the straight line portion and the width of the second curved portion are constant in the length direction, respectively, and the width of the outlet of the first curved portion, Even when the width of the straight line portion is equal to the width of the second curved portion, the amount of light leaking can be reduced in the second curved portion, and the light propagation in the core can be more appropriately performed. can do. And in the position sensor of this invention, the light reception intensity | strength in a light receiving element can be equalized, and a press position can be detected correctly.

The width of the inlet of the second curved portion is narrower than the width of the core portion on the upstream side of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the first The widths of the two curved portions are respectively constant in the length direction, the width of the first curved portion is wider than the width of the second curved portion, the width of the straight portion, The width of the second curved portion is equal, and the inlet of the straight portion is the portion of the outlet of the first curved portion corresponding to the outside of the bend of the first curved portion in the width direction. Even in the case of the arrangement, in the second curved portion, the amount of light that propagates can be reduced, and light propagation in the core can be made more appropriate. And in the position sensor of this invention, the light reception intensity | strength in a light receiving element can be equalized, and a press position can be detected correctly.

The width of the inlet of the second curved portion is narrower than the width of the core portion on the upstream side of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the first The widths of the two curved portions are respectively constant in the length direction, the width of the first curved portion is wider than the width of the second curved portion, and the width of the first curved portion is , The width of the straight line portion is equal, and the inlet of the second curved portion is the portion of the outlet of the straight portion corresponding to the outside of the bend of the first curved portion in the width direction. Even in the case of the arrangement, in the second curved portion, the amount of light that propagates can be reduced, and light propagation in the core can be made more appropriate. And in the position sensor of this invention, the light reception intensity | strength in a light receiving element can be equalized, and a press position can be detected correctly.

In addition, the width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion and the width of the second curved portion are , Each of the first curved portion is constant in the length direction, the width of the first curved portion is wider than the width of the second curved portion, and the width of the inlet of the straight portion is the first curved portion. Even when the exit width of the straight line portion is equal to the width of the second curved portion, the amount of light leaking in the second curved portion can be reduced, Light propagation can be made more appropriate. And in the position sensor of this invention, the light reception intensity | strength in a light receiving element can be equalized, and a press position can be detected correctly.

The width of the inlet of the second curved portion is narrower than the width of the core portion on the upstream side of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the first Even when the widths of the two curved portions are all constant and equal in the length direction, the amount of light leaking can be reduced in the second curved portion, and the light propagation in the core is made more appropriate. be able to. And in the position sensor of this invention, the light reception intensity | strength in a light receiving element can be equalized, and a press position can be detected correctly.

On the other hand, the width of the outlet of the first curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the outlet of the first curved portion (B1: unit μm) The radius of curvature (R1: unit mm) of the first curved portion, the refractive index (K1) of the core on which the S-shaped portion is formed, and the refractive index (K2) of the cladding layer covering the side surface of the core ) Also satisfies the following formula (3), the optical waveguide of the present invention can further reduce the amount of light that propagates in the second curved portion. Therefore, in the optical circuit board of the present invention, when the optical member receives light from the end portion of the core of the optical waveguide, it is possible to further suppress a decrease in light reception intensity of the optical member. In addition, it is possible to improve the certainty of realizing proper operation of an electronic device or the like incorporating the optical circuit board. The radius of curvature (R1) of the first curved portion is the radius of curvature of the center line in the width direction of the first curved portion.

In addition, the width of the outlet of the first curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion is the inlet of the first curved portion. The width of the straight line portion and the width of the second curved portion are constant in the length direction, respectively, and the width of the outlet of the first curved portion, Even when the width of the straight line portion is equal to the width of the second curved portion, the amount of light leaking can be reduced in the second curved portion, and the light propagation in the core can be more appropriately performed. can do. Therefore, in the optical circuit board of the present invention, it is possible to suppress a decrease in the light receiving intensity of the light at the optical member. And proper operation | movement of the electronic device etc. which incorporated the optical circuit board can be implement | achieved reliably.

(A) is a plan view schematically showing a first embodiment of the position sensor of the present invention, and (b) is an enlarged cross section schematically showing a central portion of the XX cross section of (a). It is a figure and (c) is an enlarged plan view which shows typically the S-shaped part of the core currently formed in the part enclosed with the ellipse D1 of (a). It is an enlarged plan view which shows typically the said S-shaped part in 2nd Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 3rd Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 4th Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 5th Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 6th Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 7th Embodiment of the position sensor of this invention. It is an enlarged plan view which shows typically the said S-shaped part in 8th Embodiment of the position sensor of this invention. It is an expanded sectional view of the central part of the optical waveguide which shows typically the modification of the optical waveguide which constitutes the above-mentioned 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 plan view schematically showing a first embodiment of an optical circuit board of the present invention, and (b) is a sectional view schematically showing a YY section of (a). (C) is an enlarged plan view schematically showing an S-shaped part of a core formed in a part surrounded by an ellipse D2 in (a). It is an enlarged plan view which shows typically the said S-shaped part in 2nd Embodiment of the optical circuit board of this invention. It is a top view which shows typically 3rd Embodiment of the optical circuit board of this invention. (A), (b) is an expanded sectional view of the optical waveguide which shows typically the modification of the optical waveguide which constitutes the above-mentioned optical circuit board. It is a graph which shows the result of Experimental example 1 and 2. (A) is a top view which shows typically the conventional position sensor, (b) is an enlarged plan view which shows typically the said S-shaped part of (a). It is a longitudinal cross-sectional view which shows the conventional optical circuit board typically.

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

FIG. 1A is a plan view showing a first embodiment of the position sensor of the present invention, and FIG. 1B is an enlarged view of the central portion of the XX cross section of FIG. It is. The position sensor of this embodiment is arranged in a rectangular sheet-shaped optical waveguide W and two rectangular corner portions of the optical waveguide W adjacent to each other (two upper corner portions in FIG. 1A). Two light emitting elements 4 and two light receiving elements 5 arranged at the remaining two corner portions (the lower two corner portions in FIG. 1A) are provided.

