JP2007163953A - Prism and method for manufacturing prism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prism in which an optical substrate is joined while keeping the quality of a hologram element. <P>SOLUTION: A recess having a depth larger than the thickness of a hologram element 100 is formed on a lower joint face 102a of a first prism L1. The recess is a space capable of housing the hologram element 100. A hologram photosensitive material sheet is stuck to a sticking face 102 in the recess and exposed/developed to form a hologram element 100. An adhesive AD is applied on joining faces of a second prism L2, and the first prism L1 is fitted/pressed to the second prism L2 to join. The inner perimeter of the recess 101 may be formed into a curved plane. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a prism in which a hologram element is interposed between the joint surfaces of a pair of optical substrates, and a method for manufacturing the prism.

  2. Description of the Related Art In recent years, a holographic optical element (hereinafter referred to as “hologram element”) is provided in a prism (optical substrate) such as glass, and a display device that projects an image to a user's eye via the hologram element. As examples of the display device, a glasses-type wearable display, a head-mounted display, and the like are known.

  The hologram element has two interference fringe patterns composed of interference fringes that are not parallel to the hologram substrate surface. The image projected from the display unit is reflected inside the prism to reach the hologram element, is diffracted and reflected by the interference fringe pattern of the hologram element, and is guided to the user's eyes.

A prism incorporating such a hologram element is manufactured as follows. First, a hologram element is formed on the joint surface of one of the pair of optical substrates. Then, an adhesive is applied to the bonding surface of the other optical substrate, and the two optical substrates are pressed and bonded so as to sandwich the hologram element (see, for example, Patent Document 1).
JP-A-8-36351

  By the way, when the optical substrate is bonded, if the bonding portion is not filled with sufficient adhesive, when external force is applied to the prism, stress concentration occurs in the portion where the adhesive is insufficiently filled, and the adhesive strength is reduced. There is a fear of causing a decline. In addition, air may be mixed between the bonding surface and the adhesive during bonding, which may reduce adhesive strength and hinder prism see-through performance. For this reason, it is necessary to perform an operation of filling the bonding portion with a sufficient amount of adhesive and then press-contacting to cause the excess adhesive to protrude and to remove the protruding adhesive.

  However, the hologram element is for projecting an image on the user's eyes by the diffraction action of the interference fringe pattern as described above, and it is necessary to maintain the quality and accuracy of the hologram element when the prism is manufactured. . However, since it is difficult to stabilize the gap amount between the optical substrates when the two optical substrates are pressed together as in Patent Document 1, if the gap amount is too small, the hologram element is optical. There was a problem that it was sandwiched between the substrates and damaged by the pressure at the time of pressure contact, and the quality and accuracy were lowered.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a prism in which an optical substrate is bonded while maintaining the quality and accuracy of a hologram element.

In order to solve the above problems, the invention described in claim 1
A prism in which a hologram element is interposed between the bonding surfaces of a pair of optical substrates,
A gap portion that can accommodate the hologram element is provided between the joint surfaces,
The hologram element is housed in the gap and the pair of optical base materials are bonded.

  According to a second aspect of the present invention, in the first aspect of the present invention, at least one of the optical base materials includes a concave portion having a depth greater than or equal to the thickness of the hologram element as the gap portion on the joint surface. It is characterized by that.

  According to a third aspect of the present invention, in the second aspect of the present invention, the inner periphery of the recess is a curved surface.

  According to a fourth aspect of the present invention, in the first aspect of the invention, at least one of the optical substrates has a height greater than or equal to the thickness of the hologram element on the joint surface, and the other optical substrate. It is characterized by including a protrusion that forms the gap by contacting the material at three or more points.

  The invention according to claim 5 is the invention according to claim 4, wherein the protrusion is curved.

  According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect, the other optical substrate that is in contact with the protruding portion has a hole into which the protruding portion can be fitted in the joint surface. It is a feature.

The invention described in claim 7
A method of manufacturing a prism in which a hologram element is interposed between the bonding surfaces of a pair of optical substrates,
Forming a gap between the joint surfaces capable of accommodating the hologram element; and
A joining step of housing the hologram element in the gap formed in the forming step and joining the pair of optical substrates;
It is characterized by including.

  According to the first and seventh aspects of the present invention, since the hologram element is housed and bonded to the gap between the bonding surfaces of the pair of optical substrates, the hologram element is bonded to the optical substrate at the time of bonding. It can be prevented from being pressed and damaged. Therefore, it is possible to provide a prism in which the optical base material is bonded while maintaining the quality and accuracy of the hologram element.

