JP2010055654A - Optical pickup and objective lens assembly of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical pickup and an objective lens assembly which reduce areas of circuit boards and increase the number of lands for soldering the ends of coils and suspension wires. <P>SOLUTION: The objective lens assembly includes: a lens holder 20 holding objective lenses 21 and 22; focusing coils 23 and a tracking coil 24; and circuit boards 30 fixed to the end faces of the lens holder 20. The circuit board 30 comprise the suspension wires 3 for supporting the lens holder 20 movably in parallel to a supporter 1 and the lands for soldering the ends of the coils. The circuit boards 30 are fixed to both end faces of the lens holder 20, have the same shapes as those of the respective end faces, and have circuit patterns on both front and rear surfaces. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical pickup and an objective lens assembly thereof, and in particular, has a feature in the configuration of a movable body that holds an objective lens and a circuit board that is fixed to the movable body and fixes a coil terminal and a suspension wire. It is.

  The optical pickup is used as a signal conversion element of a recording / reproducing apparatus using an optical disc such as a CD (compact disc) or a DVD (digital versatile disc) as a recording medium. The optical pickup is roughly composed of an objective lens assembly and a support, and the objective lens assembly is supported by a suspension wire extending from the support. The objective lens assembly includes an objective lens, a lens holder that holds the objective lens, and a focusing coil and a tracking coil fixed to the lens holder as main components. A focusing magnet and a tracking magnet are fixed to the support so as to face the coils. A plurality of the suspension wires are arranged in parallel to support the objective lens assembly in a cantilever manner with respect to the support, and the objective lens assembly is translated in the optical axis direction by a thrust generated between the focusing coil and the focusing magnet. And the parallel movement of the objective lens assembly in the tracking direction is allowed by the thrust generated between the tracking coil and the tracking magnet.

  In a conventional general optical pickup, a circuit board is fixed to a lens holder, and one end portions of the plurality of suspension wires are soldered to a predetermined soldering land on the circuit board, and terminals of the coils are fixed to a predetermined solder. Each coil is electrically connected to a focusing control circuit, a tracking control circuit, etc. via a suspension wire.

  In recent optical pickups, the number of coils increases and the number of coil terminals to be wired tends to increase in order to accurately drive the objective lens assembly and perform focusing control and tracking control with high accuracy. In recent years, for example, it is required that tilt control of the objective lens assembly is possible, and there are many examples in which three suspension wires are arranged on both sides of the objective lens assembly, for a total of six. Yes. Under such circumstances, the number of soldered portions on the circuit board tends to be very large.

  On the other hand, high-performance optical pickups are being reduced in size in order to improve sensitivity characteristics or response characteristics, and accordingly, the area of the circuit board is also reduced. Therefore, on the one hand, the number of soldering points on the circuit board has increased, and on the other hand, the area of the circuit board has decreased, making it very difficult to configure the circuit pattern formed on the circuit board. In particular, for example, in the optical pickup provided with a plurality of objective lenses so as to be compatible with both a conventional DVD recording medium and a next-generation recording medium such as Blu-ray, the above-mentioned problem has become prominent.

  As a prior art that may contribute to solving the problems in the optical pickup as described above, a notch that allows laser light to pass is provided in a part of the side wall of the objective lens holder, and laser light is incident on a pair of focusing coils. The pair of focusing coils can be placed in a diagonal position with the center of gravity of the movable part as a center so that the focusing coil on the side to be moved can be shifted toward the tracking coil. There is known an objective lens actuator that can be made thin by disposing a mirror immediately below the objective lens (see, for example, Patent Document 1).

In addition, the focusing coil and tracking coil lead wires assembled in the lens holder are aligned with the guide groove provided in the lens holder, and the relay board is attached to the lens holder so that the lead terminal is on the suspension holder side. An optical pickup is known in which the lead wire of the coil is soldered to a lead terminal of a substrate so that the entire objective lens driving unit can be reduced in size and thickness (see Patent Document 2).
A relay substrate is provided on the lens holder, and the lens holder is formed with a pair of L-shaped projecting portions having a surface parallel to and perpendicular to the coil terminal wiring surface of the relay substrate, and connecting between the projecting portions. An optical pickup that can improve soldering workability during wiring processing by arranging a land for soldering a coil terminal on a wire is also known (see Patent Document 3).

