JP2007328846A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device which is made to improve recording/reproduction performance by raising press fitting accuracy of a laser diode by making an aperture of a holder through which laser diode is press fitted can be easily formed with sufficient accuracy to reduce defective occurrence rate in an assembly process. <P>SOLUTION: In an optical pickup device in which the laser diode 2 is press fitted and fixed to an aperture 3a of a holder 3, and the holder 3 is set on a base chassis 1, an annular concave groove section 3e is provided as a thinned section so that annular wall section 3d may be formed in perimeter of an aperture 3a of the holder 3. Thermal contraction of the annular wall section 3d immediately after molding of holder is decreased by the annular concave groove section 3e as the thinned section so that the aperture 3a can be simply formed with sufficient accuracy so that contained aperture diameter and aperture location and size may fall within range of tolerance, thereby enhancing the press fitting accuracy for the laser diode 2. Thus, enhancement in recording/reproduction performance and lowering of defect occurrence rate can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup device mounted on an optical disk recording / reproducing apparatus such as a DVD player / recorder, and in particular, a laser diode press-fitting accuracy by making it possible to more easily and accurately mold a hole of a holder for press-fitting a laser diode. It is related with the optical pick-up apparatus which aimed at the improvement of recording / reproducing performance, and the reduction of the defective product generation rate in an assembly process by improving this.

  An optical pickup device mounted on an optical disk recording / reproducing device is a laser diode in which a laser diode, a grating, a beam splitter, a rising mirror (prism mirror), an objective lens, a photodetector, etc. are attached to a base chassis. The laser beam emitted from the beam is diffracted into three beams by the grating, and the beam that has passed through the beam splitter is reflected upward by the rising mirror and focused on the objective lens while being focused on the recording surface of the optical disk. Is detected and detected by a photodetector.

  In such an optical pickup device, a laser diode is press-fitted and fixed in a hole in a zinc die-cast holder using a hand press on the production line, and the laser diode is installed in front of the grating by attaching this holder to the base chassis. However, since the tilt of the optical axis of the laser beam emitted from the laser diode greatly affects the recording / reproducing performance, there are strict tolerances on the positional accuracy and perpendicularity of the holder hole into which the laser diode is pressed. Dimensions are needed.

  However, the laser diode holder has a thick wall around the hole into which the laser diode is press-fitted and has a large thermal shrinkage (so-called retreat) immediately after molding, so that the hole diameter and hole position dimensions can be kept within the tolerance range. There is a problem that it is not easy to put out accurately.

On the other hand, a thick screw tightening part is formed at two opposite positions of the laser diode holder, and a thin part thinner than both screw tightening parts is formed in the middle of both screw tightening parts. There has been proposed a laser diode holder for an optical pickup in which a thin-walled concave portion for fitting is formed (Patent Document 1).
Japanese Utility Model Publication No. 63-87634

  The laser diode holder for optical pickup disclosed in Patent Document 1 can be appropriately screwed and fixed by bringing two thick screw tightening portions into close contact with an opt-base (base chassis). Since the periphery of the thin-walled recess that fits the inner wall is not thinned, the heat shrinkage immediately after molding is large, and the hole diameter and hole position dimensions are within the tolerance range. There is a problem that it is not easy to put out with high accuracy, so that there is a possibility that the recording / reproducing performance is lowered and the generation rate of defective products is increased in the assembly process.

  The present invention has been made under the circumstances described above, and it is possible to easily and accurately mold the hole of the holder for press-fitting the laser diode, thereby improving the press-fitting accuracy of the laser diode, improving the recording / reproducing performance, and the assembly process. It is a problem to be solved to provide an optical pickup device in which the occurrence rate of defective products is reduced.

  In order to solve the above problems, an optical pickup device according to the present invention is an optical pickup device in which a laser diode is press-fitted and fixed in a hole of a holder, and the holder is attached to a base chassis. The meat stealing portion is provided so as to be formed.

  In the optical pickup device of the present invention, it is preferable that an annular groove portion is provided concentrically with the hole of the holder as the meat stealing portion.

