Manufacturing method of optical sensor module and optical sensor module obtained thereby

A method of manufacturing an optical sensor module which eliminates the need for the operation of alignment between a core in an optical waveguide section and an optical element in a substrate section, and an optical sensor module obtained thereby. An optical waveguide section W1 including groove portions (fitting portions) 4a for the positioning of a substrate section, and a substrate section E1 including fitting plate portions (to-be-fitted portions) 5a for fitting engagement with the groove portions 4a are individually produced. The fitting plate portions 5a in the substrate section E1 are brought into fitting engagement with the groove portions 4a in the optical waveguide section W1 whereby the substrate section E1 and the optical waveguide section W1 are integrated together.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing an optical sensor module including an optical waveguide section and a substrate section with an optical element mounted therein, and to an optical sensor module obtained thereby.

2. Description of the Related Art

As shown inFIGS. 13A and 13B, an optical sensor module is manufactured by: individually producing an optical waveguide section W0in which an under cladding layer71, a core72and an over cladding layer73are disposed in the order named, a substrate section E0in which an optical element82is mounted on a substrate81; and then connecting the above-mentioned substrate section E0to an end portion of the above-mentioned optical waveguide section W0, with the core72of the above-mentioned optical waveguide section W0and the optical element82of the substrate section E0kept in alignment with each other. InFIGS. 13A and 13B, the reference numeral74designates an adhesive layer,75designates a base,83designates an insulation layer,84designates an optical element mounting pad, and85designates a transparent resin layer.

The above-mentioned alignment between the core72of the above-mentioned optical waveguide section W0and the optical element82of the substrate section E0is generally performed by using a self-aligning machine (see, for example, Japanese Published Patent Application No. 5-196831). In this self-aligning machine, the alignment is performed with the optical waveguide section W0fixed on a fixed stage (not shown) and the substrate section E0fixed on a movable stage (not shown). Specifically, when the above-mentioned optical element82is a light-emitting element, the alignment is as follows. As shown inFIG. 13A, while the position of the light-emitting element is changed relative to a first end surface (light entrance)72aof the core72, with light H1emitted from the light-emitting element, the amount of light emitted outwardly from a second end surface (light exit)72bof the core72through a lens portion73bprovided in a second end portion of the over cladding layer73(the photovoltaic voltage developed across a light-receiving element91provided in the self-aligning machine) is monitored. Then, the position in which the amount of light is maximum is determined as an alignment position (a position in which the core72and the optical element82are appropriate relative to each other). On the other hand, when the above-mentioned optical element82is a light-receiving element, the alignment is as follows. As shown inFIG. 13B, the second end surface72bof the core72receives a constant amount of light (light emitted from a light-emitting element92provided in the self-aligning machine and transmitted through the lens portion73bprovided in the first end portion of the over cladding layer73) H2. While the position of the light-receiving element is changed relative to the first end surface72aof the core72, with the light H2emitted outwardly from the first end surface72aof the core72through a second end portion73aof the over cladding layer73, the amount of light received by the light-receiving element (the photovoltaic voltage) is monitored. Then, the position in which the amount of light is maximum is determined as the alignment position.

However, while the alignment using the above-mentioned self-aligning machine can be high-precision alignment, it requires labor and time and therefore unsuited for mass production.

DISCLOSURE OF THE INVENTION

In view of the foregoing, it is an object of the present invention to provide a method of manufacturing an optical sensor module which eliminates the need for the operation of alignment between a core in an optical waveguide section and an optical element in a substrate section, and an optical sensor module obtained thereby.

The present inventor has made studies of a method capable of achieving alignment without equipment and labor as mentioned above. As a result, the present inventor has hit upon the idea of a simple method in which a fitting portion is formed in a predetermined position of an over cladding layer in an optical waveguide section during the formation of the over cladding layer by die-molding whereas a to-be-fitted portion is formed in a predetermined position of a substrate section, and in which the above-mentioned optical waveguide section and the above-mentioned substrate section are coupled together to form an optical sensor module by fitting engagement between the above-mentioned fitting portion and the to-be-fitted portion. Thus, the present inventor has completed the present invention.

To accomplish the above-mentioned object, a first aspect of the present invention is intended for a method of manufacturing an optical sensor module including an optical waveguide section, and a substrate section with an optical element mounted therein, wherein said optical waveguide section is produced by forming a linear core for an optical path on a surface of an under cladding layer, and then forming fitting portions for the positioning of the substrate section in a portion of an over cladding layer lying in an appropriate position relative to an end portion of said core at the same time as forming the over cladding layer for covering said core by a die-molding process, wherein said substrate section is produced by placing an optical element mounting pad on a substrate, forming to-be-fitted port ions for fitting engagement with the fitting portions for the positioning of said substrate section in an appropriate position of the substrate relative to the optical element mounting pad, and mounting the optical element on said optical element mounting pad, and wherein said optical waveguide section and said substrate section are coupled together to form the optical sensor module by bringing said to-be-fitted portions in said substrate section into fitting engagement with said fitting portions in said optical waveguide section to integrate said optical waveguide section and said substrate section together.

A second aspect of the present invention is intended for an optical sensor module comprising: an optical waveguide section; and a substrate section with an optical element mounted therein, said optical waveguide section and said substrate section being coupled to each other, said optical waveguide section including an under cladding layer, a linear core for an optical path and formed on a surface of the under cladding layer, an over cladding layer for covering the core, and fitting portions for the positioning of the substrate section and formed in a predetermined portion of the over cladding layer, said substrate section including a substrate having to-be-fitted portions for fitting engagement with the fitting portions for the positioning of the substrate section, an optical element mounting pad placed in a predetermined portion on the substrate, and the optical element mounted on the optical element mounting pad, the coupling between said optical waveguide section and said substrate section being provided, with said to-be-fitted port ions in said substrate section held in fitting engagement with said fitting portions in said optical waveguide section.

