JP2010170606A - Method of manufacturing prism assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently manufacture a compact prism assembly of high accuracy when there is an optical thin film preventing the irradiation of a photosetting adhesive with light. <P>SOLUTION: A plurality of units 51a formed by superposing thin plates 41a and 41b to each other so that an optical thin film is interposed in a superposed surface on one transparent thick plate 42 are superposed and a photosetting adhesive is cured by irradiation with light to form a substrate joining body 51. The substrate joining body 51 is cut at a fixed pitch in a direction crossing each superposed surface of the substrate joining body at a fixed angle to form joining substrates in each of which a cut surface of the thick plate 42 and cut surfaces of the thin plates 41a and 41b by the cutting are exposed in a layer shape. The joining substrate is cut vertically with respect to the surface thereof along the cut surface of the thick plate 42 through the center of a part formed of the thick plate 42 to form a plurality of prismatic substrates. The prismatic substrate is cut vertically with respect to the longitudinal direction thereof at a fixed pitch to form each prism assembly. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a prism assembly in which a plurality of prisms are joined together, and more particularly to a method for producing a prism assembly having two or more prism joining surfaces.

  In recent years, optical drives compatible with a plurality of types of optical discs such as CDs, DVDs, and Blu-ray discs (BD) have become widespread. In an optical drive that supports a plurality of types of optical discs, it is required to share many parts of the optical pickup with each optical disc in order to reduce costs by reducing the number of parts, and to reduce the size and thickness. A prism assembly is known as a member used for such an optical pickup. The prism assembly is formed by joining a plurality of prisms through an optical thin film such as a polarization separation film or a reflection film. The optical path of the laser light incident on the optical disk or the optical path of the laser light reflected back to the optical disk is set for each optical disk. Used as a common member.

  The prism assembly is manufactured, for example, by molding each prism to be joined, forming an optical thin film necessary for each prism, and joining them. However, this method requires many man-hours for polishing at the stage of forming each prism constituting the prism assembly, and further requires many complicated steps such as attaching and peeling the prism material to the polishing jig. . In addition, when manufacturing prism assemblies by molding each prism and then bonding each prism, there is a limit to the miniaturization of each prism and the accuracy with which each prism can be bonded, which stabilizes the prism assembly with good optical performance. It is difficult to produce.

  For this reason, rather than pre-molding each prism constituting the prism assembly, a plurality of glass substrates with optical thin films formed on the surface are stacked and bonded, and then cut diagonally. A method of easily manufacturing a small prism assembly bonded with high accuracy is known (Patent Document 1).

  By the way, since inexpensive and quick and strong adhesive strength can be obtained, a photo-curing adhesive that is cured by irradiating ultraviolet rays is mainly used for joining the prism and the glass substrate as described above. . On the other hand, the BD that has been remarkably popular in recent years is an optical disk that uses blue light having a wavelength of about 405 nm, which is close to ultraviolet rays. Therefore, the prism assembly corresponding to the BD has a reflection film or a polarization separation film that reflects light in this wavelength band. Used.

  For this reason, when it is going to manufacture the prism assembly corresponding to BD with the manufacturing method of patent document 1 using the photocurable adhesive hardened | cured with an ultraviolet-ray, the reflection which prevents irradiation of an ultraviolet-ray on the glass substrate to pile up Since a film, a polarization separation film, etc. are provided, the amount of UV irradiation is insufficient after these optical thin films, and sufficient adhesive strength cannot be obtained, or a long time is required to obtain sufficient adhesive strength. Of ultraviolet rays will be required.

In this way, when there is an optical thin film that prevents the ultraviolet irradiation of the photocurable adhesive, the glass substrate is overlaid and bonded in units that do not prevent the ultraviolet irradiation of the photocurable adhesive. A method of manufacturing a prism assembly in the same manner as the manufacturing method described in Patent Document 1 has been proposed (Patent Document 2).
Japanese Patent No. 2639312 JP 2005-164982 A

  However, in the method of joining the surfaces that require high precision and strong bonding with the photo-curing adhesive, the application of the photo-curing adhesive and the irradiation of the ultraviolet rays that cure it are powerful with high precision. Therefore, there is a problem that the manufacturing process of the prism assembly becomes complicated and inefficient.

  In addition, if a plurality of glass substrates firmly bonded with a photo-curing adhesive is used as one unit and this is temporarily bonded with a peelable adhesive, two types of adhesive are used, which is stable. In order to manufacture a prism assembly of the quality described above, adjustment and management of the properties of each adhesive are complicated. In addition, using a plurality of adhesives is disadvantageous in terms of cost.