  In a further preferred optical pickup device according to the present invention, a laser diode is press-fitted and fixed in a hole of a holder, and this holder is attached to a base chassis. The optical pickup device has a thickness of 1 around the hole of the holder. An annular groove portion is provided concentrically with the hole of the holder as a meat stealing portion so that an annular wall portion of ˜1.5 mm is formed.

  In the optical pickup device of the present invention, the meat stealing portion is provided so that the annular wall portion is formed around the hole of the holder for press-fitting the laser diode, so that the thermal contraction of the annular wall portion immediately after the holder molding is reduced. In addition, the influence of the heat shrinkage on the dimensional accuracy of the hole is reduced. Therefore, the hole of the holder into which the laser diode is press-fitted can be accurately formed so that the hole diameter and hole position size are within the tolerance range, so the press-fitting accuracy of the laser diode is increased and recording / reproduction performance is improved. At the same time, the defective product generation rate in the assembly process is reduced.

  In the case where the annular groove portion is provided concentrically with the hole of the holder as the meat stealing portion, the thickness of the annular wall portion is constant over the entire circumference, and the distortion of the annular wall portion due to thermal contraction is less likely to occur. Therefore, the dimensional accuracy of the hole of the holder is further improved. In particular, in the case where the annular groove portion is provided concentrically with the hole of the holder as a stealing portion so that an annular wall portion having a thickness of 1 to 1.5 mm is formed, the thickness of the annular wall portion is set to 1-1. By reducing the thickness to 5 mm, the thermal shrinkage of the annular wall portion is greatly reduced, so that the dimensional accuracy of the hole of the holder can be further improved.

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

  1 is a plan view of an optical pickup device according to an embodiment of the present invention, FIG. 2 is a bottom view of the optical pickup device, and FIG. 3 is a perspective view of a laser diode and its holder mounted on the optical pickup device. 4 is a sectional view of the holder before the laser diode is press-fitted, and FIG. 5 is an enlarged partial sectional view of the optical pickup device.

  This optical pickup device is mounted on an optical disk recording / reproducing device such as a DVD player / recorder. As shown in FIGS. 1, 2, and 5, one end of the base chassis 1 (on the left side in the figure). At the end, a holder 3 into which a laser diode 2 for irradiating a laser beam is press-fitted is attached.

  In front of the laser diode of the base chassis 1 (irradiation direction), a grating lens 4 that diffracts the laser beam to generate three beams, a beam splitter 5 that arbitrarily divides the beam into reflection and transmission, and divides the beam into two, A rising mirror 6 that reflects the transmitted beam upward is arranged and attached in series. An objective lens 7 that collects the beam and irradiates the optical disk is mounted on the rising mirror 6. Yes. A sensor lens 8 and a photodetector 9 are mounted on one side of the beam splitter 5.

  Further, bearing portions 10a and 10b are formed on both the left and right sides of the base chassis 1, and the optical pickup device serves as two guide shafts (a main shaft and a sub shaft) of the optical disk recording / reproducing device by the bearing portions 10a and 10b. It is designed to be slidably mounted on.

  The optical pickup device diffracts the laser beam emitted from the laser diode 2 into three beams by the grating lens 4 while sliding toward the rotary table of the optical disc along the two guide shafts of the optical disc recording / reproducing device. Recording / reproduction is performed by reflecting the beam transmitted through the beam splitter 5 toward the objective lens 7 with the rising mirror 6, condensing with the objective lens 7 and irradiating the optical disc.

  A major feature of this optical pickup device is a zinc die-cast holder 3 for press-fitting and fixing the laser diode 2. As shown in FIGS. 3 to 5, the holder 3 is formed with a hole 3 a into which the laser diode 2 is press-fitted in the center, and the hole 3 a is a disk-shaped base portion 2 a of the laser diode 2. The large-diameter hole portion 3b into which the laser diode 2 is press-fitted and the small-diameter hole portion 3c into which the main body portion 2b of the laser diode 2 is loosely fitted are different diameter holes.

