JP3095434U - Fixing structure of diffraction grating and optical head device having the same - Google Patents

Abstract

(57) [Problem] To provide a diffraction grating fixing structure in which high positioning accuracy is easily realized in an optical head device. An optical head device includes a light source, a diffraction grating for splitting light emitted from the light source, and the diffraction grating.
And a leaf spring 40 for urging the diffraction grating 20 against the frame 30. The diffraction grating 20 is formed of a substantially cylindrical member having a first main surface 21a, a second main surface 21b, and a circumferential surface 23, and has a D-cut extending on the circumferential surface 23 in a direction intersecting the optical axis. It has a part 24. The frame 30 has first and second mounting surfaces 31a and 31b that cross each other and abut on the circumferential surface 23 of the diffraction grating 20. The leaf spring 40 includes the diffraction grating 20.
The diffraction grating 20 is inserted into the D-cut portion 24 in a direction intersecting the optical axis and abuts against the circumferential surface 23 of the diffraction grating 20, thereby connecting the diffraction grating 20 to the first and second mounting surfaces 31a and 31b.
And is urged toward.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

  The present invention relates to a fixed structure of a diffraction grating and an optical head device including the fixed structure.

[0002]

[Prior art]

  The optical head device is a disk-shaped recording medium (eg, CD (Compac t Disc) and DVD (Digital Versatile Disc). Hereafter, simply as an optical disc To tell. ) The information recording track is focused and the light beam is focused and run as a minute spot. It is a device that records and erases information by checking, and When playing back the information recorded on the Information is read by irradiating the recording track with a light beam and receiving the reflected light. It is a device to put out.

[0003]   Generally, in an optical head device, a so-called three-beam method is used for recording and reproducing information. Is used. As shown in FIG. 6, the three-beam method rotates the light emitted from the light source. The 0th order light (S1), the + 1st order diffracted light (S2) and the −1st order diffracted light (S 3), etc., and split it into a plurality of light beams, and illuminates the information recording track 10a of the optical disc 10. To shoot. Of the plurality of light fluxes arranged in a line, the zero-order light (S1) and Three light beams of ± first-order diffracted light (S2, S3) are applied in the extending direction of the information recording track 10a. Irradiate so as to intersect with, and the reflected light level of the + 1st-order diffracted light (S2) By performing servo control so that the reflected light level in (S3) is always equal to , The focus position of the 0th-order light (S1) located at the center is set at the center of the information recording track 10a. It becomes possible to keep. In FIG. 6, 10b indicates a guide track. No. 10c indicates a pit.

[0004]   FIG. 7 shows a dual light source type optical head having light sources corresponding to a CD and a DVD. It is a schematic diagram which shows the structure of an apparatus. When a CD is set as the optical disc 10 As shown in FIG. 7, the light emitted from the CD laser diode 1 is diffracted. The light is diffracted by the grating 3 and split into a plurality of light beams. The split light is the beam split. Transmitted through the lasers 5 and 6 and converted into a parallel light beam by the collimator lens 7, and further 1/4 The light passes through the λ plate 8 and reaches the objective lens 9. The light collected by the objective lens 9 is It is irradiated onto the optical disk 10. The reflected light reflected by the optical disc 10 is again The beam splitter 6 passes through the objective lens 9, the 1/4 λ plate 8 and the collimating lens 7. Reflected by the toric lens 11 and given astigmatism by the toric lens 11, The light is received by the photodiode 12.

[0005]   On the other hand, when a DVD is set as the optical disc 10, a DVD laser is used. The light emitted from the diode 2 is diffracted by the diffraction grating 4 and divided into a plurality of light beams. Be done. The split light is reflected by the beam splitter 5 and is the same as in the case of the above-mentioned CD. The light is received by the photodiode 12 following the same path.

[0006]   In such an optical head device, when the diffraction grating is assembled to the frame, Adjusting the mounting position of the diffraction grating and temporarily fixing the diffraction grating to the frame It is necessary to adjust the rotation, and then fix it with an adhesive or the like. Diffraction grating The reason why the assembly has such a restriction is as follows.