  Furthermore, in order to secure good optical performance of the manufactured prism assembly, it is necessary to cut and remove the temporarily bonded surfaces or to polish them. For this reason, the use of temporary bonding increases the number of cutting and polishing processes, making the prism assembly manufacturing process cumbersome and inefficient, and there are many parts that must be cut off by cutting and polishing, resulting in wasted material. Therefore, there is a problem that the cost of the prism assembly is increased.

  The present invention has been made in view of the above-mentioned problems, and a prism assembly capable of efficiently manufacturing a small and highly accurate prism assembly even when there is an optical thin film that prevents irradiation of a photocurable adhesive. It aims at providing the manufacturing method of.

  According to the prism assembly manufacturing method of the present invention, a laminated unit in which one or more thin transparent second substrates are superimposed on one thick transparent first substrate so that an optical thin film is interposed on the overlapping surface. A first step of superposing a plurality of units, and curing a photo-curing adhesive previously applied to each superposed surface by light irradiation to produce a substrate assembly, and each superposing surface of the substrate assembly; A second step of producing a bonded substrate in which the cut surface of the first substrate and the cut surface of the second substrate are exposed in layers on the front and back surfaces by the cutting in a direction intersecting at a constant angle; A third step of producing a plurality of prismatic substrates by cutting the bonding substrate perpendicularly to the surface along the cut surface of the first substrate so as to pass through the center of the portion made of the first substrate; The prismatic substrate in the longitudinal direction The first prism element obtained by cutting the first substrate vertically at a constant pitch and having the first prism element obtained at the both ends, and the second prism element obtained by cutting the second substrate between them is provided. And a fourth step of obtaining one or more prism assemblies.

  Further, in accordance with the certain angle at which the substrate bonded body is cut in the second step, the substrate bonded body is overlapped while shifting the positions of the first substrate and the second substrate stepwise in the first step. It is characterized by producing.

  Further, in the first step, when the photocurable adhesive is cured, light is irradiated from a direction parallel to the overlapping surface.

  Further, the substrate assembly is characterized in that a third substrate thicker than the second substrate is disposed at the uppermost and lowermost stages.

  The photo-curing adhesive is an ultraviolet-curing adhesive that is cured by ultraviolet rays.

  The substrate assembly is manufactured by disposing two or more first substrates on both sides of the second substrate, and the prism assembly is manufactured to have two or more second prism elements. Features.

  According to the present invention, even when there is an optical thin film that hinders irradiation of the photocurable adhesive, a highly accurate and small prism assembly can be efficiently manufactured.

  As shown in FIG. 1, an optical pickup 11 is an optical system for reading data from an optical disk 12, and is used in common for optical disks 12 having three different wavelength bands, CD, DVD, and BD. The optical pickup 11 includes a blue laser diode (hereinafter referred to as blue LD) 16, a red laser diode (hereinafter referred to as red LD) 17, a dichroic prism 18, a prism assembly 20, and a blue optoelectronic integrated circuit (hereinafter referred to as blue OEIC). 22, a red optoelectronic integrated circuit (hereinafter referred to as red OEIC) 23, and the like.

  The blue LD 16 is a laser diode that emits blue laser light having a wavelength of 405 nm, and is emitted when the optical disk 12 is a BD. The blue laser light emitted from the blue LD 16 is incident on a diffraction grating (not shown) provided in front of the blue LD 16 and branched into a main beam for data reading and two sub beams for tracking and focusing. The Then, the blue laser light that has passed through the diffraction grating becomes linearly polarized light whose polarization direction is adjusted to a predetermined direction by a half-wave plate (not shown) and enters the dichroic prism 18.

  The red LD 17 is a two-wavelength laser diode capable of emitting a red laser beam having a wavelength of about 650 nm and an infrared laser beam having a wavelength of about 780 nm. When the optical disk 12 is a CD or a DVD, the wavelength is selected and emitted. The The red LD 17 emits an infrared laser beam having a wavelength of about 780 nm when the optical disc 12 is a CD, and emits a red laser beam having a wavelength of about 650 nm when the optical disc 12 is a DVD.

  Laser light emitted from the red LD 17 is incident on a diffraction grating (not shown) provided in front of the red LD 17 and branched into a main beam for data reading and two sub beams for tracking and focusing. . Then, the red (infrared) laser light that has passed through the diffraction grating becomes linearly polarized light whose polarization direction is adjusted to a predetermined direction by a half-wave plate (not shown), and enters the dichroic prism 18.