In the step of producing the optical waveguide section in the method of manufacturing the optical sensor module according to the present invention, the fitting portions for the positioning of the substrate section are formed in a portion of the over cladding layer lying in an appropriate position relative to an end portion of the core at the same time as the over cladding layer during a die-molding process. In the produced optical waveguide section, the end portion of the core and the fitting portions for the positioning of the substrate section are placed in an appropriate positional relationship by such a die-molding process. In the step of producing the substrate section, on the other hand, the to-be-fitted portions for fitting engagement with the fitting portions for the positioning of the above-mentioned substrate section are formed in an appropriate position relative to the optical element mounting pad, and the optical element is mounted on the above-mentioned optical element mounting pad. In the substrate section produced in this manner, the optical element and the to-be-fitted portions are placed in an appropriate positional relationship. In the step of coupling the above-mentioned optical waveguide section and the above-mentioned substrate section together to form the optical sensor module, the above-mentioned to-be-fitted portions in the above-mentioned substrate section are brought into fitting engagement with the above-mentioned fitting portions in the above-mentioned optical waveguide section, whereby the above-mentioned optical waveguide section and the above-mentioned substrate section are integrated together. That is, in this step, the fitting portions placed in the appropriate positional relationship with the end portion of the core and the to-be-fitted portions placed in the appropriate positional relationship with the optical element are brought into fitting engagement with each other. Thus, the end portion of the core and the optical element are placed in an appropriate positional relationship in the manufactured optical sensor module. The method of manufacturing the optical sensor module according to the present invention enables the core of the optical waveguide section and the optical element of the substrate section to be automatically kept in alignment with each other without the operation of alignment therebetween. The method eliminates the need for the operation of alignment that requires time, to thereby achieve the mass production of such optical sensor modules.

In particular, when the above-mentioned fitting portions in the above-mentioned optical waveguide section are in the form of groove portions and the above-mentioned to-be-fitted portions in the above-mentioned substrate section are in the form of plate portions for fitting engagement with the above-mentioned groove portions, the method provides excellent productivity because the fitting engagement between the groove portions and the plate portions is easy.

Also, when the above-mentioned fitting portions in the above-mentioned optical waveguide section are in the form of protruding portions and the above-mentioned to-be-fitted portions in the above-mentioned substrate section are in the form of through hole portions for fitting engagement with the above-mentioned protruding portions, the method provides excellent precision of alignment between the core and the optical element because the central axis of each of the protruding portions is fixed even if the protruding portions thermally or otherwise contract or expand.

Since the optical sensor module according to the present invention is obtained by the above-mentioned manufacturing method, the end portion of the core of the optical waveguide section and the optical element of the substrate section are positioned by the fitting engagement between the fitting portions in the optical waveguide section and the to-be-fitted portions in the substrate section. Thus, if impacts, vibrations and the like are applied to the optical sensor module according to the present invention, the end portion of the above-mentioned core and the optical element do not move out of their positional relationship but are kept in appropriate alignment with each other.

In particular, when the above-mentioned fitting portions in the above-mentioned optical waveguide section are in the form of groove portions and the above-mentioned to-be-fitted portions in the above-mentioned substrate section are in the form of plate portions for fitting engagement with the above-mentioned groove portions, the simple fitting engagement structure provides tight fitting engagement.

Also, when the above-mentioned fitting portions in the above-mentioned optical waveguide section are in the form of protruding portions and the above-mentioned to-be-fitted portions in the above-mentioned substrate section are in the form of through hole portions for fitting engagement with the above-mentioned protruding portions, the optical sensor module maintains a high degree of precision of alignment between the core and the optical element because the central axis of each of the protruding portions is fixed even if the protruding portions thermally or otherwise contract or expand.

DETAILED DESCRIPTION OF THE INVENTION

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

FIG. 1Ais a plan view schematically showing an optical sensor module according to a first embodiment of the present invention, andFIG. 1Bis a sectional view taken along the line A-A ofFIG. 1A.FIG. 2is a perspective view showing a first end portion (the right-hand end portion as seen inFIGS. 1A and 1B) of the optical sensor module as seen diagonally from the upper right. This optical sensor module is constructed by: individually producing an optical waveguide section W1including groove portions (fitting portions)4afor the positioning of a substrate section, and a substrate section E1including fitting plate portions (to-be-fitted portions)5afor fitting engagement with the groove portions4a; and then bringing the above-mentioned fitting plate portions5ain the substrate section E1into fitting engagement with the above-mentioned groove portions4ain the above-mentioned optical waveguide section W1to integrate the substrate section E1and the optical waveguide section W1together. In the optical waveguide section W1, the above-mentioned groove portions4aare formed in an appropriate position relative to first end surfaces2aof respective cores2. An optical element is mounted in the substrate section E1, and the above-mentioned fitting plate portions5ahaving an appropriate shape are formed in an appropriate position relative to the optical element8. Thus, the first end surfaces2aof the respective cores2and the optical element8are appropriately positioned and in alignment with each other by the fitting engagement between the above-mentioned groove portions4aand the fitting plate portions5a. The above-mentioned optical waveguide section W1is bonded onto a base10that is an acrylic board or the like with an adhesive layer11therebetween. InFIGS. 1A,1B and2, clearance4bis shown as created between the groove portions4aof the optical waveguide section W1and the fitting plate portions5aof the substrate section E1for the sake of easier understanding of the figures. In reality, however, there is little clearance4btherebetween. InFIGS. 1A,1B and2, the reference numeral1designates an under cladding layer,3designates an over cladding layer,3bdesignates a lens portion,4designates extensions,5designates a shaping substrate,6designates an insulation layer,7designates an optical element mounting pad,9designates a transparent resin layer, the reference character10adesignates a through hole, and11designates the adhesive layer.

More specifically, the above-mentioned optical waveguide section W1includes the under cladding layer1, the cores2for an optical path formed linearly in a predetermined pattern on a surface of this under cladding layer1, and the over cladding layer3formed on the surface of the above-mentioned under cladding layer1so as to cover the cores2. A first end portion (on the right-hand side as seen inFIG. 1A) of the optical waveguide section W1includes upper and lower portions as seen inFIG. 1Aextended axially. That is, these extensions4are those of the under cladding layer1and the over cladding layer3where the cores2are absent. As shown inFIG. 2, the pair of groove portions4afor the positioning of the substrate section E1are formed in the extensions4, respectively, with the openings of the respective groove portions4ain face-to-face relation with each other. The groove portions4aare in the form of a kind of notch extending across the thickness of the under cladding layer1and the over cladding layer3. In this embodiment, the second end portion [the left-hand end portion as seen inFIGS. 1(a) and (b)] of the over cladding layer3is formed as the substantially quadrantal lens portion3bhaving an outwardly bulging surface.