[0007]   FIG. 8A is an external view of the diffraction grating. The diffraction grating 120 includes the first main surface 12 1a, a second main surface located on the opposite side of the first main surface 121a, and these main surfaces It is made of a transparent member having a substantially columnar shape, which is composed of a circumferential surface 123 that is continuously located on the surface. First The first main surface 121a and the second main surface 121b are provided with recesses. A diffraction grating surface 122 having a plurality of slits is formed on the bottom surface of the portion.

[0008]   The diffraction grating 120 disperses the light emitted from the light source into a plurality of light fluxes. Ie , The 0th order light (S1) and the ± 1st order diffracted light as shown in FIGS. 8 (b) and 8 (c). (S2, S3), ± 2nd order diffracted light ,. Here, the arrow shown in FIG. The position of the diffraction grating 120 in the mark D direction (the axial direction of the diffraction grating 120) is shown in FIG. It affects the distance d between the 0th order light (S1) and the ± 1st order diffracted lights (S2, S3) shown. Further, the diffraction grating in the direction of arrow E (direction around the axis of the diffraction grating 120) shown in FIG. The position of 120 is the 0th order light (S1) and the ± 1st order diffracted lights (S2, S2) shown in FIG. It affects the inclination angle α between the array axis in S3) and the information recording track 10a.

[0009]   For this reason, considering the accuracy of assembling the diffraction grating to the frame, after temporarily fixing It is essential to adjust the position of the diffraction grating. Therefore, the fixed structure of the diffraction grating For example, the structure disclosed in JP-A-8-306061 (Patent Document 1), etc. , Various structures have been proposed.

[0010]   The fixed structure of the diffraction grating disclosed in Patent Document 1 is a diffraction grating in which the diffraction grating is fitted. A structure in which multiple protrusions are formed on the outer circumference of the holder to make pressure contact with the holes provided in the frame Even after the diffraction grating is pressed into the hole of the frame, the diffraction grating holder is rotated around the axis. It is configured to be rotatable in any direction.

[0011]   In addition to the fixed structure of the diffraction grating disclosed in Patent Document 1, the following diffraction grating Fixed structures are known.

[0012]   FIG. 9 shows the shape of the diffraction grating used for the fixed structure of the diffraction grating in the first conventional example. It is an external view showing a shape. In addition, FIG. 10 shows the fixing of the diffraction grating in the first conventional example. FIG. 11 is a cross-sectional view showing the structure, and FIG. 11 is a cross-sectional view of the fixed structure of the diffraction grating shown in FIG. FIG. 12 is a cross-sectional view taken along line XI, and FIG. 12 is a cross-sectional view of the fixed structure of the diffraction grating shown in FIG. It is sectional drawing which follows the II-XII line. In addition, in FIG. 10 and FIG. Only the frame is shown in cross section for ease of solution.

[0013]   As shown in FIG. 9, the diffraction grating 220 in the first conventional example has the first main surface 22. 1a, a second main surface 221b (see FIG. 10) and a substantially cylindrical shape having a circumferential surface 223 It consists of a transparent member. In addition, the diffraction grating 220 has a circumferential surface 223 located at the lower end. Has a position adjusting groove 225.

[0014]   As shown in FIGS. 10 to 12, the frame 230 has an optical path extending in one direction. Is formed, and the diffraction grating 220 is fitted in the middle thereof. Diffraction grating 2 The inner diameter of the optical path of the portion in which 20 is fitted is slightly larger than the diameter of the diffraction grating 220. Well formed. That is, the circumferential surface 223 of the diffraction grating 220 and the frame 23 By contacting the inner wall surface 232 of 0, the diffraction grating 220 is attached to the frame 230. It is fixed. In addition, one of the light beams adjacent to the portion where the diffraction grating 220 is fitted is The inner diameter of the passage is formed smaller than the diameter of the diffraction grating 220. Because of this, the light The second main surface of the diffraction grating 220 is formed on the step surface 233 formed by reducing the diameter of the path. The abutment of 221b allows the diffraction grating 220 to be positioned in the axial direction. It

[0015]   On the other hand, the positioning of the diffraction grating 220 in the direction around the axis is performed using an eccentric pin. It Specifically, as shown in FIGS. 11 and 12, the shape is formed on the bottom surface of the frame 230. Insert an eccentric pin with an eccentric tip into the circular hole 234 formed, and attach this eccentric pin. By rotating the tip of the eccentric pin, the position adjusting groove 225 of the diffraction grating 220 is moved. And the diffraction grating 220 is rotated around the axis. This allows The position of the diffraction grating 220 in the direction around the axis is adjusted.