  The dichroic prism 18 is provided with a color separation surface that transmits blue light and reflects red and infrared light at an angle of 45 degrees with respect to the optical axes of the blue LD 16 and the red LD 17. For this reason, the blue laser light incident from the blue LD 16 passes through the color separation surface and enters the prism assembly 20, and the red laser light and infrared laser light incident from the red LD 17 are reflected by the color separation surface, and the prism assembly. 20 is incident.

  The prism assembly 20 is a member in which a plurality of prisms are joined through various optical thin films, and unifies the optical paths of the infrared laser beam for CD, the red laser beam for DVD, and the blue laser beam for BD. . The prism assembly 20 includes four prisms, and a polarization separation film 31, a blue reflection film 32, and a red reflection film 33 are provided at the boundaries between the prisms. Further, in FIG. 1, for convenience of illustration, there is a space between the optical thin films 31, 32, 33 viewed from the optical axis direction of the LD 16, but the optical thin films 31, 32, 33 are viewed from the optical axis direction of the LD 16. Sometimes they do not overlap and they are placed without any gaps.

  The polarization separation film 31 transmits a polarization component in a predetermined direction and reflects a polarization component in a direction perpendicular to this direction. When the optical disk 12 is a BD, blue laser light is incident on the polarization separation film 31 from the blue LD 16, and when the optical disk 12 is a CD or a DVD, the red laser light and the infrared laser light are emitted from the red LD 17. The corresponding laser beam is incident.

  As described above, the laser light of each color incident on the polarization separation film 31 from the LDs 16 and 17 has a polarization direction in a direction in which the laser light is transmitted through the polarization separation film 31 by the half-wave plate provided in front of the LDs 16 and 17. Since the linearly polarized light is arranged, it passes through the polarization separation film 31. Thus, the laser light of each color transmitted through the polarization separation film 31 is a quarter wavelength plate that converts linearly polarized light into circularly polarized light, a collimator lens that converts the laser light into parallel light, and an optical axis that is bent in the direction of the optical disk 12. The light enters the optical disk 12 through a mirror and an objective lens (both not shown).

  On the other hand, the laser beam reflected by the optical disk 12 is incident on the polarization separation film 31. The laser light reflected and returned from the optical disk 12 thus rotates in the same direction as that incident on the optical disk 12 and is circularly polarized light whose traveling direction is reverse, so that it passes through the quarter-wave plate described above. Thus, the polarization direction is rotated by 90 degrees from the time of incidence on the optical disk 12. For this reason, the laser light reflected and returned from the optical disk 12 is reflected in the direction of the blue reflecting film 32 when entering the polarization separation film 31.

  The blue reflective film 32 reflects blue light and transmits red and infrared light. For this reason, when the optical disc 12 is a BD, the blue laser light reflected by the optical disc 12 is reflected in the order of the polarization separation film 31 and the blue reflection film 32, exits the prism assembly 20, and enters the blue OEIC 22. On the other hand, when the optical disk 12 is a DVD or a CD, the red (infrared) laser light reflected by the optical disk 12 is reflected by the polarization separation film 31 and then passes through the blue reflection film 32 to be red reflection film. 33 is incident.

  The red reflecting film 33 reflects the red laser beam for DVD and the infrared laser beam for CD. For this reason, when the optical disk 12 is a DVD or a CD, the red (infrared) laser light reflected by the optical disk 12 is reflected by the red reflecting film 33. Then, the red (infrared) laser light from the optical disk 12 is reflected by the mirror 34 and enters the red OEIC 23.

  The blue OEIC 22 is an integrated circuit in which a photoelectric conversion element and an electric circuit for processing an electric signal acquired by photoelectric conversion are integrally formed, and is connected to a blue LD 16 and an objective lens. Blue laser light from the optical disk 12 is incident on the blue OEIC 22 from the blue reflecting film 32 of the prism assembly 20. At this time, the blue OEIC 22 converts the data recorded on the optical disk 12 into an electrical signal by photoelectrically converting the main beam of the blue laser light, and acquires the electrical signal. At the same time, the blue OEIC 22 photoelectrically converts two types of sub-beams in the blue laser light, and acquires data such as the spot shape, spot direction, and beam intensity of each sub-beam. The blue OEIC 22 performs focusing control and tracking control by controlling the position of the objective lens based on the data obtained from such a sub beam. The blue OEIC 22 adjusts the output of the blue LD 16.

  Similar to the blue OEIC 22, the red OEIC 23 is an integrated circuit in which a photoelectric conversion element and an electric circuit for processing an electric signal acquired by photoelectric conversion are integrally formed. The red OEIC 23 is connected to the red LD 17 and the objective lens. Yes. Red (or infrared) laser light is incident on the red OEIC 23 from the red reflecting film 33 of the prism assembly 20 through the mirror 34. At this time, the red OEIC 23 acquires the data recorded on the DVD (or CD) from the main beam of the incident laser light as an electric signal in the same manner as the blue OEIC 22 described above. Further, similarly, the red OEIC 23 performs focusing control and tracking control based on data obtained from the sub beam, and adjusts the output of the red LD 17.