  According to the second aspect of the present invention, it is possible to obtain the same effect as that of the first aspect. By storing the hologram element in the concave portion having a depth greater than the thickness of the hologram element, the optical base can be obtained. It is possible to prevent the hologram element from being pressed and damaged by the optical base material at the time of joining the materials.

  According to the third aspect of the present invention, it is needless to say that the same effect as that of the second aspect of the invention can be obtained, and since the inner periphery of the concave portion is curved, the formation of the concave portion as the gap portion is possible. It becomes easy and it can prevent that air retains, when joining with adhesives etc.

  According to the invention described in claim 4, it is needless to say that the same effect as that of the invention described in claim 1 can be obtained, and the joining surface of one optical substrate has a height equal to or greater than the thickness of the hologram element. Since the gap is formed by the protrusion, it is possible to prevent the hologram element from being pressed and damaged by the optical substrate when the optical substrate is bonded.

  According to the fifth aspect of the present invention, it is needless to say that the same effect as that of the fourth aspect of the invention can be obtained. Since the protrusion is curved, the protrusion of the protrusion for forming the gap is formed. Formation is facilitated and air can be prevented from staying when bonding with an adhesive or the like.

  According to the invention described in claim 6, it is needless to say that the same effect as that of the invention described in claim 4 or 5 can be obtained, and the protrusion is formed on the joint surface of the other optical substrate with which the protrusion contacts. Since the hole which can fit is provided, positioning at the time of joining a pair of optical base materials becomes easy. Moreover, when joining with an adhesive agent etc., it can prevent that the position shift between optical base materials arises before the said adhesive agent hardens | cures.

Embodiment
Hereinafter, a method for manufacturing an eyepiece optical system (prism) in which a hologram element is interposed between the joint surfaces of a first prism and a second prism, which are a pair of optical base materials, will be described with reference to FIGS.

  First, FIG. 1 shows a manufacturing process of the eyepiece optical system P (see FIG. 4A). As shown in FIG. 1, the manufacturing process of the eyepiece optical system P includes a prism forming process S1 for forming and processing the first prism L1 and the second prism L2 into a predetermined shape, and the hologram element 100 on the first prism L1. A hologram forming step S3 to be formed and an integration step S5 for integrating the first prism L1 and the second prism L2, and the eyepiece optical system P shown in FIG. 5A is manufactured through these steps. .

  In the following description, the first prism L1 and the second prism L2 are collectively referred to as “prism”. For the sake of simplicity, the direction of the arrow Va shown in FIG. 2 is defined as the back direction and the direction of the arrow Vb is defined as the front direction with the surface of the eyepiece optical system P as a boundary. Hereinafter, each process of the manufacturing method of the eyepiece optical system P is demonstrated.

1. Prism Forming Step First, the prism forming step S1 will be described. The prism forming step S1 is a step of forming and processing the first prism L1 and the second prism L2 made of transparent resin or glass as shown in FIG. 2, and includes the first prism forming step S10 and the second prism. Forming step S12.

1.1 First Prism Formation Step In the first prism formation step S10, the first prism L1 is formed and processed by, for example, injection compression molding, cutting, polishing, or the like. FIG. 3A shows a front view of the first prism L1, and FIG. 3B shows an example of an AA cross-sectional view in FIG.

  The first prism L1 has a shape that can be fitted into the recessed portion 106 of the second prism L2, and is fitted into the recessed portion 106 of the second prism L2 on the lower and both sides of the external shape thereof. A joining surface to be joined when joining is formed. These joint surfaces include a lower joint surface 102a in the downward direction, a left joint surface 102b on the left side with respect to the front direction, and a right joint surface 102c on the right side. Has an open slope.

  A hologram element 100 is formed on the lower joint surface 102a in a hologram forming step S3 described later, and the inclination of the lower joint surface 102a is an angle at which image light can be guided to the user's eyes via the hologram element 100. It is formed.

  In addition, a rectangular recess 101 matching the shape of the hologram sensitive material is formed on the lower bonding surface 102a as a sticking surface of a hologram photosensitive material sheet (hereinafter abbreviated as “hologram sensitive material”). As a method for forming the recess 101, for example, a method of forming the recess 101 in advance by injection molding with a mold shaped like a recess, a method of processing the recess 101 by cutting the planar lower joint surface 102a, etc. Any known technique can be used as appropriate.