[0016]   FIG. 13 is a cross-sectional view showing a fixed structure of the diffraction grating in the second conventional example. Further, FIG. 14 is a sectional view taken along line XIV-XIV of the fixed structure of the diffraction grating shown in FIG. FIG. 15 is a plan view, and FIG. 15 is taken along line XV-XV of the fixed structure of the diffraction grating shown in FIG. 13. FIG. 13 and 14, in order to facilitate understanding, Only the frame is shown as a cross section.

[0017]   As shown in FIGS. 13 to 15, this conventional example also has the same structure as the first conventional example described above. The diffraction grating 320 having substantially the same shape as the diffraction grating 220 in FIG. Diffraction case The child 320 has a first main surface 321a, a second main surface 321b and a circumferential surface 323. It is composed of a substantially cylindrical transparent member. The diffraction grating 320 is located at the lower end. The circumferential surface 323 has a position adjusting groove 325.

[0018]   An optical path extending in one direction is formed in the frame 330, and the diffraction path is formed on the way. A grid 320 is located. The frame 330 has a circumferential surface 323 of the diffraction grating 320. A bottom surface 331a that comes into contact with the side surface 331b that comes into contact with another portion of the circumferential surface 323. , A total of three step surfaces 333 that come into contact with the second main surface 321b of the diffraction grating 320 And the diffraction grating 320 comes into contact with these three mounting surfaces. With, the diffraction grating 320 is positioned and arranged in the axial direction.

[0019]   A leaf spring 340 is attached to the frame 330 with screws 350, The leaf spring 340 is in contact with the circumferential surface of the diffraction grating 320. With this leaf spring 340 Therefore, the diffraction grating 320 is pressed and urged toward the frame 330. Based on the above Accordingly, the diffraction grating 320 is fixed to the frame 330.

[0020]   On the other hand, the positioning of the diffraction grating 320 in the direction around the axis is the same as in the above-described first conventional example. , Using an eccentric pin. Specifically, as shown in FIG. 14 and FIG. In addition, an eccentric pin whose eccentric tip is eccentric to a circular hole 334 formed on the bottom surface of the frame 330. Plug in and rotate this eccentric pin to diffract the tip of the eccentric pin. When the diffraction grating 320 is in contact with the wall surface that constitutes the position adjusting groove 325 of the child 320, Rotate around. This adjusts the position of the diffraction grating 320 in the direction around the axis. It

[0021]   In both the above-mentioned first and second conventional examples, the position adjustment of the diffraction grating is performed. After the knot, the adhesive is poured into the gap between the diffraction grating and the frame, and the The grid is fixed.

[0022]   Also, as an optical system other than the diffraction grating assembled in the optical pickup device, For example, there are collimating lenses and multi-lenses. Collimating lens is incident The multi-lens is a photodiode. It is an optical system that contributes to the focus control of the light radiated to the. Smell of these optical systems However, various fixing structures have been proposed.

[0023]   For example, as a fixing structure of a collimator lens, Japanese Patent Laid-Open No. 10-334472 There is a fixing structure disclosed in the publication (Patent Document 2). However, collimating lens In the fixed structure of, the position adjustment in the optical axis direction and the position adjustment in the plane perpendicular to the optical axis The nodes are important and the position adjustment in the axial direction necessary for the fixed structure of the diffraction grating is not possible. It is important. Therefore, the fixed structure of the collimator lens and the fixed structure of the diffraction grating However, there is a big difference in the fixed structure required.

[0024]   Further, as a fixing structure of a multi-lens, Japanese Patent Application Laid-Open No. 7-56076 (Patent There is a fixed structure disclosed in Reference 3). In the fixed structure of the multi-lens, the diffraction As with the fixed structure of the child, axial position adjustment and axial position adjustment become important. . However, the axial adjustment of the multi-lens itself is The photo detector can be replaced by adjusting the photo detector in the axial direction. Only orientation adjustment is important. Therefore, the fixed structure of the multi-lens and the diffraction There is a large difference in the required fixing structure from the child fixing structure.