  The prism assembly 20 is a member used for the optical pickup 11 as described above, and has a rectangular parallelepiped shape as a whole as shown in FIG. 2 (A), and a transparent material as shown in FIG. 2 (B). It consists of four prisms 36, 37, 38, and 39.

  The prism 36 is a trapezoidal prism whose surface parallel to the optical axis of the blue LD 16 and the red LD 17 has a trapezoidal shape, and is joined to the prism 37 by an inclined surface 36a. The prism 37 is a parallelogram prism having a parallelogram shape whose plane parallel to the optical axes of the blue LD 16 and the red LD 17 is formed, and one side surface 37a is joined to the prism 36 and the other side surface parallel to the prism 36. 37 b is joined to the prism 38. A polarization separation film 31 is formed on the side surface 37 a bonded to the prism 36.

  The prism 38 is a parallelogram prism similar to the prism 37, and one side surface 38 a is bonded to the prism 37, and the other side surface 38 b parallel to this is bonded to the prism 39. A blue reflective film 32 is formed on the side surface 38a, and a red reflective film 33 is formed on the side surface 38b. The prism 39 is a trapezoidal prism similar to the prism 36, and is joined to the prism 38 at an inclined surface 39a.

  Further, a photo-curing adhesive that is cured by irradiating ultraviolet rays is used for joining the surfaces of the prisms 36, 37, 38, and 39, and the prisms 36, 37, 38, and 39 are sufficiently connected to each other. Bonded with sufficient strength.

  Hereinafter, a method for manufacturing the prism assembly 20 configured as described above will be described. As shown in FIGS. 3 to 6, a plurality of prism assemblies 20 are manufactured together. In manufacturing the prism assembly 20, as shown in FIGS. 3A to 3C, a glass substrate 41 (second substrate, hereinafter referred to as a thin plate) having a predetermined thickness and a thickness twice that of the substrate 41 are used. Two types of substrates, the above-described substrate 42 (first substrate, hereinafter referred to as a thick plate), are used. Each of the thin plate 41 and the thick plate 42 is made of a transparent material and is formed in a flat plate shape. The surfaces of the thin plate 41 and the thick plate 42 are both polished. The thickness of the thick plate 42 is determined in consideration of the cutting allowance in the third step (described later). In the following, it is assumed that the cutting allowance is sufficiently small, and the thickness of the thick plate 42 is 2 of the thin plate 41. It is assumed that it is twice as thick.

  When manufacturing the prism assembly 20, the thin plates 41 a and 41 b are produced from the thin plate 41 of these two types of substrates 41 and 42. The thin plates 41a and 41b have different optical thin films formed on the surfaces. First, as shown in FIG. 3A, the thin plate 41a is formed by forming the polarization separation film 31 on one surface of the thin plate 41. At the same time, as shown in FIG. 3B, the blue reflection film 32 is formed on one surface of the thin plate 41, and the red reflection film 33 is formed on the other surface, thereby producing the thin plate 41b.

  As shown in FIG. 4, the thin plates 41a and 41b on which various optical thin films are formed on the surface, and the thick plate 42 are periodically and stepped in the order of the thick plate 42, the thin plate 41b, and the thin plate 41a from the lower side. Then, the substrate bonded body 51 is manufactured by superimposing the substrates while shifting the positions in a certain direction (first step). Assuming that the unit assembly 51a (laminate unit) has a structure in which the thin plate 41b and the thin plate 41a are superposed on one thick plate 42, the substrate assembly 51 includes a plurality of units 51a. Overlapped structure. At this time, the substrates 41a, 41b, and 42 are overlapped so that any one of the polarization separation film 31, the blue reflection film 32, and the red reflection film 33 is disposed between the substrates 41a, 41b, and 42. Therefore, any one of the optical thin films among the polarization separation film 31, the blue reflection film 32, and the red reflection film 33 is interposed on the overlapping surface of each of the substrates 41a, 41b, and 42 of the substrate bonded body 51. . Further, an adhesive that bonds the substrates 41a, 41b, and 42 is applied between the substrates 41a, 41b, and 42 of the substrate bonded body 51 in advance. The adhesive used here is a photo-curing adhesive that cures when irradiated with ultraviolet rays. Further, the step-like positional deviation amount of each of the substrates 41a, 41b, and 42 is determined according to the angle at which the substrate bonded body 51 is cut when the bonded substrate 53 is cut to produce the bonded substrate 53. Here, the inclination of the stepped side surface of the substrate bonded body 51 is approximately 45 degrees.