In the optical waveguide W, a sheet-like core pattern member is formed on the surface of a rectangular sheet-like underclad layer 1, and the surface of the underclad layer 1 is covered with a rectangular sheet-like shape in a state of covering the core pattern member. The over clad layer 3 is formed. The core pattern member includes a lattice-shaped portion 2A formed by arranging a plurality of linear optical path cores 2 vertically and horizontally, one horizontal side and one vertical side of the outer peripheral portion of the lattice-shaped portion 2A [FIG. ) In the upper side and the right side, respectively, and face the first lateral side and the vertical side through the grid-like portion 2A, respectively, extending along the respective sides. It has a second outer peripheral core portion 2 </ b> C that is located on the other horizontal side and the other vertical side (the lower side and the left side in FIG. 1A) and extends along each other side.

The first outer core portion 2B is composed of one core 21, and the tip of each vertical core 2 (upper end in FIG. 1 (a)) and the tip of each horizontal core 2 (FIG. 1 (a)). ) Is optically connected to the right end]. Thereby, each of the vertical cores 2 and the horizontal cores 2 is branched from the first outer peripheral core portion 2B. 2 C of said 2nd outer periphery core parts are the core 22 extended from the rear end [lower end in FIG. 1 (a)] of each said vertical core 2, and the rear end [left end in FIG. 1 (a)] of each horizontal core 2. As shown in FIG. It is made up of. And the said light emitting element 4 is connected to the end surface of the said 1st outer periphery core part 2B, and the said light receiving element 5 is connected to the end surface of the said 2nd outer periphery core part 2C.

In FIG. 1A, the cores 2, 21, and 22 are indicated by chain lines, and the number of the cores 2 in the lattice-shaped portion 2 </ b> A and the cores 22 of the second outer peripheral core portion 2 </ b> C extending from the cores 2. The numbers are abbreviated. Moreover, the arrow of the core 2 of Fig.1 (a) has shown the direction where light travels.

As shown in the enlarged plan view of FIG. 1 (c), the position sensor of this embodiment is characterized by the vicinity of the light receiving element 5 of the core 22 that is a part of the second outer peripheral core 2C [FIG. a) the core width of the S-shaped part formed in the part surrounded by the ellipse D1]. That is, FIG. 1C shows an enlarged plan view of an S-shaped portion of one core 22 among the plurality of cores 22 of the second outer peripheral core portion 2C. In this embodiment, the S-shaped portion includes a first curved portion S1 on the upstream side of light propagation and a second curved portion S2 on the downstream side that is bent in the opposite direction to the first curved portion S1. , Formed in a continuously connected state. The width of the inlet of the S-shaped part (the inlet of the first curved part S1) is equal to the width B0 of the core part upstream of the S-shaped part. In the S-shaped part, the width of the first curved part S1 is gradually narrowed from the inlet of the first curved part S1 to the outlet, and the width of the outlet of the first curved part S1 is The width B2 of the entrance of the two curved portions S2 is equal. The width of the second curved portion S2 is constant in the length direction. Thereby, the width B2 of the entrance of the second curved portion S2 is narrower than the width B0 of the core portion on the upstream side of the S-shaped portion.

Thus, by setting the S-shaped part to a characteristic core width, leakage of the light L in the S-shaped part can be reduced (propagation loss of the light L can be reduced). . That is, in the S-shaped portion, the light L (indicated by a two-dot chain line) is biased to the outer portion of the curve of the first curved portion S1 on the upstream side, and the light L propagates to the second curved portion S2 on the downstream side. Then, the light L is propagated in the vicinity of the entrance of the second curved portion S2 while being biased toward the inside of the bend, and is concentrated on the side surface outside the bend of the second curved portion S2. . Here, since the core width of the second curved portion S2 is narrowed by setting the characteristic core width of the S-shaped portion as described above, the light L that has reached the side surface has an incident angle. θ becomes larger than the critical angle. Therefore, most of the light L is reflected by the side surface, and leakage of the light L can be reduced. Then, in the core 22 of the second outer peripheral core portion 2C, the light L reaches the light receiving element 5 in a state where leakage of the propagating light L is reduced.

In such a position sensor, as shown in FIG. 1 (a), the light emitted from the light emitting element 4 branches from the core 21 of the first outer peripheral core portion 2B to each core 2 of the lattice portion 2A. The light receiving element 5 receives light through each core 22 of the second outer peripheral core portion 2C. The surface portion of the over clad layer 3 corresponding to the lattice-like portion 2A of the core pattern member [rectangular portion indicated by a one-dot chain line in the center of FIG. 1A] is an input region 3A.

Inputting characters or the like to the position sensor is performed by writing characters or the like in the input area 3A directly or via a resin film or paper with an input body such as a pen. At this time, the input area 3A is pressed with a pen tip or the like, the core 2 of the pressed portion is deformed, and the light propagation amount of the core 2 is reduced. For this reason, in the core 2 of the pressing portion, the light receiving intensity of the light receiving element 5 is reduced, so that the pressing position (XY coordinate) can be detected.

Here, as described above, in the core 22 of the second outer peripheral core portion 2C, the light reaches the light receiving element 5 in a state in which leakage of the propagating light is reduced. The light receiving intensity of the light at the light receiving element 5 can be equalized in a state where it is not pressed. For this reason, when the input region 3A is pressed, a portion where the light receiving intensity of the light at the light receiving element 5 decreases can be clarified. As a result, the position sensor can accurately detect the pressed position in the input area 3A.

Further, in the second curved line portion S2, the amount of light that propagates can be further reduced, thereby further equalizing the light receiving intensity of the light at the light receiving element 5 and improving the accuracy of detecting the pressed position. In view of the above, the width of the inlet of the second curved portion S2 (B2: unit μm), the radius of curvature of the second curved portion S2 (R2: unit mm), and the core formed with the S-shaped portion It is preferable to set the relationship between the refractive index (K1) of 22 and the refractive index (K2) of the over cladding layer 3 covering the side surface of the core 22 so as to satisfy the following formula (1). More preferably, it is set to satisfy the following formula (2). The radius of curvature (R2) of the second curved portion S2 is the radius of curvature of the center line in the width direction of the second curved portion S2.