[0025]

[Patent Document 1]   JP-A-8-306061

[0026]

[Patent Document 2]   JP, 10-334472, A

[0027]

[Patent Document 3]   JP-A-7-56076

[0028]

[Problems to be solved by the device]

  In the fixed structure of the diffraction grating disclosed in Patent Document 1, the leaf spring is unnecessary. A structure in which the diffraction grating is pressed into the frame is adopted for the purpose. However, pressure In order to keep the diffraction grating rotatable even after entering the Strict dimensional accuracy is required between the outer diameter of the dar and high processing accuracy. Therefore, there is a problem that the manufacturing cost increases.

[0029]   In the first conventional example described above, the diffraction grating covers the entire surface of the circumferential surface of the frame. Fixed and axially positioned by the stepped surface of the frame The structure is adopted. And the positioning around the axis should be in the direction of the bottom of the frame. The structure is adjusted by inserting an eccentric pin.

[0030]   Therefore, strict dimensional accuracy is required between the frame and the diffraction grating. Therefore, high processing accuracy was required. If the inner diameter of the frame is designed to be larger When the diffraction grating and the frame are bonded together, the Misalignment of the folded grid may occur, and the volume of adhesive remains There is a risk of axis deviation due to fluctuations, and this is not a preferable measure.

[0031]   Furthermore, a position adjusting groove provided at the lower end of the diffraction grating is provided on the bottom surface of the frame. It is very difficult to insert the diffraction grating into the frame so that it faces the cut hole. Yes, the work was complicated.

[0032]   In the second conventional example, the diffraction grating is formed on the bottom surface, side surface and step surface of the frame. It has a fixed structure that is fixed on the three surfaces of the Has been. Then, the axial positioning is performed by the step surface, and Positioning is done by inserting an eccentric pin from the bottom of the frame and adjusting the structure. ing.

[0033]   Therefore, three faces are required to fix the diffraction grating, which complicates the frame structure. There was a problem to do. Further, similarly to the above-mentioned first conventional example, the lower end portion of the diffraction grating is Rotate so that the position adjustment groove on the bottom faces the circular hole on the bottom of the frame. It was very difficult to insert the folding grid into the frame, and the work was complicated.

[0034]   As described above, in each of the above-mentioned conventional examples, the fixing structure is complicated and There has been a problem that the work of shaving is complicated. The size of the diffraction grating is The size of the diffraction grating is dramatically increasing, and the diameter of the diffraction grating is currently about several mm. It is becoming smaller. For this reason, the complicated fixing structure reduces the efficiency of assembly work. Was caused, and was a cause of putting pressure on the manufacturing cost.

[0035]   Therefore, the present invention has been made to solve the above problems. A fixed structure for a diffraction grating that facilitates positioning accuracy and an optical head equipped with this structure. The purpose is to provide a device.

[0036]

[Means for Solving the Problems]

  An optical head device according to a first aspect of the present invention includes a light source, a diffraction grating, and a frame. And a leaf spring. The diffraction grating divides the light emitted from the light source into multiple light beams. To divide. A diffraction grating is attached to the frame. Leaf springs Presses and urges the room. The diffraction grating should intersect the optical axis of the light emitted from the light source. A first and a second main surface located at, and a circumferential surface continuous with the first and the second main surface , A substantially columnar member having a D-cut portion extending on the circumferential surface in a direction intersecting the optical axis Consists of. The frames are arranged so that they intersect each other and abut on the circumferential surface of the diffraction grating. And a second mounting surface. The leaf spring intersects the optical axis inside the D-cut part of the diffraction grating. The diffraction grating by inserting it in the direction of It is pressed and urged toward the first and second mounting surfaces.

[0037]   In this way, the optical head device extends on the circumferential surface of the diffraction grating in the direction intersecting the optical axis. By providing the D-cut portion and arranging the leaf spring so as to pass through the D-cut portion, By adjusting the width of the leaf spring and the width of the D-cut portion, Positioning becomes easy. Therefore, the manufacturing of the optical head device is facilitated. The effect is obtained. As a result, it is possible to provide a high-performance optical head device at low cost. It will be possible.