  Then, the substrate bonded body 51 in a state where the substrates 41a, 41b, and 42 are overlapped via an adhesive is irradiated with ultraviolet rays to cure and bond the adhesive between the substrates 41a, 41b, and 42. At this time, if the substrate bonded body 51 is irradiated with ultraviolet rays only from a direction perpendicular to the surfaces of the substrates 41a, 41b, and 42, the polarization separation film 31 that prevents the substrate bonded body 51 from sufficiently transmitting ultraviolet rays. And the blue reflective film 32 are included, it is difficult for ultraviolet rays to reach the inside of the substrate assembly 51. For this reason, it is preferable that the ultraviolet rays irradiated to the substrate bonded body 51 are irradiated from the entire periphery of the substrate bonded body 51. In particular, it is preferable to irradiate ultraviolet rays at least from the side of the substrate assembly 51 so as to include a component 52 that enters the substrate assembly 51 from a direction parallel to the overlapping surface of the substrates 41a, 41b, and 42.

  When the substrate bonded body 51 is irradiated with ultraviolet rays in this way, the ultraviolet rays that have passed through the thick plate 42 located on the upper side are mainly irradiated to the bonding surface between the thin plate 41a and the thick plate 42 where the polarization separation film 31 is provided. . On this bonding surface, the glass substrate 41 of the thin plate 41a, the polarization separation film 31, the adhesive, and the thick plate 42 are superposed in this order from the lower side. For this reason, the joining surface of the thin plate 41a and the thick plate 42 is joined with sufficient strength without unevenness by the ultraviolet light that has entered from the side surface of the thick plate 42 located on the upper side of the thin plate 41a.

  Further, the bonding surface between the thin plate 41b and the thin plate 41a having the blue reflective film 32 is formed by the ultraviolet light attenuated by the polarization separation film 31 and the inside of the thick plate 42 positioned on the lower side of the thin plates 41a and 41b. As a result, the ultraviolet rays transmitted through the thin plate 41b are irradiated. Thereby, the joining surface of the thin plate 41a and the thin plate 41b is joined with sufficient strength without unevenness.

  Further, the ultraviolet rays that pass through the inside of the thick plate 42 located on the lower side of the thin plate 41 b are mainly irradiated to the joint surface between the thin plate 41 b and the thick plate 42 having the red reflecting film 33. In this joining surface, the glass substrate 41 of the thin plate 41b, the red reflecting film 33, the adhesive, and the thick plate 42 are superposed in this order from the upper side. For this reason, the ultraviolet ray which invaded from the side surface of the thick plate 42 located on the lower side is mainly irradiated to the joint surface between the thin plate 41b and the thick plate 42. Thereby, the joining surface of the thin plate 41a and the thick plate 42 is joined with sufficient strength without unevenness.

  After the substrates 41a, 41b and 42 of the substrate bonded body 51 are bonded in this way, as shown by broken lines in FIG. 5, the substrates 41a, 41b and 42 are aligned along the slopes of the substrates 41a, 41b and 42 which are bonded stepwise. , 41b, 42 are cut into layers at a constant pitch in a direction intersecting at a constant angle (here, 45 degrees) with the overlapping surfaces of the flat plate-like bonding substrates 53 (second step). ).

  The bonding substrate 53 includes a polarization separation film in which a layer-thickness portion 54 a made of the thick plate 42 and a thin-layer portion 54 b made of the thin plate 41 correspond to the stacking order of the substrates 41 a, 41 b, 42 in the substrate laminate 51. 31, a substrate periodically bonded via a blue reflecting film 32 and a red reflecting film 33. For this reason, the cut surfaces of the thin plates 41 a and 41 b and the cut surface of the thick plate 42 are exposed in layers on the front and back surfaces of the bonding substrate 53. The optical thin films 31, 32, and 33 in the bonding substrate 53 are inclined by a cutting inclination angle (45 degrees) with respect to the surface of the bonding substrate 53, which is a cut surface.

  Then, as shown by a broken line in FIG. 6, the bonding substrate 53 is cut perpendicularly to the surface along the cut surface of the thick plate 42 at a layer-thickness portion 54 a made of the thick plate 42, and has a plurality of corners. A columnar substrate 56 is produced (third step). At this time, the bonding substrate 53 is cut so as to pass through the center of the layer-thickness portion 54a made of the thick plate 42 when the side surface in which the cross section of each optical thin film appears periodically is seen.