Incidentally, since the light receiving element 5 is generally small, the light receiving element 5 has a narrow light receiving area connected to the core 22, and the number of the cores 22 connected to the light receiving area is limited. In the above position sensor, as described above, in the S-shaped portion formed in the vicinity of the light receiving element 5, the core width of the second curved portion S2 on the downstream side is narrow. If it is formed up to the tip of the core 22 with the reduced width, the number of cores 22 connected to the light receiving region can be increased. As a result, it is possible to increase the number of cores 2 of the grid-like portion 2A corresponding to the input area 3A, and it is possible to improve the position accuracy of the pressed position detected in the input area 3A.

In the optical waveguide W, it is preferable that the elastic modulus of the core 2 of the lattice-like portion 2A 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 the light receiving intensity of the light at the light receiving element 5 decreases in the core 2, so that the pressed position can be detected. The value of the elastic modulus is a value of the tensile elastic modulus measured using a dynamic viscoelasticity measuring device RSAIII manufactured by TA Instruments.

Examples of the material for forming the under cladding layer 1, the cores 2, 21, 22 and the over cladding layer 3 include a photosensitive resin and a thermosetting resin. The optical waveguide W is manufactured by a manufacturing method corresponding to the forming material. can do. The refractive indexes of the cores 2, 21, and 22 are set to be larger than the refractive indexes of the under cladding layer 1 and the over cladding layer 3. The refractive index and the elastic modulus can be adjusted by, for example, selecting the type of each forming material and adjusting the composition ratio. The thickness of each layer is, 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 cores 2, 21, 22, and from the top surface of the over cladding layer 3 (from the top surfaces of the cores 2, 21, 22). Is set within a range of 1 to 200 μm. A rubber sheet may be used as the under cladding layer 1 and the cores 2, 21, 22 may be formed on the rubber sheet.

FIG. 2 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the second embodiment of the position sensor of the present invention. In this embodiment, in the first embodiment shown in FIGS. 1A to 1C, the S-shaped portion has the first curved portion S1 and the second curved portion S2, and the length is zero. It is formed in a connected state via a straight portion T that exceeds (zero) mm and is 30 mm or less. The width of the straight line portion T is constant in the length direction, and is equal to the width of the outlet of the first curved portion S1 (the width B2 of the inlet of the second curved portion S2). Other parts are the same as those of the first embodiment, and the same reference numerals are given to the same parts.

In this embodiment, although the straight part T is formed between the first curved part S1 and the second curved part S2, the length of the straight part T is as short as 30 mm or less, so the first curved part S1. The light L (shown by a two-dot chain line) propagated from the straight line T to the straight line part T is propagated to the second curved line part S2 with almost no reflection on the side surface of the straight line part T. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 3 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the third embodiment of the position sensor of the present invention. In this embodiment, in the first embodiment shown in FIGS. 1A to 1C, the width of the first curved portion S1 of the S-shaped portion is constant in the length direction, It is equal to the width B0 of the core portion upstream from the S-shaped portion. The second curved portion S2 is the same as the first embodiment, the width is constant in the length direction, and the width B2 of the inlet of the second curved portion S2 is upstream of the S-shaped portion. It is narrower than the width B0 of the core portion on the side. The inlet of the second curved portion S2 is disposed in a portion of the outlet of the first curved portion S1 corresponding to the outside of the bend of the first curved portion S1 in the width direction. That is, the S-shaped portion is formed in a stepped shape at the connecting portion between the first curved portion S1 and the second curved portion S2, and the width of the connecting portion is outside the bend of the first curved portion S1 (first It is narrowed at a stretch to the inside of the bend of the two curved portion S2. Other parts are the same as those of the first embodiment, and the same reference numerals are given to the same parts.

In this embodiment, although the width of the connecting portion between the first curved portion S1 and the second curved portion S2 is narrowed to the outside of the bend of the first curved portion S1, it is the same as in the first embodiment. Moreover, since the light L (indicated by a two-dot chain line) propagating through the first curved portion S1 is biased toward the outer portion of the curve, most of the light L is propagated to the second curved portion S2. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 4 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the fourth embodiment of the position sensor of the present invention. In this embodiment, in the third embodiment shown in FIG. 3, the S-shaped portion is such that the first curved portion S1 and the second curved portion S2 have a length exceeding 0 (zero) mm and 30 mm. It is formed in a connected state via the following straight line portion T. The entrance of the straight line portion T is disposed at a portion of the exit of the first curved portion S1 corresponding to the outside of the bend of the first curved portion S1 in the width direction. The width of the straight portion T is constant in the length direction and is equal to the width B2 of the entrance of the second curved portion S2. That is, the connection part of 1st curve part S1 and the linear part T is formed in step shape, and the width | variety of the connection part is narrowing to the outer side of the curve of 1st curve part S1 at a stretch. Other parts are the same as those in the third embodiment, and the same reference numerals are given to the same parts.

In this embodiment, the width of the connecting portion between the first curved portion S1 and the straight portion T is narrowed to the outside of the bend of the first curved portion S1, but as in the third embodiment, Since the light L (indicated by a two-dot chain line) propagating through the first curved line portion S1 is biased toward the outer portion of the curve, most of the light L is propagated to the straight line portion T. Moreover, the light L is propagated to the second curved line portion S2 with almost no reflection on the side surface of the straight line portion T, as in the second embodiment shown in FIG. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 5 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the fifth embodiment of the position sensor of the present invention. In this embodiment, in the fourth embodiment shown in FIG. 4, the width of the first curved line portion S1 and the width of the straight line portion T are equal. In addition, the entrance of the second curved portion S2 is disposed at a portion of the exit of the straight portion T corresponding to the outside of the bend of the first curved portion S1 in the width direction. That is, the connecting portion between the straight portion T and the second curved portion S2 is formed in a step shape, and the width of the connecting portion is narrowed to a portion corresponding to the outside of the bend of the first curved portion S1. Other parts are the same as those in the fourth embodiment, and the same reference numerals are given to the same parts.