[0038]   The fixing structure of the optical head device according to the present invention allows the light emitted from the light source to be emitted from a plurality of light sources. Fixing structure of the diffraction grating that fixes the diffraction grating divided into a bundle to the frame by using a pressing member It is a construction. The diffraction grating is located so as to intersect the optical axis of the light emitted from the light source. First and second main surfaces, a circumferential surface continuous with the first and second main surfaces, and on the circumferential surface In a substantially cylindrical member having a cut portion extending in a direction intersecting the optical axis. It The frame includes first and first frames that intersect each other and abut the circumferential surface of the diffraction grating. It has two mounting surfaces. The pressing member intersects the optical axis within the cut portion of the diffraction grating. The first direction by inserting it in the direction of And urged toward the second mounting surface.

[0039]   In this way, cut parts extending in the direction intersecting the optical axis are provided on the circumferential surface of the diffraction grating. By arranging the pressing member so as to pass through this cut portion, the width of the pressing member Adjusting the width between the cut part and the cut part facilitates axial positioning of the diffraction grating. You will be able to do it. For this reason, mounting the frame that abuts and fixes the diffraction grating It becomes possible to configure the surface with only two surfaces. As a result, the frame structure is simplified However, the assembly work becomes easy. Also, place this cut on the upper end of the diffraction grating. This allows the diffraction grating to be aligned around the axis when it is assembled to the frame. It is easy to check whether or not it is assembled to the frame at a certain angle. Therefore, the assembling work is further facilitated.

[0040]   In the structure for fixing the diffraction grating according to the present invention, for example, the cut portion is Is preferably a D-cut portion having a shape obtained by flatly cutting a part of the circumference of the diffraction grating. Good Thus, if the cut portion is the D cut portion, the diffraction grating can be easily formed. Naru

[0041]   In the structure for fixing the diffraction grating according to the present invention, for example, the pressing member is a plate. It is preferably a spring. As described above, if the pressing member is a leaf spring, a simple structure is obtained. The fixed structure will be realized by the formation.

[0042]   In the fixed structure of the diffraction grating according to the present invention, for example, the diffraction grating Preferably has a position adjusting groove for rotating the diffraction grating along the central axis. Good In this way, by providing the position adjusting groove on the upper end of the diffraction grating, Easy to adjust the position of the diffraction grating around the axis by inserting the Will be possible.

[0043]   An optical head device according to a second aspect of the present invention is a solid-state optical device including any one of the diffraction gratings described above. It has a fixed structure. With this configuration, the manufacturing of the optical head device is easy. It becomes possible to easily provide a high-performance optical head device at low cost.

[0044]

[Embodiment of device]

  An embodiment of the present invention will be described below with reference to the drawings.

[0045]   FIG. 1 shows a diffraction structure used in a fixed structure of a diffraction grating according to an embodiment of the present invention. It is an external view which shows the shape of a lattice. FIG. 2 shows the frame of the diffraction grating in the present embodiment. It is an exploded perspective view showing an assembly structure to a dome. Further, FIG. 3 shows the present embodiment. FIG. 4 is a cross-sectional view showing a fixed structure of the diffraction grating shown in FIG. FIG. 4 is a sectional view of the fixed structure taken along line IV-IV, and FIG. It is sectional drawing which follows the VV line of a constant structure. In addition, in FIG. 3 and FIG. In order to facilitate the above, only the frame is shown as a cross section.

[0046]   (Shape of diffraction grating)   First, the shape of the diffraction grating in the present embodiment will be described with reference to FIG. It As shown in FIG. 1, the diffraction grating 20 in the present embodiment emits light from a light source. The first main surface 21a and the second main surface 21 located so as to intersect the optical axis of the reflected light. b (see FIG. 3) and a circle continuous with the first main surface 21a and the second main surface 21b. It is made of a transparent member having a peripheral surface 23. Examples of the material include translucent resin and glass. Is used. The diffraction grating 20 has a first main surface 21a and a second main surface 21b. It has a diffraction grating surface 22. A plurality of slits are formed on the diffraction grating surface 22. The light is dispersed by the action of this slit.

[0047]   A D-cut portion 24, which is a cut portion, is located above the circumferential surface 23 of the diffraction grating 20. is doing. The D cut portion 24 extends in a direction intersecting the optical axis. Times like this By forming the D-cut portion 24 on the circumferential portion of the folded grid 20, Rims 26a and 26b are formed on the circumferential portion in the direction intersecting the optical axis. rim Of the 26a and 26b, the rim 26a located on the first major surface 21a side has a position adjustment A knot groove 25 is formed. That is, the position adjusting groove 25 is provided in the diffraction grating 20. It is located on the first main surface 21a side of the upper end portion.