On the other hand, the above-mentioned substrate section E1includes the shaping substrate5, the insulation layer6, the optical element mounting pad7, the optical element8, and the transparent resin layer9, as shown in perspective inFIG. 3. The above-mentioned shaping substrate5is formed with the fitting plate portions5aprotruding both leftwardly and rightwardly in cross direction as seen in the Figure for fitting engagement with the above-mentioned groove portions4a. The above-mentioned insulation layer6is formed on the surface of the above-mentioned shaping substrate5except where the fitting plate portions5aare formed. The above-mentioned optical element mounting pad7is formed on a central portion of the surface of the above-mentioned insulation layer6. The above-mentioned optical element8is mounted on the optical element mounting pad7. The above-mentioned transparent resin layer9is formed so as to seal the above-mentioned optical element8. The rectangular fitting plate portions5aincluded in the above-mentioned shaping substrate5and protruding leftwardly and rightwardly in cross direction as seen in the Figure are formed by etching, and are appropriately positioned and shaped relative to the above-mentioned optical element mounting pad7. The above-mentioned optical element8includes a light-emitting portion or a light-receiving portion formed on the surface of the optical element8. An electric circuit (not shown) for connection to the optical element mounting pad7is formed on the surface of the above-mentioned insulation layer6.

As shown inFIGS. 1A,1B and2, the above-mentioned optical sensor module is configured such that the optical waveguide section W1and the substrate section E1are integrated together by bringing the fitting plate portions5ain the above-mentioned substrate section E1into fitting engagement with the groove portions4ain the above-mentioned optical waveguide section W1which are provided for the positioning of the substrate section. The surface (the light-emitting portion or the light-receiving portion) of the above-mentioned optical element8is opposed to the first end surfaces2aof the respective cores2so as to be able to send or receive light. With this fitting engagement held, the above-mentioned optical element8is appropriately positioned in a vertical direction (along the X-axis) as seen inFIG. 1Arelative to the above-mentioned base10by the fitting engagement of the above-mentioned fitting plate portions5awith the above-mentioned groove portions4a. With the above-mentioned fitting engagement held, the lower edges of the above-mentioned fitting plate portions5aprotruding leftwardly and rightwardly in cross direction as seen in the Figure are in abutment with the surface of the base10, as shown inFIG. 2. This allows the appropriate positioning of the above-mentioned optical element8in a direction perpendicular to the surface of the base10(along the Y-axis). That is, the first end surfaces2aof the cores2and the optical element8are placed in an appropriate positional relationship and automatically kept in alignment with each other by the above-mentioned fitting engagement, as shown inFIG. 2.

In this embodiment, the rectangular through hole10ais formed in a portion of the base10corresponding to the above-mentioned substrate section E1, as shown inFIGS. 1A and 2, so that a portion of the substrate section E1protrudes from the back surface of the above-mentioned base10, as shown inFIG. 1B. The protruding portion of the substrate section E1is connected on the back side of the base10to, for example, a motherboard (not shown) and the like for the sending and the like of a signal to the optical element8.

In the above-mentioned optical sensor module, a light beam H is propagated in a manner to be described below. Specifically, when the above-mentioned optical element8is, for example, a light-emitting element, the light beam H emitted from the light-emitting portion of the optical element8passes through the transparent resin layer9and through the over cladding layer3, and thereafter enters each core2through the first end surface2aof each core2. Then, the light beam H travels through the interior of each core2in an axial direction. Then, the light beam H exits from a second end surface2bof each core2. Thereafter, the light beam H exits from the lens surface of the lens portion3bprovided in the second end portion of the over cladding layer3, with the divergence of the light beam H restrained by refraction through the lens portion3b.

On the other hand, when the above-mentioned optical element8is a light-receiving element, a light beam travels in a direction opposite from that described above, although not shown. Specifically, the light beam enters the lens surface of the lens portion3bprovided in the second end portion of the over cladding layer3, and enters each core2through the second end surface2bof each core2, while being narrowed down and converged by refraction through the lens portion3b. Then, the light beam travels through the interior of each core2in an axial direction. The light beam passes through and exits from the over cladding layer3, then passes through the transparent resin layer9, and is received by the light-receiving portion of the above-mentioned optical element8.

The above-mentioned optical sensor module is manufactured by undergoing the process steps (1) to (3) to be described below.

(1) The step of producing the above-mentioned optical waveguide section W1(with reference toFIGS. 4A to 4C, andFIGS. 5A to 5D).

(2) The step of producing the above-mentioned substrate section E1(with reference toFIGS. 7A to 7D).

(3) The step of coupling the above-mentioned substrate section E1to the above-mentioned optical waveguide section W1.

The above-mentioned step (1) of producing the optical waveguide section W1will be described. First, a substrate20of a flat shape (with reference toFIG. 4A) for use in the formation of the under cladding layer1is prepared. Examples of a material for the formation of the substrate20include glass, quartz, silicon, resin, metal and the like. In particular, a stainless steel substrate is preferable. This is because the stainless steel substrate is excellent in resistance to thermal expansion and contraction so that various dimensions thereof are maintained substantially at their design values in the course of the manufacture of the above-mentioned optical waveguide section W1. The thickness of the substrate20is, for example, in the range of 20 μm to 1 mm.

Then, as shown inFIG. 4A, a varnish prepared by dissolving a photosensitive resin such as a photosensitive epoxy resin and the like for the formation of the under cladding layer in a solvent is applied to a predetermined region of the surface of the above-mentioned substrate20. Thereafter, a heating treatment (at 50 to 120° C. for approximately 10 to 30 minutes) is performed on the varnish, as required, to dry the varnish, thereby forming a photosensitive resin layer1A for the formation of the under cladding layer1. Then, the photosensitive resin layer1A is exposed to irradiation light such as ultraviolet light and the like. This causes the photosensitive resin layer1A to be formed into the under cladding layer1. The thickness of the under cladding layer1is typically in the range of 1 to 50 μm.

Next, as shown inFIG. 4B, a photosensitive resin layer2A for the formation of the cores is formed on the surface of the above-mentioned under cladding layer1in a manner similar to the process for forming the above-mentioned photosensitive resin layer1A for the formation of the under cladding layer. Then, the above-mentioned photosensitive resin layer2A is exposed to irradiation light through a photomask formed with an opening pattern corresponding to the pattern of the cores2. Next, a heating treatment is performed. Thereafter, development is performed using a developing solution to dissolve away unexposed portions of the above-mentioned photosensitive resin layer2A, as shown inFIG. 4C, thereby forming the remaining photosensitive resin layer2A into the pattern of the cores2. The thickness (height) of the cores2is typically in the range of 5 to 60 μm. The width of the cores2is typically in the range of 5 to 60 μm.