In this embodiment, the light L (indicated by a two-dot chain line) that is biased and propagated to the outer portion of the bend of the first curved portion S1 is propagated to the portion corresponding to the outer portion even in the straight portion T as it is. Is done. Moreover, the light L propagating to the straight line portion T is propagated to the second curved line portion S2 with almost no reflection on the side surface of the straight line portion T, as in the fourth embodiment. Therefore, even if the width of the connecting portion between the straight portion T and the second curved portion S2 is narrowed to the outer portion of the straight portion T as described above, most of the light L propagating through the straight portion T is first. Propagated to the two curve portion S2. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 6 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the sixth embodiment of the position sensor of the present invention. In this embodiment, in the fifth embodiment shown in FIG. 5, the width of the inlet of the straight portion T is equal to the width of the first curved portion S1, and the width of the outlet of the straight portion T is the first width. The width of the two curved portions S2 is equal. That is, the straight part T is formed in a tapered shape whose width gradually decreases from the entrance to the exit. Other parts are the same as those in the fifth embodiment, and the same reference numerals are given to the same parts.

Also in this embodiment, the light L (shown by a two-dot chain line) that is biased and propagated to the outer portion of the curve of the first curved portion S1 is propagated to the portion corresponding to the outer portion of the straight portion T as it is. The Moreover, the light L propagated to the straight line portion T is propagated to the second curved line portion S2 with almost no reflection on the side surface of the straight line portion T, as in the fifth embodiment. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 7 is an enlarged plan view (corresponding to FIG. 1C) showing the S-shaped portion in the seventh embodiment of the position sensor of the present invention. In this embodiment, in the third embodiment shown in FIG. 3, the width of the first curved portion S1 is equal to the width of the second curved portion S2, and is narrowed. That is, the widths of the S-shaped portions are all constant and equal in the length direction, and are narrower than the width B0 of the core portion on the upstream side of the S-shaped portions. Other parts are the same as those in the third embodiment, and the same reference numerals are given to the same parts.

In this embodiment, the width of the S-shaped portion is constant and equal in the length direction, and is narrower than the width B0 of the core portion upstream of the S-shaped portion. However, the light L (indicated by a two-dot chain line) propagating toward the outer portion of the curve of the first curved portion S1 is propagated as it is to the second curved portion S2. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

FIG. 8 is an enlarged plan view (a diagram corresponding to FIG. 1C) showing the S-shaped portion in the eighth embodiment of the position sensor of the present invention. In this embodiment, in the seventh embodiment shown in FIG. 7, the S-shaped portion is such that the first curved portion S1 and the second curved portion S2 have a length exceeding 0 (zero) mm and 30 mm. It is formed in a connected state via the following straight line portion T. The width of the straight line portion T is constant in the length direction and is equal to the width of the first curved portion S1 (the width of the second curved portion S2). Other parts are the same as those in the seventh embodiment, and the same reference numerals are given to the same parts.

Also in this embodiment, the light L (shown by a two-dot chain line) that is biased and propagated to the outer portion of the curve of the first curved portion S1 is propagated to the portion corresponding to the outer portion of the straight portion T as it is. The In addition, the light L propagated to the straight line portion T is propagated to the second curved line portion S2 with almost no reflection on the side surface of the straight line portion T, as in the second embodiment shown in FIG. . And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, the light L propagated to the 2nd curve part S2 is the same as that of the said 1st Embodiment, The light receiving element 5 is reached in a state where leakage is reduced. In other words, the position sensor of this embodiment also has the same operations and effects as the first embodiment.

In each of the above embodiments, the core 22 having the S-shaped portion is defined as a part of the second outer peripheral core portion 2C. However, the S-shaped portion is formed on all the cores 22. May be.

Further, in each of the above-described embodiments, the cross-sectional structure of the optical waveguide W is shown in FIG. 1B, 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.

In each of the above-described 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 the enlarged plan view in FIG. Others are acceptable. For example, as shown in FIG. 10B, 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. 10 (c) and 10 (d), the two intersecting directions [FIG. 10 (c) is two opposing directions and FIG. 10 (d) is two adjacent directions] are discontinuous. As shown in FIG. 10 (e), the three intersecting directions may be discontinuous, or as shown in FIG. 10 (f), all the four intersecting directions may be discontinuous. It may be discontinuous. Furthermore, a lattice shape having two or more types of intersections among the intersections shown in FIGS. 10 (a) to 10 (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. 10B to 10F, if at least one intersecting direction is discontinuous, the light crossing loss can be reduced. That is, as shown in FIG. 11 (a), at an intersection where all four intersecting directions are continuous, if one of the intersecting directions [upward in FIG. 11 (a)] is focused, the light incident on the intersection Part of the light reaches the side surface 2a of the core 2 orthogonal to the core 2 through which the light has traveled, and the incident angle at the side 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. 11A). On the other hand, as shown in FIG. 11 (b), when one intersecting direction (upward in FIG. 11 (b)) 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. 11 (a) 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. 11B). 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.

In each of the above embodiments, the optical waveguide W is formed in a rectangular sheet shape. However, as long as the optical waveguide W has a lattice-shaped core 2, it may be formed in another polygonal sheet shape.

FIG. 12A is a plan view showing the first embodiment of the optical circuit board of the present invention, and FIG. 12B is a longitudinal sectional view taken along the central axis of the core of FIG. (YY sectional view). The optical circuit board 30 of this embodiment is also laminated on the electric circuit board 40 in the same manner as the conventional optical circuit board 70 (see FIG. 18). Then, as shown in the plan view of FIG. 12A, the optical circuit board 30 includes two light emitting elements 34 on one end side (upper end side in the figure) and the other end side (lower end side in the figure). In addition, two light receiving elements 35 are provided. The interval between the two light receiving elements 35 on the other end side is set wider than the interval between the two light emitting elements 34 on the one end side. Thereby, the width of the optical circuit board 70 is narrow at one end side and wide at the other end side, and the interval between the adjacent cores 32 that propagate light between the light emitting element 34 and the light receiving element 35 is The light receiving element 35 side is set wider than the light emitting element 34 side. Along with this, the core 32 is bent in an S shape at the central portion in the length direction (portion surrounded by the ellipse D2 in FIG. 12A). In FIG. 12A, the width of the core 32 is exaggerated.