[0048]   The D-cut has a D-shaped outline in a cross section in a direction intersecting the axis. It means to cut off the circumferential surface into a flat shape. However, in the present invention The D-cut portion is a cut portion formed by actually performing the D-cut processing. Not only include the part of the same shape as the shape obtained by this D-cut processing. I shall. That is, the diffraction grating of a cylindrical shape made of resin material or glass material The D-cut portion may be formed by actually D-cutting the circumferential surface, Injection molding using a resin material as the raw material so that the D-cut portion is integrally formed with other portions. The diffraction grating may be formed in a shape.

[0049]   (Assembly structure)   Next, the structure for assembling the diffraction grating in the present embodiment will be described. In Figure 2 As shown, a plate spring 40, which is a pressing member, is fixed at a predetermined position of the frame 30. A screw hole 36 to be screwed into the screw 50 for forming is formed. Near this screw hole 36 Beside it, there is a position to prevent the rotation of the leaf spring 40 while positioning the leaf spring 40. The positioning pin 38 is formed so as to project. The leaf spring 40 is provided on the frame Corresponding to the screw hole 36 and a screw fixing hole corresponding to the positioning pin 38. It has a hole 44 in its position.

[0050]   The diffraction grating 20 is pressed and urged to be fixed to the frame 30 via a leaf spring 40. It In the fixing structure of the diffraction grating 20 according to the present embodiment, the leaf spring 40 has two It has two pressure urging parts and has a structure to fix two diffraction gratings at the same time. It These two diffraction gratings are the diffraction grating 3 and the DV for the CD shown in FIG. 7, respectively. And the diffraction grating 4 for D. These two diffraction gratings have their axes in the horizontal direction. It is arranged so that it intersects substantially vertically.

[0051]   (Fixed structure of diffraction grating)   Next, with reference to FIGS. 3 to 5, the diffraction grating fixing structure according to the present embodiment. Will be described in detail. In addition, in FIG. 2, two diffraction gratings are connected to one plate Although a fixing structure for fixing with a screw is shown, understanding is made in FIGS. 3 to 5. For ease of explanation, explain the structure that fixes one diffraction grating with one leaf spring. To do.

[0052]   An optical path extending in one direction is formed in the frame 30, and diffraction is performed in the middle thereof. A grid 20 is located. The frame 30 contacts the circumferential surface 23 of the diffraction grating 20. A bottom surface 31a which is a first mounting surface and another portion of the circumferential surface 23 of the diffraction grating 20. It has a side surface 31b that is a second mounting surface that abuts. With these bottom surfaces 31a As shown in FIG. 4, the side surface 31b is the circumferential surface 23 of the diffraction grating 20 and the point A, respectively. And contact at point B.

[0053]   A leaf spring 40, which is a pressing member, is attached to the frame 30 with screws 50. Therefore, the leaf spring 40 moves inside the D-cut portion 24 provided at the upper end of the diffraction grating 20. It is arranged to be inserted. Bend downward at the tip of the leaf spring 40. The tongue 42 formed by being peeled off is located, and this tongue 42 is a circle of the diffraction grating 20. It is in contact with the peripheral surface 23. As shown in FIG. 4, this tongue piece 42 is formed on the diffraction grating 20. It is in contact with the circumferential surface 23 at a point C. That is, the diffraction grating 20 is attached to the leaf spring 40. Therefore, it is pressed and biased toward the bottom surface 31a and the side surface 31b.

[0054]   The positioning of the diffraction grating 20 in the axial direction is performed by the rims 26a provided on the diffraction grating 20, 26b and the leaf spring 40. As described above, the leaf spring 40 is the diffraction grating. It is inserted through the inside of the D-cut portion 24 provided in 20. Here, the width of the leaf spring 40 and Adjust the width of the D-cut portion 24 so that the leaf spring 40 and the rims 26a and 26b come into contact with each other. With this structure, the diffraction grating 20 can be positioned in the axial direction. Concrete Specifically, the width of the leaf spring 40 is made slightly smaller than the width of the D-cut portion 24. By fixing the leaf spring 40 so as to pass through the inside of the D-cut portion 24, The folding grid 20 can be positioned.