  The recess 101 is formed with a depth a (for example, 100 to 150 μm) equal to or greater than the thickness b of the hologram element 100 shown in FIG. As a result, a gap that can accommodate the hologram element 100 is formed. In a hologram forming step S3 to be described later, a hologram sensitive material is stuck in the concave portion 101 of the lower joint surface 102a to form the hologram element 100 (see FIG. 4).

1.2 Second Prism Formation Step In the second prism formation step S12, the second prism L2 is formed and processed by injection compression molding, cutting, polishing, or the like.

  The second prism L2 has a recessed portion 106 corresponding to the outer shape of the first prism L1 in the vicinity of the center thereof. On the inner periphery of the recess 106, there are a left joint surface 105b, a right joint surface 105c, and a lower joint surface 105a that are joined to the left joint surface 102b, the right joint surface 102c, and the lower joint surface 102a of the first prism L1, respectively. It is formed with an inclination that opens with respect to the back surface direction.

  In this way, by inclining the joint surfaces of the prisms, positioning when the first prism L1 is fitted into the recessed portion 106 of the second prism L2 is facilitated, and the first prism L1 is moved in the front direction. When force is applied, it can be prevented from coming out of the recess 106.

2. Hologram Forming Step Next, the hologram forming step S3 will be described. The hologram forming step S3 is a step of forming a hologram sensitive material on the concave portion 101 of the lower joint surface 102a of the first prism L1 to form the hologram element 100.

  The hologram photosensitive material is a gel-like sheet formed by containing a chemical composition such as a hologram photosensitive composition, a dye composition, and an exothermic endothermic composition, and a binder, and has a thickness of about 10 to 100 μm. It is comprised.

  In the hologram forming step S <b> 3, the hologram sensitive material is cut into a predetermined shape based on the rectangular region of the recess 101, and the cut hologram sensitive material is attached to the application surface 102. Then, the hologram photosensitive material stuck in the recess 101 is exposed with laser light, and developed by irradiating ultraviolet rays or the like. As a result, the hologram sensitive material reacts and shrinks to become a hologram element 100 having a thickness b of about 10 to 90 μm.

3. Integration Step Next, the integration step S5 will be described. The integration step S5 is a step in which the first prism L1 on which the hologram element 100 is formed in the hologram formation step S3 is combined and integrated with the second prism L2.

  In the integration step S5, as shown in FIG. 4, for example, a photocurable adhesive AD is applied to the lower joint surface 105a, the left joint surface 105b, and the right joint surface 105c of the second prism L2. Then, the first prism L1 is fitted into the recessed portion 106 of the second prism L2, and the left cemented surface 105b, the right cemented surface 105c, and the lower cemented surface 105a of the second prism L2 are connected to the first prism L1. It joins to each of the left joint surface 102b, the right joint surface 102c, and the lower joint surface 102a.

  At the time of joining, the first prism L1 and the second prism L2 are pressed against each other so that the adhesive AD protrudes from the joining portion. Then, after a certain period of time and a certain amount of light (for example, ultraviolet rays) are applied to the bonding surface to which the adhesive AD has been applied to cure the adhesive AD, the protruding adhesive AD is removed. Thereby, the eyepiece optical system P shown in FIG.

  FIG. 5B shows a BB cross-sectional view of the lower joint surfaces 102a and 105a of the first prism L1 and the second prism L2 that have undergone the integration step S5. As shown in FIG. 5B, the hologram element 100 is sandwiched and joined between the first prism L1 and the second prism L2, and the hologram element 100 has a depth a equal to or greater than its thickness b. Since it is formed in the recess 101 having, the second prism L2 is not contacted.

  As described above, according to the present embodiment, the first prism L1 and the second prism L2 are formed on the lower joint surface 102a in order to form the recess 101 that can accommodate the hologram element 100 having a depth a greater than the thickness b of the hologram element 100. The hologram element 100 can be prevented from coming into contact with the second prism L2 and being pressed when the two are pressed and joined. Thereby, since it is possible to prevent unnecessary pressure from being applied to the hologram element 100, damage to the hologram element 100 can be prevented and its quality can be maintained.

  Further, since it is possible to prevent the hologram element 100 from coming into contact with the lower joint surface 105a of the second prism L2, it is possible to press the prism without performing fine adjustment of force, and the work process of the integration step S5 Can be made easier.

[Modification]
The above-described embodiment is an example to which the present invention is applied, and the applicable range is not limited to the above-described one, and may be as follows.