In this embodiment, the S-shaped portion of the core 32 includes, as shown in an enlarged plan view in FIG. 12C, a first curved portion S1 on the upstream side of light propagation and the first curved portion S1. The second curved portion S2 on the downstream side bent in the opposite direction is formed in a continuously connected state. The width of the inlet of the S-shaped part (the inlet of the first curved part S1) is equal to the width B0 of the core part upstream of the S-shaped part. And the width | variety of 1st curve part S1 becomes narrow gradually as it goes to the exit from the entrance of the 1st curve part S1, and width B1 of the exit of the 1st curve part S1 is 2nd curve part S2. The entrance width B2 is equal. The width of the second curved portion S2 is constant in the length direction.

Other portions are the same as those of the conventional electric circuit board 80 and optical circuit board 70 shown in FIG. That is, in FIG. 12B, reference numeral 41 is an insulating layer, reference numeral 42 is an electrical wiring formed on the surface of the insulating layer 41 (not shown in FIG. 12A), and reference numerals 41a and 41b are the above insulating layers. Reference numeral W2 denotes an optical waveguide, reference numerals 32a and 32b denote light reflecting surfaces formed at both ends of the core 32, reference numeral 31 denotes a first cladding layer, and reference numeral 33 denotes a second cladding layer. The one end of the core 32 and the light emitting element 34 are optically connected, and the other end of the core 32 and the light receiving element 35 are optically connected. The light L (indicated by a two-dot chain line) emits light. The light propagates from the element 34 to the light receiving element 35 through the core 32.

In the S-shaped portion of the core 32, the leakage of the light L in the S-shaped portion is reduced by setting the characteristic core width (the propagation loss of the light L is reduced). )be able to. That is, in the S-shaped portion, as shown in FIG. 12C, the width B1 of the outlet of the first curved portion S1 on the upstream side is set to the width B0 of the core portion on the upstream side of the S-shaped portion. The light L (indicated by a two-dot chain line) that propagates is propagated to the second curved line portion S2 on the downstream side in a state of being biased toward the outer portion of the bending of the first curved line portion S1 on the upstream side. The Then, the light L propagates in the vicinity of the entrance of the second curved portion S2 while being biased toward the inside of the bend, and concentrates on the side surface outside the bend of the second curved portion S2. Here, the width B2 of the entrance of the second curved portion S2 is equal to and narrower than the width B1 of the exit of the first curved portion S1, and the width of the second curved portion S2 is constant in the length direction. Therefore, the incident angle θ of the light L that has reached the outer side surface of the curve of the second curved portion S2 is larger than the critical angle. Therefore, most of the light L is reflected by the side surface, and leakage of the light L can be reduced. Thus, in the core 32, the light L reaches the light receiving element 35 in a state where leakage of the propagating light L is reduced.

Furthermore, in the second curved line portion S2, the amount of light that propagates can be further reduced, and thereby, from the viewpoint of further suppressing the decrease in the light receiving intensity of the light at the light receiving element 5, the first curved portion. The width of the exit of S1 (B1: unit μm), the radius of curvature of the first curved portion S1 (R1: unit mm), the refractive index of the core on which the S-shaped part is formed (K1), It is preferable to set the relationship with the refractive index (K2) of the second cladding layer 33 covering the side surface of the core 32 so as to satisfy the following formula (3). The radius of curvature (R1) of the first curved portion S1 is the radius of curvature of the center line in the width direction of the first curved portion S1.

Further, the core width of the first curved portion S1 is preferably set within a range of 1 to 80 μm including the inlet and the outlet. The radius of curvature (R1) of the first curved part S1 is preferably set within a range of 0.5 to 5.0 mm, for example. Further, the refractive index difference (K1−K2) is preferably set within a range of 0.005 to 0.05, for example.

FIG. 13 is an enlarged plan view (corresponding to FIG. 12C) showing the S-shaped portion in the second embodiment of the optical circuit board of the present invention. In this embodiment, in the first embodiment shown in FIGS. 12 (a) to 12 (c), the S-shaped portion has the first curved portion S1 and the second curved portion S2, and the length is zero. It is formed in a connected state via a straight portion T that exceeds (zero) mm and is 30 mm or less. The width of the straight line portion T is constant in the length direction and is equal to the width B1 of the outlet of the first curved portion S1 (the width B2 of the inlet of the second curved portion S2). Other parts are the same as those of the first embodiment, and the same reference numerals are given to the same parts.

Also in this embodiment, in the S-shaped portion, the width B1 of the outlet of the first curved portion S1 on the upstream side is narrower than the width B0 of the core portion on the upstream side of the S-shaped portion. Accordingly, the propagating light L (indicated by a two-dot chain line) is propagated to the straight line portion T in a state of being biased toward the outer portion of the curve of the first curved line portion S1 on the upstream side. And since the length of the straight line portion T is as short as 30 mm or less, the light L propagated from the first curved line portion S1 to the straight line portion T is hardly reflected on the side surface of the straight line portion T, and remains biased. In the state, it is propagated to the second curved line portion S2. As in the first embodiment, the light L propagates in the vicinity of the entrance of the second curved portion S2 while being biased to the inside of the bend, and the side surface outside the bend of the second curved portion S2. Concentrate on to reach. And since the 2nd curve part S2 is the same as that of the said 1st Embodiment, most of the light L which reached | attained the said side surface reflects on the side surface, and can reduce the leakage of the light L. As described above, the light L propagated to the second curved portion S2 reaches the light receiving element 5 in a state where leakage is reduced in the same manner as in the first embodiment. That is, the optical circuit board according to this embodiment also has the same operations and effects as those of the first embodiment.