[0055]   On the other hand, positioning of the diffraction grating 20 in the direction around the axis is performed by using the rim 26a of the diffraction grating 20. This is performed by the position adjusting groove 25 provided. Specifically, the diffraction grating 20 By inserting the pin in a direction substantially parallel to the axial direction and moving the pin to the left and right The tip of the lever contacts the wall surface of the position adjusting groove 25, and the diffraction grating 20 moves in the axial direction. It comes to rotate. This allows the diffraction grating 20 to be positioned in the direction around the axis. Be seen.

[0056]   In the above structure, the leaf spring 40 and the bottom surface of the D-cut portion 24 are in contact with each other. Not in. Therefore, even when the diffraction grating 20 is rotated around the axis using the pin, If it is within the predetermined range, the leaf spring 40 contacts the bottom surface of the D-cut portion 24 and the leaf spring 40 It does not ride on the rims 26a and 26b from inside the D-cut portion 24. For this reason , The leaf spring 40 rides on the rims 26a and 26b to diffract the diffraction pattern in the axial direction. The displacement of the child 20 does not occur.

[0057]   (Action / effect)   With the above configuration, the width of the leaf spring and the width of the D cut portion can be adjusted. As a result, the diffraction grating can be positioned in the axial direction. For this reason, the diffraction grating The number of attachment surfaces of the frame that abuts against and is fixed to two surfaces has been reduced from the previously required three To do. As a result, the degree of freedom in designing the frame is increased and the frame structure is simplified. Thus, the work of assembling the diffraction grating can be facilitated. In addition, this D cut part By arranging it on the upper end of the diffraction grating, when assembling the diffraction grating to the frame, Check whether the diffraction grating is assembled to the frame at the correct angle around the axis. It will be easier to recognize. This allows for easier assembly work. It Also, as in the past, the diffraction grating is fixed only by the frame, leaf spring, and screws. The number of parts does not increase and the manufacturing cost does not increase. Yes. Furthermore, it is possible to easily adjust the position of the diffraction grating in the direction around the axis, so Assembly work becomes easier.

[0058]   The structure for fixing the diffraction grating described above is only for the temporary fixing stage. After that, the diffraction grating is actually attached to the frame with an adhesive or the like. It is necessary to fix the diffraction grating to the frame so that it cannot move relative to each other.

[0059]   In the above-described embodiment, the cut portion provided on the upper surface of the diffraction grating is D-shaped. Although the description has been given by exemplifying the case where the contact portion is used, it is not particularly limited to this. Yes. For example, it may be a recess or the like, and a cap through which the pressing member can be inserted. Any shape may be used as long as it is a toe portion.

[0060]   Further, in the above-described embodiment, the case where the diffraction grating made of one member is used Although explained using an example, it is called a diffraction grating holder or diffraction collar. Fix the auxiliary member to be mounted on the frame after fitting it to the outer periphery of the diffraction grating in the shape of a cylinder. The present invention is naturally applicable to the case where the structure is adopted. In this case, Toe parts and position adjusting grooves will be formed on the holder or collar.

[0061]   Further, the present invention is a CD, a CD-ROM (Compact Disc-Read Only Memory), CD-R (Compact Disc-Recordable), CD-RW (Compact Disc-Rewritable) ), DVD, DVD-ROM (Digital Versatile Disc-Read Only Memory), All types of optical information such as DVD-RW (Digital Versatile Disc-Rewritable) It is applicable to an optical head device for recording media.

[0062]   As described above, the above-described embodiments disclosed this time are examples in all respects, and It's not the one. The technical scope of the present invention is defined by the scope of claims for utility model registration. And the meaning equivalent to the scope of claims for utility model registration and all within the scope It includes the change of.

[0063]

[Effect of device]

  As described above, the fixed structure of the diffraction grating according to the present invention is adopted. As a result, high positioning accuracy can be easily realized. Because of this, It is possible to provide a functional optical head device at low cost.

[Brief description of drawings]

FIG. 1 is an external view showing a shape of a diffraction grating used in a structure for fixing a diffraction grating according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a structure for assembling the diffraction grating to the frame according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a structure for fixing a diffraction grating according to the embodiment of the present invention.

4 is a IV-IV of the fixed structure of the diffraction grating shown in FIG.
It is sectional drawing which follows the line.