  For example, in the first prism formation step S10, when the recess 101 is formed, in the above-described embodiment, the corner 108 where the inner surface 109 and the pasting surface 102 intersect is formed on the inner periphery of the recess 101. As shown in FIG. 6, the inner periphery of the recess 101 may be formed by a curved surface 102R. As a result, the formation of the recess 101 becomes easier than in the embodiment described above, and air can be prevented from staying in the inner periphery of the recess 101 when the adhesive is filled in the recess 101.

  In addition, the concave portion 101 is formed in the first prism L1, but it goes without saying that the same effect as that of the above-described embodiment can be obtained by forming the same concave portion 101 in the second prism L2.

  Further, by providing a protrusion 103 as shown in FIG. 7A on one prism, a gap that can accommodate the hologram element 100 may be formed. In this case, the concave portion 101 is not formed in the first prism forming step S10, and at least three protrusions 103 are formed on the lower joint surface 105a of the second prism L2 in the second prism forming step S12 with the same material as the prism. Form with.

  FIG. 7B is an example of a cross-sectional view taken along the line C-C when four protrusions 103 are provided and the first prism L1 is joined to the second prism L2 of FIG. As shown in FIG. 7A, the protrusion 103 has a height c that is equal to or greater than the thickness b of the hologram element 100, and is in contact with the first prism L1 at four points. Thereby, it is possible to prevent the hologram element 100 formed on the first prism L1 from being pressed against the second prism L2.

  Further, a fitting hole 107 into which the protrusion 103 can be fitted may be formed in the other prism of the prism provided with the protrusion 103. FIG. 8A is an example of a cross-sectional view of the prism when the protrusion 103 is provided in the second prism L2 and the fitting hole 107 is formed in the first prism L1. As shown in FIG. 8A, the protrusion 103 formed on the second prism L2 is fitted into the fitting hole 107 of the first prism L1 in the integration step S5. For this reason, positioning between the prisms in the integration step S5 is facilitated, and displacement of the prisms when the adhesive AD is cured can be prevented.

  Further, the protrusion 109 may be formed in a curved surface as shown in FIG. As a result, the processing and formation of the protrusion 109 can be facilitated, and air can be prevented from staying between the protrusion 109 and the lower bonding surface 105a. Further, the strength of the protrusion 109 can be increased, and the adjustment of the force at the time of pressing the prism can be simplified. Of course, the same effect can be obtained by forming the protrusions 103 and 109 on the first prism L1 side.

The flowchart for demonstrating the example of a manufacturing process of an eyepiece optical system. An example of the perspective view of a 1st prism and a 2nd prism. An example of (a) front view and (b) sectional view of the first prism. An example of the perspective view of the 1st prism and 2nd prism in an integration process. (A) An example of a perspective view of an eyepiece optical system, (b) An example of a sectional view of a first prism and a second prism. An example of sectional drawing of the 1st prism in a modification. (A) The front view of the 2nd prism in a modification, (b) An example of the 1st sectional view of the 1st prism and the 2nd prism. (A) 2nd sectional drawing of the 1st prism and 2nd prism in a modification, (b) An example of 3rd sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hologram element 101 Recessed part 102 Sticking surface 102a Lower joint surface 102R Curved surface 103 Projection part 106 Recessed part 107 Fitting hole AD Adhesive L1 First prism L2 Second prism P Eyepiece optical system S1 Prism formation process S10 First prism formation process S12 Second prism forming step S3 Hologram forming step S5 Integration step

Claims (7)

A prism in which a hologram element is interposed between the bonding surfaces of a pair of optical substrates,
A gap portion that can accommodate the hologram element is provided between the joint surfaces,
A prism characterized in that the hologram element is housed in the gap and the pair of optical base materials are bonded. At least one of the optical substrates is
2. The prism according to claim 1, wherein a concave portion having a depth greater than or equal to a thickness of the hologram element is provided as the gap portion on the joint surface.   The prism according to claim 2, wherein an inner periphery of the recess is a curved surface. At least one of the optical substrates is
2. A projection having a height greater than or equal to the thickness of the hologram element and forming the gap by contacting the other optical substrate at three or more points on the joint surface. The prism described in 1.   The prism according to claim 4, wherein the protrusion is curved. The other optical substrate in contact with the protrusion is
6. The prism according to claim 4 or 5, wherein the joint surface includes a hole into which the projection can be fitted. A method of manufacturing a prism in which a hologram element is interposed between the bonding surfaces of a pair of optical substrates,
Forming a gap between the joint surfaces capable of accommodating the hologram element; and
A joining step of housing the hologram element in the gap formed in the forming step and joining the pair of optical substrates;
The manufacturing method of the prism characterized by including.

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