  The prismatic substrate 56 manufactured in this way has a trapezoidal member 56a having a trapezoidal side surface according to the bonding order of the layer-thickness portion 54a and the layer-thin portion 54b in the bonding substrate 53. Four members, a parallelogram member 56b, a parallelogram member 56c, and a trapezoid member 56d, which are parallelograms, are joined to form a rectangular parallelepiped substrate as a whole. Further, the prismatic substrate 56 includes one each of three types of optical thin films, ie, a polarization separation film 31, a blue reflection film 32, and a red reflection film 33. The polarization separation film 31 is formed on the joint surface between the trapezoidal member 56a and the parallelogram member 56b. Further, the joint surface between the parallelogram member 56 b and the parallelogram member 56 c is the blue reflective film 32, and the joint surface between the parallelogram member 56 c and the trapezoid member 56 d is the red reflective film 33.

  Then, as shown in FIG. 7, the prism assembly 20 is manufactured by cutting the prismatic substrate 56 at a constant pitch perpendicular to the longitudinal direction (fourth step). When the prismatic substrate 56 is cut in this way, trapezoidal prisms 36 and 39 (first prism elements) obtained by cutting the thick plate 42 are at both ends, and the thin plates 41a and 41b are cut between them. The prism assembly 20 having the parallelogram prisms 37 and 38 (second prism elements) is manufactured.

  According to the manufacturing method of the prism assembly 20 described above, since a plurality of prism assemblies 20 can be manufactured together without individually forming the prisms, the cumulative tolerance of dimensions can be kept extremely small, and the prism assembly can be reduced. 20 can be manufactured accurately and efficiently. Further, it is possible to easily manufacture a small prism assembly 20 in which it is difficult to individually mold the prisms 36, 37, 38, and 39 constituting the prism assembly 20.

  In particular, in the manufacturing method of the prism assembly 20 described above, the substrate assembly 51 is not formed by superimposing only the substrates having the same thickness (for example, the thin plates 41a and 41b), but the thin plates 41a and 41b having a predetermined thickness are formed. Since the thicker plate 42 thicker than this is used in combination, when the substrates 41a, 41b, 42 constituting the substrate bonded body 51 are bonded with a photo-curing adhesive, the substrate bonded body 51 is exposed from the side surface of the thick plate 42. Ultraviolet rays are easy to enter inside. Thereby, even when the prism assembly 20 has an optical thin film that prevents the irradiation of ultraviolet rays, the bonding surfaces of the substrates 41a, 41b, and 42 can be reliably bonded at once by the photo-curing adhesive. Moreover, since the process of joining the board | substrate 41a, 41b, 42 in order or temporarily joining is not required, the accurate prism assembly 20 can be manufactured cheaply and easily.

  Furthermore, according to the manufacturing method of the prism assembly 20 described above, the size of the prism assembly 20 is the final product only by separating the substrate assembly 51, the bonded substrate 53, the prismatic substrate 56, and the prism assembly 20 in this order. It becomes the size. For this reason, the manufacturing method of the prism assembly 20 described above does not have an unnecessary cutting process or polishing process for adjusting the size of the final prism assembly 20, reducing the waste of materials generated here and reducing the cost of the prism. The assembly 20 can be manufactured.

  Further, in the manufacturing method of the prism assembly 20 described above, when the substrate bonded body 51 is manufactured, the substrates 41a, 41b, and 42 are joined in a step-like manner so that the substrate bonded body 51 is cut and bonded to the bonded substrate. The portion cut out from the end of each of the substrates 41a, 41b, 42 when manufacturing 53 is reduced.

  In the above-described embodiment, the example in which the prism assembly 20 includes the three optical thin films of the polarization separation film 31, the blue reflection film 32, and the red reflection film 33 has been described. The method for manufacturing a prism assembly described in the embodiment can be preferably applied to manufacture of a prism assembly including two or more optical thin films, and may be applied to manufacture of a prism including one optical thin film. The method for manufacturing a prism assembly described in the above-described embodiment is particularly effective when manufacturing a prism assembly that includes three or more optical thin films and that is particularly susceptible to light irradiation on the photocurable adhesive. . In this case, as in the above-described embodiment, two or more thin plates 41a and 41b are arranged on both sides of the thick plate 42 to produce the substrate assembly 51, and the prismatic substrate 56 is made of the thick plate 42. By cutting at a portion, three or more optical thin films are included in the prismatic substrate 56.