FIG. 14 is a plan view showing a third embodiment of the optical circuit board of the present invention. In this embodiment, a large number of electronic components 50 such as an optical element 54, an IC chip interface, a resistor, a capacitor, and a coil are arranged on the surface of the insulating layer 61, and a plurality of the optical elements 54 are One end of the core 52 of the optical waveguide W3 is optically connected, and the other end of the core 52 is optically connected to the optical fiber connector 55. Since the core 52 is arranged and formed so as to avoid the electronic components 50 arranged in a distributed manner, a part thereof (a part surrounded by an ellipse D3 in FIG. 14) is formed in an S shape. And the S-shaped part is set to the characteristic core width similarly to 1st Embodiment shown in FIG.12 (c), or 2nd Embodiment shown in FIG. Other parts are the same as those in the first or second embodiment. The optical circuit board according to this embodiment also has the same operations and effects as those of the first or second embodiment.

The cross-sectional structure of the optical waveguides W2 and W3 in the respective embodiments of the optical circuit board (the cross-sectional structure corresponding to FIG. 1B and FIG. 9) may be the cross-sectional structure shown in FIG. The cross-sectional structure shown in FIG. That is, in the cross-sectional structure shown in FIG. 15A, the lower surface of the first cladding layer 31 is formed with the core 32 projecting from the lower surface of the first cladding layer 31 and covering the side surface and the lower surface of the core 32. In addition, the second cladding layer 33 is formed. On the other hand, the cross-sectional structure shown in FIG. 15B is an upside down version of the cross-sectional structure shown in FIG. That is, the core 32 is embedded in the lower surface portion of the first cladding layer 31, and the lower surface of the first cladding layer 31 and the lower surface of the core 32 are formed flush with each other. The second clad layer 33 is formed in a state where the lower surface of 32 is covered.

Further, in each of the embodiments of the position sensor and the optical circuit board, the width of the second curved portion S2 on the downstream side of the S-shaped portion is constant in the length direction. Since the light propagation loss at has a tendency to become lower as the width of the second curved portion S2 is narrower, it may be gradually reduced from the entrance to the exit of the second curved portion S2.

In each of the above embodiments, the optical waveguides W, W2, and W3 having the cores 22 and 32 having the S-shaped portions are used for the position sensor and the optical circuit board. It is good also as an optical waveguide of other uses.

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

[Formation material of under clad layer and over clad layer]
Component a: 60 parts by weight of an epoxy resin (Mitsubishi Chemical Corporation, YX7400).
Component b: 40 parts by weight of epoxy resin (manufactured by Daicel, EHPE3150).
Component c: 1 part by weight of a photoacid generator (manufactured by San Apro, CPI-101A).
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: 100 parts by weight of epoxy resin (manufactured by Daicel, EHPE3150).
Component e: 1 part by weight of a photoacid generator (manufactured by Adeka, SP-170).
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.

[Example 1]
Using each of the above forming materials, an optical waveguide in which a part of the core was formed in an S shape was produced. In the S-shaped portion, the width of the first curved portion S1 gradually becomes narrower as it goes from the inlet of the first curved portion S1 to the outlet, and the width B2 of the inlet of the second curved portion S2 becomes the S-shape. It is assumed that it is narrower than the width B0 of the core portion on the upstream side of the shape portion (see FIG. 1C). And the width | variety B2 of the entrance of 2nd curve part S2 was set to the various value shown in following Table 1. FIG. Table 1 shows other dimensions, refractive index, and the like. In addition, the width B0 of the core portion on the upstream side from the S-shaped portion was set to 200 μm. The thickness of the under cladding layer was 25 μm, the core thickness was 30 μm, and the thickness of the over cladding layer from the top surface of the core was 70 μm.

[Comparative Example 1]
In Example 1, the width of the S-shaped part was as wide as 200 μm and was set as Comparative Example 1. The other parts were the same as in Example 1 above.

(Measurement of light propagation loss)
A light emitting element (XH85-S0603-2s, manufactured by Optowell) was connected to one end face of the core of the optical waveguide, and a light receiving element (s10226, manufactured by Hamamatsu Photonics) was connected to the other end face of the core. Then, the light propagation loss (α) is calculated from the light emission intensity (E) of the light emitting element and the light reception intensity (F) of the light receiving element according to the following formula (4), and is shown in Table 1 below. .

From the results of Table 1 above, it can be seen that Example 1 has a smaller light propagation loss than Comparative Example 1. For this reason, the width B2 of the entrance of the second curved portion of the S-shaped portion is narrower than the width B0 of the core portion on the upstream side of the S-shaped portion, thereby reducing the light propagation loss. It can be seen that this is effective. In addition, Example 1 satisfy | fills said Formula (1).

[Examples 2 to 4 and Comparative Examples 2 and 3]
In Example 1 and Comparative Example 1, by changing the material for forming the overcladding layer, the refractive index of the overcladding layer was changed, and these were designated as Examples 2 to 4 and Comparative Examples 2 and 3. Then, the light propagation loss was calculated in the same manner as in Example 1. The results are shown in Tables 2 and 3 below.

From the results shown in Tables 2 and 3, it can be seen that Examples 2 to 4 also have smaller light propagation loss than Comparative Examples 2 and 3. Also from this fact, the width B2 of the entrance of the second curved portion of the S-shaped portion is narrower than the width B0 of the core portion upstream of the S-shaped portion. It turns out that it is effective in making it small. Examples 2 to 4 also satisfy the above formula (1).

Also, the results showing the same tendency as in Examples 1 to 4 were obtained for the optical waveguide having the core with the S-shaped portion formed as shown in FIGS.

[Position sensor]
A position sensor shown in FIG. 1A having a second outer peripheral core portion formed with the respective S-shaped portions was produced. The light emitting element and the light receiving element were the same as described above.

[Measurement of received light intensity]
In the position sensor, when the intensity of light received by the light receiving element is measured without pressing the input area, the second portion in which the S-shaped portion shown in FIG. 1 (c) and FIGS. 2 to 8 is formed. In the position sensor having the outer peripheral core portion, the entire input region was uniform. On the other hand, in the position sensor having the second outer peripheral core portion in which the S-shaped portion of Comparative Examples 1 to 3 is formed, the portion corresponding to the core in which the S-shaped portion is formed is weak and uneven. It was.