A material for the formation of the above-mentioned cores2includes, for example, a photosensitive resin similar to that for the above-mentioned under cladding layer1, and the material used herein has a refractive index greater than that of the material for the formation of the above-mentioned under cladding layer1and the over cladding layer3(with reference toFIG. 5B). The adjustment of this refractive index may be made, for example, by adjusting the selection of the types of the materials for the formation of the above-mentioned under cladding layer1, the cores2and the over cladding layer3, and the composition ratio thereof.

Next, a molding die30(with reference toFIG. 5A) is prepared. This molding die30is used to die-mold the over cladding layer3(with reference toFIG. 5C) and the extensions4of the over cladding layer3which have the groove portions4afor the positioning of the substrate section (with reference toFIG. 5C) at the same time. The lower surface of this molding die30is formed with a recessed portion31having a die surface complementary in shape to the above-mentioned over cladding layer3, as shown inFIG. 5Athat is a perspective view as viewed from below. This recessed portion31includes portions31afor the formation of the above-mentioned extensions4, and a portion31bfor the formation of the lens portion3b(with reference toFIG. 5C). Ridges32for the molding of portions of the groove portions4afor the positioning of the above-mentioned substrate section which correspond to the over cladding layer3are formed in the portions31afor the formation of the extensions. Also, the upper surface of the above-mentioned molding die30is formed with alignment marks (not shown) for the purpose of alignment with the first end surfaces2a(the right-hand end surface as seen inFIG. 5B) of the cores2for the appropriate positioning of the molding die30when in use. The above-mentioned recessed portion31and the ridges32are formed in appropriate positions with respect to the alignment marks.

Thus, when the above-mentioned molding die30is set after the alignment marks of the above-mentioned molding die30are aligned with the first end surfaces2aof the respective cores2, and is used to perform the molding in that state, the over cladding layer3and the groove portions4afor the positioning of the substrate section are die-molded at the same time in appropriate positions with respect to the first end surfaces2aof the respective cores2. Also, the above-mentioned molding die30is set by bringing the lower surface of the molding die30into intimate contact with the surface of the under cladding layer1, whereby the space surrounded by the die surfaces of the above-mentioned recessed portion31, the surface of the under cladding layer1and the surfaces of the cores2is defined as a mold space33. Further, the above-mentioned molding die30is further formed with an inlet (not shown) for the injection of a resin for the formation of the over cladding layer therethrough into the above-mentioned mold space33, the inlet being in communication with the above-mentioned recessed portion31.

An example of the above-mentioned resin for the formation of the over cladding layer includes a photosensitive resin similar to that for the above-mentioned under cladding layer1. In this case, it is necessary that the photosensitive resin that fills the above-mentioned mold space33be exposed to irradiation light such as ultraviolet light and the like directed through the above-mentioned molding die30. For this reason, a molding die made of a material permeable to the irradiation light (for example, a molding die made of quartz) is used as the above-mentioned molding die30. It should be noted that a thermosetting resin may be used as the resin for the formation of the over cladding layer. In this case, the above-mentioned molding die30may have any degree of transparency. For example, a molding die made of metal or quartz is used as the above-mentioned molding die30.

Then, as shown inFIG. 5B, the alignment marks of the above mentioned molding die30are aligned with the first end surfaces2aof the above-mentioned cores2so that the entire molding die30is appropriately positioned. In this state, the lower surface of the molding die30is brought into intimate contact with the surface of the under cladding layer1. Then, the resin for the formation of the over cladding layer is injected through the inlet formed in the above-mentioned molding die30into the mold space33surrounded by the die surfaces of the above-mentioned recessed portion31and the ridges32, the surface of the under cladding layer1and the surfaces of the cores2to fill the above-mentioned mold space33therewith. Next, when the resin is the photosensitive resin, exposure to irradiation light such as ultraviolet light is performed through the above-mentioned molding die30, and thereafter a heating treatment is performed. When the above-mentioned resin is the thermosetting resin, a heating treatment is performed. This hardens the above-mentioned resin for the formation of the over cladding layer to form the groove portions4afor the positioning of the substrate section (the extensions4of the over cladding layer3) at the same time as the over cladding layer3. When the under cladding layer1and the over cladding layer3are made of the same material, the under cladding layer1and the over cladding layer3are integrated together at the contact portions thereof. Then, the molding die30is removed. As shown inFIG. 5C, the over cladding layer3and the portions of the groove portions4afor the positioning of the substrate section which correspond to the over cladding layer3are provided. The portions of the groove portions4afor the positioning of the substrate section are positioned in an appropriate location relative to the first end surfaces2aof the cores2because these portions are formed with respect to the first end surfaces2aof the cores2by using the above-mentioned molding die30, as mentioned earlier. Also, the lens portion3bof the above-mentioned over cladding layer3is also positioned in an appropriate location. Thus, the formation of the portions of the groove portions (fitting portions)4afor the positioning of the substrate section in the appropriate position relative to the first end surfaces2aof the cores2in the optical waveguide section W1is one of the striking characteristics of the present invention.

The thickness of the above-mentioned over cladding layer3(the thickness as measured from the surface of the under cladding layer1) is typically in the range greater than the thickness of the cores2and not greater than 1200 μm. The size of the above-mentioned groove portions4afor the positioning of the substrate section is defined in corresponding relation to the size of the fitting plate portions5aof the substrate section E1for fitting engagement therewith. For example, the depth of the grooves is in the range of 0.2 to 1.2 mm, and the width of the grooves is in the range of 0.2 to 2.0 mm.

Then, as shown inFIG. 5D, the substrate20is stripped from the back surface of the under cladding layer (see the arrow shown). At this time, portions1bof the under cladding layer1where the over cladding layer3is absent, such as portions1aof the under cladding layer1corresponding to the above-mentioned groove portions4aof the over cladding layer3, have no adhesion to the over cladding layer3, and hence are generally stripped off (together with the substrate20) while adhering to the substrate20. The remaining portion of the under cladding layer1is kept bonded to the over cladding layer3, and separation occurs between the back surface of the under cladding layer1and the substrate20. At this time, the portions1aof the under cladding layer1corresponding to the above-mentioned groove portions4aare stripped off and removed together with the above-mentioned substrate20. Thus, the groove portions4afor the positioning of the substrate section are formed to extend across the thickness of the under cladding layer1and the over cladding layer3. This provides the optical waveguide section W1including the under cladding layer1, the cores2and the over cladding layer3, and formed with the groove portions4afor the positioning of the above-mentioned substrate section. In this manner, the above-mentioned step (1) of producing the optical waveguide section W1is completed.