  An annular groove 3e as a stealing portion is provided concentrically with the hole 3a so that an annular wall 3d is formed around the large-diameter hole 3b of the hole 3a. The annular groove 3e as the meat stealing portion reduces the heat shrinkage (so-called retreat) of the annular wall 3d immediately after the holder 3 is molded, and the large hole 3a for press-fitting the pedestal 2a of the laser diode 2 is large. It is formed to increase the dimensional accuracy of the diameter hole 3b, and the annular groove 3e is formed concentrically with the hole 3a so that the thickness of the annular wall 3d is constant over the entire circumference. Further, distortion is less likely to occur in the annular wall portion 3d due to heat shrinkage. The groove width of the annular groove 3e is not limited, but is suitably set within a range of 1 to 2 mm. In addition, the shape of the meat stealing portion may be any shape as long as the annular wall portion 3d is formed, and is not limited to the annular concave groove portion 3e.

  The thickness of the annular wall portion 3d is preferably set in the range of 1 to 1.5 mm, and when it is thinner than 1 mm, the base portion 2a of the laser diode 2 is pressed into the large-diameter hole portion 3b of the hole 3a. There is a risk that the annular wall 3d may be deformed or damaged. On the other hand, if it is thicker than 1.5 mm, the thermal shrinkage of the annular wall 3d immediately after molding increases, so the hole diameter of the large-diameter hole 3b and other related matters. It will not be easy to accurately place the dimensions within tight tolerances.

  In addition, the holder 3 is formed with two screw insertion holes 3f and two convex portions 3g that determine the mounting position of the heat sink.

  The laser diode 2 is press-fitted into the large-diameter hole 3b of the hole 3a of the holder 3 using a hand press, and the laser diode body 2b is loosely fitted into the small-diameter hole 3c of the hole 3a. Thus, the holder 3 is fixed to the hole 3a. The holder 3 to which the laser diode 2 is press-fitted and fixed is disposed on the side surface of the base chassis 1 so that the laser diode 2 and the grating lens 4 are opposed to each other as shown in FIG. The heat radiating plate 11 is positioned and overlapped by the convex portion 3g and attached to the side surface of the base chassis 1 with screws 12 screwed into the base chassis 1 from the heat radiating plate 11 through the screw insertion holes 3f of the holder 3.

  In the optical pickup device configured as described above, the holder 3 has an annular groove portion 3e as a stealing portion so that an annular wall portion 3d is formed around the large-diameter hole portion 3b of the hole 3a into which the laser diode 2 is press-fitted. Therefore, the thermal contraction of the annular wall 3d immediately after the holder molding is greatly reduced, and the influence of the thermal contraction on the dimensional accuracy of the hole 3a (especially the large diameter hole 3b) is reduced. Since it becomes easy to form the hole 3a of the holder 3 with high accuracy so that the hole position size falls within the tolerance range, the press-fitting accuracy of the laser diode 2 is increased, and the recording / reproducing performance is improved. The defective product occurrence rate in the assembling process is lowered, and the effect of facilitating production of a holder molding die can be obtained.

1 is a plan view of an optical pickup device according to an embodiment of the present invention. It is a bottom view of the optical pickup device. It is a perspective view of the laser diode and its holder mounted in the optical pickup device. It is sectional drawing of the holder before press-fitting a laser diode. It is an expanded partial sectional view of the optical pickup device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base chassis 2 Laser diode 2a Laser diode base part 3 Holder 3a Hole 3b Large diameter hole part 3c Small diameter hole part 3d Annular wall part 3e Annular groove part

Claims (3)

In the optical pickup device in which the laser diode is press-fitted and fixed in the hole of the holder, and this holder is attached to the base chassis,
An optical pickup device characterized in that an annular groove portion is provided concentrically with the hole of the holder as a stealing portion so that an annular wall portion having a thickness of 1 to 1.5 mm is formed around the hole of the holder. . In the optical pickup device in which the laser diode is press-fitted and fixed in the hole of the holder, and this holder is attached to the base chassis,
An optical pickup device, wherein a meat stealing portion is provided so that an annular wall portion is formed around the hole of the holder.   3. The optical pickup device according to claim 2, wherein an annular groove portion is provided concentrically with the hole of the holder as the meat stealing portion.

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