[Experimental Example 1]
Using the same forming material as in Example 1, an optical waveguide in which a part of the core was formed in an S shape was produced. The S-shaped part has an inlet width of the first curved portion of 200 μm, an outlet width of 40 μm, a radius of curvature of 10 mm, an inlet width of the second curved portion of 40 μm, an outlet width of 15 μm, and a radius of curvature. Was 10 mm. Note that the width of the inlet of the first curved portion is the same as the width of the core portion upstream of the S-shaped portion. Then, a straight line portion is provided between the first curve portion and the second curve portion, the length of the straight line portion is increased from 0 (zero) mm by 1.2 mm, and the length of each straight line portion is In the same manner as in Example 1, the light propagation loss was calculated. The results are shown in the graph of FIG.

[Experiment 2]
In Experimental Example 1, the width of the first curved portion was set to be as wide as 200 μm, the width of the inlet of the second curved portion was 200 μm, the width of the outlet was 15 μm, and the radius of curvature was 10 mm. Then, the light propagation loss was calculated in the same manner as in Experimental Example 1. The results are shown together with the graph of FIG.

From the graph of FIG. 16, it can be seen that in Experiment Example 1, the light propagation loss is substantially constant regardless of the length of the straight line portion. On the other hand, in Experimental Example 2, when the length of the straight portion is 30 mm or less, the light propagation loss tends to increase as the length of the straight portion is shorter. When the length of the straight portion exceeds 30 mm, It can be seen that the light propagation loss is substantially the same as Experimental Example 1 and is substantially constant. From these facts, when the length of the straight portion is 30 mm or less, in order to reduce the light propagation loss, the width of the inlet of the second curved portion is set to the width of the core portion on the upstream side of the S-shaped portion. It turns out that it is effective to make narrower than.

Further, as an optical waveguide for an optical circuit board to be laminated on an electric circuit board, an optical waveguide in which a part of a core is formed in an S-shape is manufactured using the following new forming materials [FIG. ), See (b)].

[Formation materials of the first cladding layer and the second cladding layer]
Component g: 60 parts by weight of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1001).
Component h: 30 parts by weight of an epoxy resin (manufactured by Daicel, EHPE3150).
Ingredient i: 10 parts by weight of an epoxy resin (manufactured by DIC, EXA-4816).
Component j: 0.5 part by weight of a photoacid generator (manufactured by Sun Apro, CPI-101A).
Component k: 0.5 part by weight of an antioxidant (Songnox 1010, manufactured by Kyodo Yakuhin Co., Ltd.).
Component l: 0.5 part by weight of an antioxidant (manufactured by Sanko Co., Ltd., HCA).
Component m: 50 parts by weight of ethyl lactate (manufactured by Wako Pure Chemical Industries, Ltd., solvent).
By mixing these components g to m, materials for forming the first cladding layer and the second cladding layer were prepared.

[Core forming material]
Component n: 50 parts by weight of epoxy resin (manufactured by Nippon Steel Chemical Co., Ltd., YDCN-700-3).
Component o: 30 parts by weight of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1001).
Component p: 20 parts by weight of epoxy resin (Ogsol PG-100, manufactured by Osaka Gas Chemical Company).
Component q: 0.5 part by weight of a photoacid generator (manufactured by Sun Apro, CPI-101A).
Ingredient r: 0.5 weight part of antioxidant (Kyodo Pharmaceutical Co., Ltd., Songnox 1010).
Ingredient s: 0.125 weight part of antioxidant (manufactured by Sanko Co., Ltd., HCA).
Component t: 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 n to t.

[Examples 5 to 9]
In Examples 5 to 9, the width of the first curved portion S1 of the S-shaped portion is gradually narrowed from the inlet of the first curved portion S1 to the outlet, and the width of the outlet of the first curved portion S1. B1 is assumed to be narrower than the width B0 of the core portion on the upstream side of the S-shaped portion [see FIGS. 12 (c) and 13]. And the width | variety B1 of the exit of 1st curve part S1, radius of curvature R1, etc. were set to the various values shown in the following Table 4. In addition, the width of the inlet of the first curved line portion S1 is set to the same value as the width B0 of the core portion upstream of the S-shaped portion. Further, the width of the straight line portion T (Examples 6 to 9) and the width of the second curved line portion S2 are constant in the length direction, and the same value as the width B1 of the outlet of the first curved line portion S1. And the curvature radius of 2nd curve part S2 was 0.5 mm in any Example. The thickness of the first cladding layer was 25 μm, the core thickness (projection height from the lower surface of the first cladding layer) was 30 μm, and the thickness of the second cladding layer from the lower surface of the core was 70 μm.

[Comparative Examples 4 to 6]
As shown in Table 4 below, in Comparative Example 4, the width of the first curved portion is gradually increased from the entrance to the outlet of the first curved portion, and in Comparative Examples 5 and 6, the first curved portion is widened. The width of the curved portion was constant in the length direction. And the curvature radius R1 etc. of 1st curve part S1 were set to the various values shown in following Table 4. FIG. The other parts were the same as in Examples 5 to 9.

(Measurement of light propagation loss)
GI type 50 μm diameter multimode optical fiber (manufactured by Miki Co., FFP-GI20-0500) connected with a VCSEL light source (Miki Co., OP250-LS-850-MM-50-SC, emission wavelength 850 nm): First light Fiber) and a multimode optical fiber (second optical fiber) having the same GI type diameter of 50 μm as described above, to which a light receiver (manufactured by Advantest, optical multimeter, Q8221) was connected. And the front-end | tip of the said 1st optical fiber and the front-end | tip of the said 2nd optical fiber were faced | matched, the light from the said VCSEL light source was received with the said light receiver, and the light reception intensity | strength (H) was measured.

Next, the tip of the first optical fiber is optically connected to a light reflecting surface (light incident portion) at one end of one core in the optical waveguides of Examples 5 to 9 and Comparative Examples 4 to 6. The tip of the second optical fiber was optically connected to the light reflecting surface (light emitting portion) at the other end of the core.
In this state, the light was received by the light receiver, and the received light intensity (I) was measured.

The light propagation loss (β) was calculated from the measured received light intensity (H, I) according to the following equation (5), and is shown in Table 4 below.