Then, as shown inFIG. 6, the above-mentioned optical waveguide section W1is bonded onto the base10that is an acrylic board or the like with the adhesive layer11therebetween. At this time, the under cladding layer1is bonded onto the base10with the adhesive layer11. A base having no irregularities on the surface thereof is used as the above-mentioned base10. The base10may be of any material, and may have any degree of transparency and any thickness. Examples of the base10include a polypropylene (PP) board, a metal plate, a ceramic sheet, and the like. The thickness of the above-mentioned base10is, for example, in the range of 500 μm to 5 mm.

Next, the above-mentioned step (2) of producing the substrate section E1will be described. First, a substrate5A (with reference toFIG. 7A) serving as a base material of the above-mentioned shaping substrate5is prepared. Examples of a material for the formation of the substrate5A include metal, resin and the like. In particular, a stainless steel substrate is preferable from the viewpoint of easy processibility and dimensional stability. The thickness of the above-mentioned substrate5A is, for example, in the range of 0.02 to 0.1 mm.

Then, as shown inFIG. 7A, a varnish prepared by dissolving a photosensitive resin for the formation of the insulation layer such as a photosensitive polyimide resin and the like in a solvent is applied to a predetermined region of the surface of the above-mentioned substrate5A. Thereafter, a heating treatment is performed on the varnish, as required, to dry the varnish, thereby forming a photosensitive resin layer for the formation of the insulation layer. Then, the photosensitive resin layer is exposed to irradiation light such as ultraviolet light and the like through a photomask. This causes the photosensitive resin layer to be formed into the insulation layer6having a predetermined shape. The thickness of the insulation layer6is typically in the range of 5 to 15 μm.

Next, as shown inFIG. 7B, the optical element mounting pad7and the electric circuit (not shown) for connection to the optical element mounting pad7are formed on the surface of the above-mentioned insulation layer6. The formation of the mounting pad (including the electric circuit)7is achieved, for example, in a manner to be described below. Specifically, a metal layer (having a thickness on the order of 60 to 260 nm) is initially formed on the surface of the above-mentioned insulation layer6by sputtering, electroless plating or the like. This metal layer becomes a seed layer (a layer serving as a basis material for the formation of an electroplated layer) for a subsequent electroplating process. Then, a dry film resist is affixed to the opposite surfaces of a laminate comprised of the above-mentioned substrate5A, the insulation layer6, and the seed layer. Thereafter, a photolithographic process is performed to form hole portions having the pattern of the above-mentioned mounting pad7in the dry film resist on the side where the above-mentioned seed layer is formed, so that surface portions of the above-mentioned seed layer are uncovered at the bottoms of the hole portions. Next, electroplating is performed to form an electroplated layer (having a thickness on the order of 5 to 20 μm) in a stacked manner on the surface portions of the above-mentioned seed layer uncovered at the bottoms of the above-mentioned hole portions. Then, the above-mentioned dry film resist is stripped away using an aqueous sodium hydroxide solution and the like. Thereafter, a seed layer portion on which the above-mentioned electroplated layer is not formed is removed by soft etching, so that a laminate portion comprised of the remaining electroplated layer and the underlying seed layer is formed into the mounting pad (including the electric circuit)7.

Then, as shown inFIG. 7C, the above-mentioned substrate5A is formed into the shaping substrate5having the fitting plate portions5ain the appropriate position relative to the mounting pad7. The formation of the shaping substrate5is achieved, for example, in a manner to be described below. Specifically, the back surface of the above-mentioned substrate5A is covered with a dry film resist. A photolithographic process is performed to leave portions of the dry film resist having an intended shape unremoved so that the fitting plate portions5aare formed in the appropriate position relative to the mounting pad7. Then, uncovered portions of the substrate5A except where the portions of the dry film resist are left unremoved are etched away by using an aqueous ferric chloride solution. This causes the above-mentioned substrate5A to be formed into the shaping substrate5having the fitting plate portions5a. Then, the above-mentioned dry film resist is stripped away using an aqueous sodium hydroxide solution and the like. The size of the fitting plate portions5aof the above-mentioned shaping substrate5is, for example, as follows: a vertical dimension L1in the range of 0.5 to 5.0 mm; and a horizontal dimension (protrusion length) L2in the range of 0.5 to 5.0 mm. Thus, the formation of the fitting plate portions (to-be-fitted portions)5ain the appropriate position relative to the mounding pad7in the substrate section E1is one of the striking characteristics of the present invention.

Then, as shown inFIG. 7D, the optical element8is mounted on the mounting pad7, and thereafter the above-mentioned optical element8and its surrounding portion are sealed with a transparent resin by potting. The mounting of the above-mentioned optical element8is performed using a mounting machine after the optical element8is precisely positioned relative to the mounting pad7by using a positioning device such as a positioning camera and the like provided in the mounting machine. This provides the substrate section E1including the shaping substrate5having the fitting plate portions5a, the insulation layer6, the mounting pad7, the optical element8, and the transparent resin layer9. In this manner, the above-mentioned step (2) of producing the substrate section E1is completed. In the substrate section E1, the fitting plate portions5aare formed with respect to the mounting pad7, as mentioned earlier. Accordingly, the optical element8mounted on the mounting pad7and the fitting plate portions5aare in an appropriate positional relationship.

Next, the above-mentioned step (3) of coupling the optical waveguide section W1and the substrate section E1together will be described. Specifically, the fitting plate portions5ain the above-mentioned substrate section E1are brought into fitting engagement with the groove portions4ain the optical waveguide section W1for the positioning of the substrate section so that the surface (the light-emitting portion or the light-receiving portion) of the optical element8of the substrate section E1(with reference toFIGS. 3 and 7D) faces toward the first end surfaces2aof the cores2of the optical waveguide section W1(with reference toFIG. 6), whereby the above-mentioned optical waveguide section W1and the substrate section E1are integrated together (with reference toFIGS. 1A,1B and2). At this time, the lower edges of the fitting plate portions5aare placed into abutment with the surface of the base10. It should be noted that the fitting engagement portions of the above-mentioned groove portions4aand the fitting plate portions5amay be fixed with an adhesive. In this manner, the intended optical sensor module is completed.