  In the above-described embodiment, when the substrate bonded body 51 is manufactured, the thick plate 42, the thin plate 41a, and the thin plate 41b are periodically overlapped in this order. In addition to superimposing 41a, 41b and 42, as shown in FIG. 8A, a glass substrate 61 (third film) on which no optical thin film is formed on the uppermost and lowermost layers of the substrate bonded body 51 is provided. Substrate), the glass substrate 61, the thin plate 41a, the thin plate 41b, the thick plate 42,... From the uppermost step, and the glass substrate 61, the thin plate 41b, the thin plate 41a, the thick plate 42,. It is preferable to arrange each substrate 41a, 41b, 42 and the glass substrate 61 so as to be. In this way, by arranging the glass substrates 61 at the uppermost and lowermost stages, as shown in FIG. 8B, the portion to be cut out when producing the prismatic substrate 56 from the extreme end of the bonding substrate 53, as shown in FIG. While reducing the amount of 62, the prismatic substrate 56 having the same configuration and shape as that manufactured from the central portion of the bonding substrate 53 can be manufactured.

  Thus, the thickness of the glass substrate 61 disposed at the uppermost and lowermost stages of the substrate bonded body 51 is preferably such that the portion 62 to be cut is as small as possible, and cut away as shown in FIG. It is preferable that the side surface of the portion 62 has a triangular shape, and the thickness is such that the portion 62 to be cut is minimized. For example, when manufacturing a prism assembly in which the optical thin films 31, 32, 33 are not overlapped with each other when viewed from the optical axis direction of the LD 16 and have no gap, and each prism 36 to 39 is configured to be minimum. The thickness of the glass substrate 61 is preferably 1.5 to 2 times the thickness of the thin plate 41. When the thickness of the glass substrate 16 is 1.5 times the thickness of the thin plate 41, the portion 62 to be cut is minimized, and the waste of material can be minimized. Further, when the thickness of the glass substrate 61 is twice that of the thin plate 41 (when the thick plate 42 is used as the glass substrate 61), only two types of the thin plate 41 and the thick plate 42 can be handled in the manufacture of the prism assembly 20. Therefore, the prism assembly 20 can be manufactured more easily.

  In the above-described embodiment, an example in which the polarization separation film 31 is provided on one surface of the thin plate 41a and the blue reflection film 32 and the red reflection film 33 are provided on each surface of the thin plate 41b has been described. The position where each optical thin film is provided in advance when manufacturing is not limited thereto. For example, the polarization separation film 31 formed on the surface of the thin plate 41 a in the above-described embodiment may be formed on one surface of the thick plate 42.

  In the above-described embodiment, the example in which the polarization separation film 31, the blue reflection film 32, and the red reflection film 33 are provided as the optical thin film has been described. However, the optical properties of the prism assembly 20 are not limited to this. Therefore, in addition to these optical thin films, it is preferable to provide other optical thin films such as an antireflection film. For example, in the above-described embodiment, the example in which the polarization separation film 31 is formed on one surface of the thin plate 41a and the optical thin film is not provided on the other surface has been described. However, the polarization separation film 31 is not provided. It is preferable to provide an antireflection film for preventing reflection of red laser light or infrared laser light on the surface.

  In the above-described embodiment, an example in which the optical thin film is not provided on the incident surface (and the emission surface) of the prism assembly 20 on which laser light is incident (emitted) has been described. It is preferable to provide an antireflection film on the surface. As described above, when the antireflection films are provided on the entrance surface and the exit surface of the prism assembly 20, the reflection is performed at an arbitrary timing as long as the bonded substrate 53 is formed and the surfaces corresponding to these are formed. A prevention film can be provided. For example, when the bonding substrate 53 is manufactured, antireflection films are provided on both the front and back surfaces of the bonding substrate 53. Thereafter, the bonding substrate 53 is cut in the same manner as in the above-described embodiment to produce a prismatic substrate 56 provided with an antireflection film on the front and back sides, and this is cut to form an antireflection film on the entrance surface and the exit surface. The prism assembly 20 provided with is manufactured. Further, for example, when the prismatic substrate 56 is manufactured, the prism assembly 20 may be manufactured by providing antireflection films on both the front and back surfaces of the prismatic substrate 56 and cutting the same in the same manner as in the above embodiment. Further, after the prism assembly 20 is manufactured in the same manner as in the above-described embodiment, an antireflection film may be provided on the entrance surface and the exit surface of each prism assembly 20. Even during the timing of providing these antireflection films, a homogeneous antireflection film can be provided efficiently and easily. Therefore, it is necessary to provide antireflection films on both the front and back surfaces of the bonding substrate 53 when the bonding substrate 53 is manufactured. Particularly preferred.