From the results in Table 4 above, it can be seen that Examples 5 to 9 have a smaller light propagation loss than Comparative Examples 4 to 6. For this reason, the width B1 of the exit of the first curved portion of the S-shaped portion is narrower than the width B0 of the core portion on the upstream side of the S-shaped portion, thereby reducing the light propagation loss. It can be seen that this is effective. In particular, it can be seen that in Examples 7 to 9 that satisfy the above-described expression (3), the light propagation loss is smaller.

Also, the optical waveguides in which the core part of the first to fourth embodiments is formed in an S-shape can be used as an optical waveguide for an optical circuit board as in the fifth to ninth embodiments. Results showing the same tendency as in Examples 5 to 9 were 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 optical waveguide of the present invention can be used for making the light propagation in the core more appropriate, and can be used as an optical communication application, for reducing the optical propagation loss in the optical communication application and saving the space for the core routing. It is valid. The position sensor of the present invention can be used when the received light intensity of the light receiving element is equalized in a state where the input area is not pressed. Further, the optical circuit board of the present invention can be used for suppressing a decrease in the light receiving intensity of the light in the optical element.

W2 Optical waveguide 32 Core S1 First curve portion S2 Second curve portion B0 Width of upstream core portion B1 Width of exit of first curve portion B2 Width of entrance of second curve portion

Claims (12)

An optical waveguide comprising a linear core for an optical path and a clad layer that sandwiches the core from above and below, the core partially including a first curved portion upstream of light propagation, and a first The second curved portion on the downstream side that is bent in the opposite direction to the curved portion is formed in an S-shape connected via a straight portion having a length of 0 (zero) mm to 30 mm, and the first curve One of the width of the outlet of the portion and the width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion. The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, the width of the inlet of the second curved portion (B2: unit μm), The radius of curvature (R2: unit mm) of the second curved portion, the refractive index (K1) of the core on which the S-shaped portion is formed, and the refractive index (K2) of the cladding layer covering the side surface of the core The optical waveguide according to claim 1, wherein the relationship satisfies the following expression (1).

The entrance width (B2: unit μm) of the second curved portion, the radius of curvature (R2: unit mm) of the second curved portion, and the refractive index (K1) of the core on which the S-shaped portion is formed The optical waveguide according to claim 2, wherein the relationship between the refractive index (K2) of the cladding layer covering the side surface of the core satisfies the following formula (2).

The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion is the outlet from the inlet of the first curved portion. The width of the straight line portion and the width of the second curved portion are constant in the length direction, and the width of the outlet of the first curved portion and the straight line are gradually reduced. The optical waveguide according to any one of claims 1 to 3, wherein a width of the portion is equal to a width of the second curved portion. The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the second curve The width of each of the portions is constant in the length direction, the width of the first curved portion is wider than the width of the second curved portion, and the width of the straight portion and the second portion The width of the curved portion is equal, and the inlet of the straight portion is arranged at a portion of the outlet of the first curved portion corresponding to the outside of the bend of the first curved portion in the width direction. The optical waveguide according to any one of claims 1 to 3. The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the second curve The width of each of the portions is constant in the length direction, the width of the first curved portion is wider than the width of the second curved portion, the width of the first curved portion, The width of the straight line portion is equal, and the inlet of the second curved portion is disposed in the width direction of the outlet of the straight portion corresponding to the outside of the bend of the first curved portion. The optical waveguide according to any one of claims 1 to 3. The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion and the width of the second curved portion are respectively The width of the first curved portion is wider than the width of the second curved portion, and the width of the inlet of the straight portion is the width of the first curved portion. The optical waveguide according to any one of claims 1 to 3, wherein an exit width of the straight line portion is equal to a width of the second curved portion. The width of the inlet of the second curved portion is narrower than the width of the core portion upstream of the S-shaped portion, the width of the first curved portion, the width of the straight portion, and the second curve The optical waveguide according to any one of claims 1 to 3, wherein all the widths of the portions are constant and equal in the length direction. The width of the outlet of the first curved portion is narrower than the width of the core portion upstream of the S-shaped portion, the width of the outlet of the first curved portion (B1: unit μm), and The radius of curvature (R1: unit mm) of the first curved portion, the refractive index (K1) of the core on which the S-shaped portion is formed, and the refractive index (K2) of the cladding layer covering the side surface of the core The optical waveguide according to claim 1, wherein the relationship satisfies the following expression (3).

The width of the outlet of the first curved portion is narrower than the width of the core portion upstream of the S-shaped portion, and the width of the first curved portion is from the inlet of the first curved portion to the outlet. The width of the straight line portion and the width of the second curved portion are constant in the length direction, and the width of the outlet of the first curved portion and the straight line are gradually reduced. The optical waveguide according to claim 1, wherein a width of the portion is equal to a width of the second curved portion. A lattice-shaped portion composed of a plurality of linear cores and one horizontal side and one vertical side of the outer peripheral portion of the lattice-shaped portion, respectively. The first outer peripheral core portion to be optically connected, and the other horizontal side and the other vertical side facing the one horizontal side and the one vertical side through the lattice portion, respectively, extend along each other side, A sheet-like core pattern member having a second outer peripheral core portion extending from the rear end of each vertical core and each horizontal core of the lattice-shaped portion, and a sheet sandwiching the core pattern member from above and below A sheet-like optical waveguide having a clad layer, a light-emitting element connected to the end face of the first outer core part of the optical waveguide, and a light-receiving element connected to the end face of the second outer core part A position sensor provided with a small amount of the second outer core portion. The portion of the optical waveguide corresponding to a part of the optical waveguide is the optical waveguide according to any one of claims 1 to 8, and light emitted from the light emitting element is emitted from the first outer core portion into the lattice shape. The surface portion of the position sensor corresponding to the lattice-shaped portion of the core pattern member is received by the light receiving element through the portion and the second outer peripheral core portion, and the pressing position in the input region is determined by the pressing. A position sensor characterized by being identified by a changed light propagation amount of a core. An optical circuit board comprising: the optical waveguide according to any one of claims 1, 9, and 10; and an optical member optically connected to an end of a core of the optical waveguide.

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