In the above-mentioned optical waveguide section W1, as mentioned earlier, the first end surfaces2aof the cores2and the groove portions4afor the positioning of the substrate section are in an appropriate positional relationship. In the substrate section E1with the above-mentioned optical element8mounted therein, the optical element8and the fitting plate portions5afor fitting engagement with the above-mentioned groove portions4aare also in an appropriate positional relationship. As a result, in the above-mentioned optical sensor module provided by bringing the above-mentioned fitting plate portions5ainto fitting engagement with the above-mentioned groove portions4a, the first end surfaces2aof the cores2and the optical element8are automatically placed in an appropriate positional relationship without any alignment operation. This enables the above-mentioned optical sensor module to achieve the appropriate propagation of light. Thus, bringing the fitting plate portions (to-be-fitted portions)5ain the above-mentioned substrate section E1into fitting engagement with the groove portions (fitting portions)4ain the optical waveguide section W1for the positioning of the substrate section to appropriately position the first end surfaces2aof the cores2and the optical element8relative to each other is one of the striking characteristics of the present invention.

The above-mentioned optical sensor module according to the present invention may be used as a detection means for detecting a finger touch position and the like on a touch panel. This is done, for example, by forming two L-shaped optical sensor modules S1and S2and using the two L-shaped optical sensor modules S1and S2arranged in the form of a rectangular frame, as shown inFIG. 8. The first L-shaped optical sensor module S1is configured such that two substrate sections E1with respective light-emitting elements8amounted therein are in fitting engagement with a corner portion thereof, and such that the second end surfaces2bof the cores2and the lens surface of the over cladding layer3from which light beams H are emitted face toward the inside of the above-mentioned frame. The second L-shaped optical sensor module S2is configured such that a single substrate sections E1with a light-receiving elements8bmounted therein is in fitting engagement with a corner portion thereof, and such that the lens surface of the over cladding layer3and the second end surfaces2bof the cores2which receive the light beams H face toward the inside of the above-mentioned frame. The above-mentioned two L-shaped optical sensor modules S1and S2are arranged along the rectangle of the periphery of a display screen of a rectangular display D of the touch panel so as to surround the display screen, so that the light beams H emitted from the first L-shaped optical sensor module S1are received by the second L-shaped optical sensor module S2. This allows the above-mentioned emitted light beams H to travel in parallel with the display screen and in a lattice form on the display screen of the display D. When a portion of the display screen of the display D is touched with a finger, the finger blocks some of the emitted light beams H. Thus, the light-receiving element8bsenses a light blocked portion, whereby the position of the above-mentioned portion touched with the finger is detected. InFIG. 8, the cores2are indicated by broken lines, and the thickness of the broken lines indicates the thickness of the cores2. Also, the number of cores2is shown as abbreviated.

FIG. 9Ais a plan view schematically showing an optical sensor module according to a second embodiment of the present invention, andFIG. 9Bis a sectional view taken along the line B-B ofFIG. 9A.FIG. 10is a perspective view showing a first end portion (the right-hand end portion as seen inFIGS. 9A and 9B) of the optical sensor module as seen diagonally from the upper right. This optical sensor module is constructed by: individually producing an optical waveguide section W2including protruding portions (fitting portions)3afor the positioning of a substrate section, and a substrate section E2including through hole portions (to-be-fitted portions)50afor fitting engagement with the protruding portions3a; and then bringing the above-mentioned through hole portions50ain the substrate section E2into fitting engagement with the above-mentioned protruding portions3ain the above-mentioned optical waveguide section W2to integrate the substrate section E2and the optical waveguide section W2together. In the optical waveguide section W2, the above-mentioned protruding portions3aare formed in an appropriate position relative to the first end surfaces2aof the respective cores2. The optical element8is mounted in the substrate section E2, and the above-mentioned through hole portions50ahaving an appropriate shape are formed in an appropriate position relative to the optical element8. Thus, the first end surfaces2aof the respective cores2and the optical element8are appropriately positioned and in alignment with each other by the fitting engagement between the above-mentioned protruding portions3aand the through hole portions50a. In the optical waveguide section W2according to this embodiment, the first end portion (the right-hand end portion as seen inFIG. 9B) of the over cladding layer3is thick. The remaining parts of the second embodiment are similar to those of the first embodiment described above. Like reference numerals and characters are used to designate similar parts.

Specifically, in the above-mentioned optical waveguide section W2, the two protruding portions3aserving as the fitting portions for the positioning of the substrate section are provided on the upper surface of the over cladding layer3and are arranged in a direction in which the cores2are arranged (along the X-axis) while being appropriately positioned relative to the first end surfaces2aof the cores2.

The above-mentioned optical waveguide section W2is produced using a molding die40for the formation of the over cladding layer in the step of forming the over cladding layer, the molding die40being configured such that indentations42complementary in shape to the above-mentioned protruding portions3aare formed in a recessed portion41having a die surface complementary in shape to the over cladding layer3, as shown inFIG. 11that is a sectional view of the molding die40. The remaining steps for the production of the optical waveguide section W2in the second embodiment are similar to those for the production of the optical waveguide section W1in the first embodiment described above.

The above-mentioned substrate section E2employs a shaping substrate50including the two through hole portions50afor fitting engagement with the above-mentioned protruding portions3a, and abutment plate portions50bprotruding both leftwardly and rightwardly in cross direction as seen in the Figure for abutment with the surface of the above-mentioned base10, as shown inFIG. 12that is a perspective view of the substrate section E2. The through hole portions50aand the rectangular abutment plate portions50bprotruding leftwardly and rightwardly in cross direction as seen in the Figure in the above-mentioned shaping substrate50are formed by etching, and are appropriately positioned and shaped relative to the above-mentioned optical element mounting pad7.

The above-mentioned substrate section E2is produced by leaving portions of the dry film resist of an intended shape by a photolithographic process, and then etching away the uncovered portions of the substrate5A except where the portions of the dry film resist are left (with reference toFIG. 7C) in a manner similar to the production of the substrate section E1of the first embodiment described above, so that the through hole portions50aand the abutment plate portions50bare formed in appropriate positions relative to the mounting pads7in the step of forming the shaping substrate50by etching. The remaining steps for the production of the substrate section E2in the second embodiment are similar to those for the production of the substrate section E1in the first embodiment described above. It should be noted that the inside diameter of the through hole portions50ais slightly greater than the outside diameter of the protruding portions3a.