5 is a sectional view taken along line VI of the fixed structure of the diffraction grating shown in FIG.

FIG. 6 is a schematic diagram for explaining a three-beam method.

FIG. 7 is a schematic diagram showing a configuration of a two-light source type optical head device having light sources corresponding to a CD and a DVD respectively.

FIG. 8A is an external view of a diffraction grating, and FIG.
6C and 6C are schematic diagrams showing how the dispersed light is applied to the optical disc.

FIG. 9 is an external view showing the shape of a diffraction grating used in the fixed structure of the diffraction grating in the first conventional example.

FIG. 10 is a cross-sectional view showing a fixed structure of a diffraction grating in a first conventional example.

11 is a cross-sectional view of the fixed structure of the diffraction grating shown in FIG.
It is sectional drawing which follows the XI line.

12 is an XII of the fixed structure of the diffraction grating shown in FIG.
It is sectional drawing which follows the -XII line.

FIG. 13 is a cross-sectional view showing a fixed structure of a diffraction grating in a second conventional example.

14 is an XIV of the fixed structure of the diffraction grating shown in FIG.
It is sectional drawing which follows the -XIV line.

FIG. 15 is an XV- of the fixed structure of the diffraction grating shown in FIG.
It is sectional drawing which follows the XV line.

[Explanation of symbols]

1 laser diode for CD, 2 laser diode for DVD, 3, 4 diffraction grating, 5, 6 beam splitter, 7 collimating lens, 8 1/4 λ plate, 9 objective lens, 10 optical disk, 10a information recording track,
10b guide track, 10c pit, 11 toric lens, 12 photodiode, 20 diffraction grating, 21a first main surface, 21b second main surface, 22
Diffraction grating surface, 23 Circumferential surface, 24 D cut part, 25
Position adjustment groove, 26a, 26b rim, 30 frame,
31a Bottom surface, 31b Side surface, 36 Screw hole, 38 Positioning pin, 40 Leaf spring, 42 Tongue piece, 44 hole, 5
0 screw.

Claims (6)

[Scope of utility model registration request] 1. A light source, a diffraction grating that divides the light emitted from the light source into a plurality of light beams, a frame in which the diffraction grating is assembled, and a leaf spring that presses and biases the diffraction grating against the frame. Wherein the diffraction grating has first and second main surfaces positioned so as to intersect the optical axis of light emitted from the light source, and a circumferential surface continuous with the first and second main surfaces. And a substantially cylindrical member having a D-cut portion extending on the circumferential surface in a direction intersecting the optical axis, the frames intersect each other, and contact the circumferential surface of the diffraction grating. Having first and second attachment surfaces in contact with each other, the leaf spring is inserted through the inside of the D-cut portion of the diffraction grating in a direction intersecting the optical axis, and is in contact with the circumferential surface of the diffraction grating. To attach the diffraction grating to the first and second mounting surfaces. An optical head device that presses and urges toward the optical head device. 2. A fixed structure of a diffraction grating for fixing a diffraction grating for dividing light emitted from a light source into a plurality of light beams to a frame by using a pressing member, wherein the diffraction grating is a light emitted from the light source. The first and second main surfaces that are located so as to intersect the optical axis of, the circumferential surface that is continuous with the first and second main surfaces, and the direction that intersects the optical axis on the circumferential surface. The frame includes a substantially cylindrical member having an extended cut portion, the frame has first and second mounting surfaces that intersect each other and contact the circumferential surface of the diffraction grating, and the pressing member. Is inserted through the cut portion of the diffraction grating in a direction intersecting the optical axis and abuts on the circumferential surface of the diffraction grating so that the diffraction grating faces the first and second mounting surfaces. The fixed structure of the diffraction grating, which is urged by pressing. 3. The fixed structure of the diffraction grating according to claim 2, wherein the cut portion is a D cut portion having a shape in which a part of the circumference of the diffraction grating is cut in a plane. 4. The diffraction grating fixing structure according to claim 2, wherein the pressing member is a leaf spring. 5. The fixing structure for a diffraction grating according to claim 2, wherein the diffraction grating has a position adjusting groove for rotating the diffraction grating along a central axis. 6. An optical head device comprising the structure for fixing a diffraction grating according to claim 2.