  In the above-described embodiment, an example in which a plurality of substrates 41a, 41b, and 42 are overlapped to create the substrate bonded body 51 has been described. However, the present invention is not limited to this, and the number of overlapping substrates 41a, 41b, and 42 is once. Depending on the amount of the prism assembly 20 to be manufactured, it may be arbitrarily determined. For example, when two prism assemblies 20 are produced in the longitudinal direction of the substrate laminate 51, the thin plate 41b, the thin plate 41a, the thick plate 42, the thin plate 41b, and the thin plate 41a are sequentially arranged from the lower stage side of the substrate bonded body 51. A single substrate may be used. However, the method for manufacturing the prism assembly 20 described in the above embodiment is particularly effective when the prism assembly 20 includes two or more optical thin films. For this reason, like the above-mentioned embodiment, when producing the substrate bonded body 51, it is preferable that the substrate bonded body 51 includes at least three or more substrates 41a, 41b, and 42 in total.

  In the above-described embodiment, the prism assembly 20 used in the optical pickup 11 has been described as an example. However, the use of the prism assembly 20 is not limited thereto. For this reason, the type of optical thin film provided in the prism assembly 20 is not limited to the polarization separation film 31, the blue reflection film 32, and the red reflection film 33 of the above-described embodiment, depending on the use of the prism assembly 20. A thin film of the nature can be provided.

  In the above-described embodiment, an example in which a photo-curing adhesive that is cured by ultraviolet rays is used when the substrates 41a, 41b, and 42 are bonded to produce the substrate bonded body 51 is described. Alternatively, a photo-curing adhesive that is cured by light having a wavelength band other than ultraviolet light may be used.

It is explanatory drawing which shows schematically the structure of the optical pick-up using a prism assembly. It is a perspective view which shows the structure of a prism assembly. It is explanatory drawing which shows the board | substrate used for manufacture of a prism assembly. It is explanatory drawing which shows the process of producing a board | substrate joined body. It is explanatory drawing which shows the process of producing a bonded substrate from a board | substrate bonded body. It is explanatory drawing which shows the process of producing a prismatic board | substrate from a joining board | substrate. It is explanatory drawing which shows the process of producing a prism assembly from a prismatic substrate. It is explanatory drawing which shows the preferable aspect of the uppermost stage and lowermost stage of a board | substrate bonded body when producing a board | substrate bonded body.

11 Optical pickup 12 Optical disc 16 Blue LD
17 Red LD
20 Prism assembly 22 Blue OEIC
23 OEIC for red
31 Polarization separation film 32 Blue reflection film 33 Red reflection film 36, 37, 38, 39 Prism 41, 41a, 41b Thin plate (second substrate)
42 Thick plate (first substrate)
51 substrate bonded body 53 bonded substrate 56 prismatic substrate

Claims (6)

A plurality of stacked unit units in which one or more thin transparent second substrates are superimposed on one thick transparent first substrate so that the optical thin film is interposed on the overlapping surface are overlapped, and each layer is overlapped. A first step of producing a substrate assembly by curing a photocurable adhesive previously applied to the mating surfaces by light irradiation;
Cutting is performed at a constant pitch in a direction intersecting each overlapping surface of the substrate assembly at a constant angle, and the cut surface of the first substrate and the cut surface of the second substrate are exposed in layers on the front and back surfaces by this cutting. A second step of manufacturing the bonded substrate,
A third step of producing a plurality of prismatic substrates by cutting the bonding substrate perpendicularly to the surface along the cut surface of the first substrate so as to pass through the center of the portion made of the first substrate; ,
The prismatic substrate is cut at a constant pitch perpendicular to the longitudinal direction, and the first prism element obtained by cutting the first substrate is provided at both ends, and the second substrate is cut between them. A fourth step of obtaining a prism assembly having one or more second prism elements obtained
A method of manufacturing a prism assembly comprising:   According to the fixed angle at which the substrate bonded body is cut in the second step, the substrate bonded body is manufactured by superimposing the first substrate and the second substrate while shifting the positions of the first substrate and the second substrate in the first step. The method of manufacturing a prism assembly according to claim 1.   3. The method of manufacturing a prism assembly according to claim 1, wherein when the photocurable adhesive is cured in the first step, light is irradiated from a direction parallel to the overlapping surface.   4. The method of manufacturing a prism assembly according to claim 1, wherein a third substrate thicker than the second substrate is disposed in the uppermost layer and the lowermost layer of the substrate bonded body. 5.   5. The method of manufacturing a prism assembly according to claim 1, wherein the photocurable adhesive is an ultraviolet curable adhesive that is cured by ultraviolet rays. 6.   The substrate assembly is manufactured by arranging two or more first substrates on both sides of the second substrate, and the prism assembly is manufactured by having two or more second prism elements. A method of manufacturing a prism assembly according to any one of claims 1 to 5.

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