The process of coupling the optical waveguide section W2and the substrate section E2together to form the optical sensor module is performed by bringing the through hole portions50ain the substrate section E2into fitting engagement with the protruding portions3ain the optical waveguide section W2(the positioning along the X-axis) so that the surface (the light-emitting portion or the light-receiving portion) of the optical element8of the substrate section E2is opposed to the first end surfaces2aof the cores2, and also by placing the lower edges of the abutment plate portions50bof the substrate section E2into abutment with the surface of the base10(the positioning along the Y-axis). At this time, the substrate section E2is bent, as appropriate, and an outside portion of the substrate section E2is fixed on the surface of the base10with a fixing member12such as an adhesive, a protrusion and the like. When the substrate section E2is bent in this manner, the flexure of the substrate section E2accommodates variations in precision.

In the optical sensor module according to the second embodiment, the protruding portions3ain the optical waveguide section W2is preferably formed in a frusto-conical shape. The formation of the protruding portions3ain a frusto-conical shape allows the above-mentioned protruding portions3aand the through hole portions50ato come into coaxially fitting engagement with each other even if the outside diameter of the above-mentioned protruding portions3aand the inside diameter of the above-mentioned through hole portions50adeviate from their design values during the fitting engagement of the through hole portions50ain the substrate section E2with the protruding portions3a. This prevents misregistration between the optical waveguide section W2and the substrate section E2along a plane perpendicular to the axes thereof. When the protruding portions3ahave a frusto-conical shape, the size of the protruding portions3ais as follows: a height of 500 to 1200 μm, a lower base with a diameter of 800 to 3000 μm, and an upper base with a diameter of 500 to 2000 μm.

Also, the above-mentioned through hole portions50ain the substrate section E2are preferably in the form of slots extending in a direction perpendicular to a direction in which the through hole portions50aare arranged. When the through hole portions50aare in the form of slots, the slots accommodate variations in precision in the longitudinal direction thereof.

For the die-molding of the over cladding layer (including the groove portions4aand the protruding portions3a)3in the above-mentioned embodiments, the molding die30is set, and thereafter the resin is injected into the mold space33. Instead, the die-molding may be accomplished by press molding using the above-mentioned molding die30. Specifically, a resin layer is formed in a region where the over cladding layer3is to be formed so as to cover the cores2. The above-mentioned molding die30is pressed against the resin layer. In that state, exposure to irradiation light and a heating treatment may be performed through the above-mentioned molding die30.

In the above-mentioned embodiments, the insulation layer6is formed for the production of the substrate sections E1and E2. This insulation layer6is provided for the purpose of preventing a short circuit from occurring between the substrate5A having electrical conductivity such as a metal substrate and the mounting pad7. For this reason, when the substrate5A has insulating properties, the mounting pad7may be formed directly on the above-mentioned substrate5A without the formation of the insulation layer6.

In the above-mentioned embodiments, the second end portion (the left-hand end portion as seen in theFIGS. 1B and 9B) of the over cladding layer3is formed as the lens portion3b. Instead, the second end portion of the over cladding layer3may be formed in a planar configuration, rather than as the lens portions3b, depending on the application of the optical sensor module.

Next, examples of the present invention will be described. It should be noted that the present invention is not limited to the examples.

EXAMPLES

Material for Formation of Under Cladding Layer and Over Cladding Layer (Including Extensions and Protruding Portions)

A material for the formation of an under cladding layer and an over cladding layer was prepared by mixing35parts by weight of bisphenoxyethanolfluorene diglycidyl ether (component A), 40 parts by weight of 3′,4′-epoxycyclohexyl methyl-3,4-epoxycyclohexane carboxylate which is an alicyclic epoxy resin (CELLOXIDE 2021P manufactured by Daicel Chemical Industries, Ltd.) (component B), 25 parts by weight of (3′4′-epoxycyclohexane)methyl-3′,4′-epoxycyclohexyl-carboxylate (CELLOXIDE 2081 manufactured by Daicel Chemical Industries, Ltd.) (component C), and 2 parts by weight of a 50% by weight propione carbonate solution of 4,4′-bis[di(β-hydroxyethoxy)phenylsulfinio]phenyl-sulfide-bis-hexafluoroantimonate (component D).

Material for Formation of Cores

A material for the formation of cores was prepared by dissolving 70 parts by weight of the aforementioned component A, 30 parts by weight of 1,3,3-tris{4-[2-(3-oxetanyl)]butoxyphenyl}butane and one part by weight of the aforementioned component D in ethyl lactate.

Production of Optical Waveguide Section

The material for the formation of the above-mentioned under cladding layer was applied to a surface of a stainless steel substrate with an applicator. Thereafter, exposure by the use of irradiation with ultraviolet light (having a wavelength of 365 nm) at 2000 mJ/cm2was performed, to thereby form the under cladding layer (having a thickness of 25 μm) (with reference toFIG. 4A).

Then, the material for the formation of the above-mentioned cores was applied to a surface of the above-mentioned under cladding layer with an applicator. Thereafter, a drying process was performed at 100° C. for 15 minutes to form a photosensitive resin layer (with reference toFIG. 4B). Next, a synthetic quartz chrome mask (photomask) formed with an opening pattern identical in shape with the pattern of the cores was placed over the photosensitive resin layer. Then, exposure by the use of irradiation with ultraviolet light (having a wavelength of 365 nm) at 4000 mJ/cm2was performed by a proximity expo sure method from over the mask. Thereafter, a heating treatment was performed at 80° C. for 15 minutes. Next, development was carried out using an aqueous solution of γ-butyrolactone to dissolve away unexposed portions. Thereafter, a heating treatment was performed at 120° C. for 30 minutes to form the cores (having a thickness of 50 μm and a width of 50 μm) (with reference toFIG. 4C).

Next, a molding die made of quartz (with reference toFIG. 5A) for the die-molding of the over cladding layer and groove portions for the positioning of a substrate section (the extensions of the over cladding layer) at the same time was set in an appropriate position by using first end surfaces of the respective cores as a reference (with reference toFIG. 5B). Then, the material for the formation of the above-mentioned over cladding layer and the extensions thereof was injected into a mold space. Thereafter, exposure by the use of irradiation with ultraviolet light at 2000 mJ/cm2was performed through the molding die. Subsequently, a heating treatment was performed at 120° C. for 15 minutes. Thereafter, the die was removed. This provided the over cladding layer, and the groove portions for the positioning of the substrate section (with reference toFIG. 5C). The thickness of the above-mentioned over cladding layer (the thickness as measured from the surface of the under cladding layer) was 1000 μm when measured with a contact-type film thickness meter.

Then, the stainless steel substrate was stripped from the back surface of the under cladding layer (with reference toFIG. 5D). At this time, portions of the under cladding layer where the over cladding layer was absent, included in portions of the under cladding layer corresponding to the above-mentioned groove portions of the over cladding layer were stripped off while adhering to the stainless steel substrate (together with the stainless steel substrate). As a result, the groove portions were formed to extend across the thickness of the under cladding layer and the over cladding layer. Then, the stripped optical waveguide section was bonded onto an acrylic board with an adhesive (with reference toFIG. 6). The above-mentioned groove portions had the following dimensions: a depth of 1.0 mm, a width of 0.3 mm, and a distance of 14.0 mm between the bottom surfaces of opposed groove portions.

Production of Substrate Section

An insulation layer (having a thickness of 10 μm) made of a photosensitive polyimide resin was formed on a portion of the surface of a stainless steel substrate [25 mm×30 mm×35 μm (thick)] (with reference toFIG. 7A). Then, a semi-additive process was performed to form an optical element mounting pad (including an electric circuit) on a surface of the above-mentioned insulation layer, the optical element mounting pad being formed by lamination of a seed layer made of copper/nickel/chromium alloy, and an electro copper plated layer (having a thickness of 10 μm) (with reference toFIG. 7B).

Next, etching was performed using a dry film resist so that fitting plate portions were formed in an appropriate position relative to the above-mentioned optical element mounting pad. This caused the stainless steel substrate portion to be formed into a shaping substrate having the fitting plate portions. Thereafter, the above-mentioned dry film resist was stripped away using an aqueous sodium hydroxide solution (with reference toFIG. 7C).

A silver paste was applied to the surface of the above-mentioned optical element mounting pad. Thereafter, a high-precision die bonder (mounting apparatus) was used to mount a light-emitting element of a wire bonding type (SM85-1N001 manufactured by Optowell Co., Ltd.) onto the above-mentioned silver paste. Thereafter, a curing process was performed to harden the above-mentioned silver paste. Thereafter, the above-mentioned light-emitting element and its surrounding portion were sealed with a transparent resin (NT-8038 manufactured by Nitto Denko Corporation) by potting (with reference toFIG. 7D). In this manner, the substrate section was produced. The fitting plate portions of the substrate section had the following dimensions: a vertical dimension of 2.0 mm, a horizontal dimension (protrusion length) of 2.0 mm, and a total width of 14.0 mm.

Manufacture of Optical Sensor Module

The fitting plate portions in the above-mentioned substrate section were brought into fitting engagement with the groove portions in the above-mentioned optical waveguide section for the positioning of the substrate section, and the lower edges of the fitting plate portions were placed into abutment with the surface of the acrylic board. Thereafter, the fitting engagement portions of the fitting plate portions and the groove portions were fixed with an adhesive. In this manner, an optical sensor module was manufactured (with reference toFIGS. 1A,1B and2).

The optical waveguide section and the substrate section in Example 1 described above were produced in a manner to be described below. Except for this, an optical sensor module in Example 2 was manufactured in a manner similar to that in Example 1 described above.

Production of Optical Waveguide Section

The molding die for the formation of the over cladding layer was changed in the step of forming the over cladding layer. This produced an optical waveguide section in which two protruding portions formed in a frusto-conical shape for the positioning of the substrate section were provided on the upper surface of the over cladding layer and were arranged in a direction in which the cores were arranged while being appropriately positioned relative to the first end surfaces of the cores. The above-mentioned protruding portions of the frusto-conical shape had the following dimensions: a height of 0.8 mm, a lower base diameter of 1.4 mm, an upper base diameter of 2.0 mm, and a center-to-center distance of 5.0 mm between the two protruding portions.

Production of Substrate Section

The shape of the dry film resist was changed in the step of forming the shaping substrate by etching. This produced the shaping substrate in which rectangular abutment plate portions for abutment with the surface of the above-mentioned acrylic board protruded on opposite sides in an appropriate position relative to the optical element mounting pad and in which two through hole portions for fitting engagement with the protruding portions were formed (with reference toFIG. 12). The above-mentioned abutment plate portions had the following dimensions: a vertical dimension of 2.0 mm, a horizontal dimension (protrusion length) of 2.0 mm, and a total width of 14.0 mm. The above-mentioned through hole portions were in the form of slots having the following dimensions: an arcuate portion radius of 0.95 mm, a width of 1.90 mm, a length of 3.9 mm, and a center-to-center distance of 5.0 mm between the two slots.

Manufacture of Optical Sensor Module

The through hole portions in the above-mentioned substrate section were brought into fitting engagement with the protruding portions in the above-mentioned optical waveguide section for the positioning of the substrate section, and the lower edges of the abutment plate portions were placed into abutment with the surface of the acrylic board. Thereafter, the abutting portions of the abutment plate portions were fixed with an adhesive. In this manner, an optical sensor module was manufactured (with reference toFIGS. 9A,9B and10).

Light Propagation Test

Current was fed through the light-emitting element of the optical sensor module in Examples 1 and 2 described above to cause the light-emitting element to emit light. Then, the emission of light from an end portion of the optical sensor module was seen.

This result shows that the above-mentioned manufacturing method allows the optical sensor module obtained thereby to propagate light appropriately without any alignment operation of the cores of the optical waveguide section and the light-emitting element of the substrate section.

The optical sensor module according to the present invention may be used for a detection means for detecting a finger touch position and the like on a touch panel, or information communications equipment and signal processors for transmitting and processing digital signals representing sound, images and the like at high speeds.

Although specific forms of embodiments of the instant invention have been described above and illustrated in the accompanying drawings in order to be more clearly understood, the above description is made by way of example and not as a limitation to the scope of the instant invention. It is contemplated that various modifications apparent to one of ordinary skill in the art could be made without departing from the scope of the invention.