JP 2007-234112 A JP-A-10-188307 JP-A-8-115527

  As described above, while the area of the circuit board fixed to the lens holder is reduced, an increase in the number of coils secures more lands for soldering the coil terminals and lands for soldering the suspension wires. Since it is necessary, some ideas are required for the configuration of the circuit board. However, according to the conventional optical pickup including the prior art described in each of the above patent documents, it is possible to reduce the area of the circuit board and increase the number of lands for soldering the coil terminal and the suspension wire. Ingenuity is not enough.

The present invention has been made in view of the circumstances of the prior art as described above, and is an optical pickup capable of achieving both a reduction in the area of a circuit board and an increase in the number of lands for soldering coil ends and suspension wires. And an objective lens assembly thereof.
In the present invention, in order to further promote downsizing, the cross-sectional shape of the lens holder is irregular, and the circuit board corresponding to this is also an irregular circuit board, and even if the area is small, the coil terminal and An object of the present invention is to provide an optical pickup and an objective lens assembly thereof in which a suspension wire can be easily soldered.

The present invention includes an objective lens, a lens holder that holds the objective lens, a focusing coil and a tracking coil, and a circuit board fixed to an end face of the lens holder, and the circuit board supports the lens holder. An objective lens assembly having a suspension wire for supporting a body so as to be movable in parallel and a land for soldering a terminal of each coil, wherein the circuit board is provided at both end faces of the lens holder. The main features are that they are fixed to each other and have the same shape as the respective end surfaces, and that circuit patterns are formed on both front and back surfaces.
The optical pickup according to the present invention includes the objective lens assembly according to the present invention as an objective lens assembly constituting the optical pickup.

The circuit board fixed to both end faces of the lens holder has circuit patterns formed on both the front and back surfaces. Therefore, the number of coils arranged on the lens holder is increased, or the number of suspension wires is increased. Even if the number increases, a space for arranging these lands can be secured.
Even if the shape of the circuit board is different from the shape of the end surface of the lens holder, by forming a circuit pattern on both the front and back surfaces of the circuit board, a land for soldering the end of each coil and the suspension wire Can be secured.

Embodiments of an optical pickup and its objective lens assembly according to the present invention will be described below with reference to the drawings.
1 and 2 show an embodiment of an optical pickup according to the present invention. This optical pickup is roughly composed of a support 1, a portion of the objective lens assembly 2, and a suspension wire 3 that supports the objective lens assembly 2 so as to be movable with respect to the support 1.

  The support 1 is mainly composed of a yoke base 11 formed by punching and bending a plate made of a magnetic material, and a gel holder 12 is fixed to one side of the lower end portion in FIGS. A control circuit board 14 is fixed to the circuit board. The base end portion of the suspension wire 3 is disposed through each gel holder 12 and the control circuit board 14. Three suspension wires 3 pass through each gel holder 12, and the base end portion of each suspension wire 3 is soldered to a predetermined soldering land of the control circuit board 14, so that each suspension wire 3 is parallel to each other in the figure. It is fixed in a standing posture. The gel holder 12 is filled with a buffer material so that the suspension wire 3 does not vibrate unnecessarily by absorbing external vibration. A flexible circuit board 15 is pulled out from the control circuit board 14 and connected to an external circuit. In the figure, the objective lens optical axis is drawn in a horizontal orientation, but the objective lens optical axis may be used in a vertical orientation. In this case, the suspension wires 3 are parallel to each other. It will extend in the horizontal direction.

  The upper end portion of the yoke base 11 is bent in the horizontal direction, and the intermediate portion in the vertical direction of the yoke base 11 is bent in the horizontal direction by cutting and raising, and magnets 13 are fixed to the opposing surfaces of these bent portions. Yes. These magnets 13 oppose a focusing coil 23 and a tracking coil 24 disposed above and below an objective lens assembly 2 described later, respectively, at appropriate intervals. Further, these magnets 13 are magnetized in a predetermined pattern so as to generate a thrust in the focusing direction with the focusing coil 23 and generate a thrust in the tracking direction with the tracking coil 24.

  Next, the configuration of the objective lens assembly 2 will be described with reference to FIGS. 4 and 5 together. The objective lens assembly 2 has a lens holder 20 as a base, and has two objective lenses 21, 22, four focusing coils 23, two tracking coils 24, and two circuit boards 30 fixed to the lens holder 20. It becomes. The two objective lenses 21 and 22 are arranged in the left-right direction in the drawing at a predetermined interval so that a laser beam from a laser light source (not shown) is guided in parallel with the arrangement direction of the objective lenses 21 and 22. ing. In order to reduce the size and thickness of the objective lens assembly 2 and the optical pickup using the objective lens assembly 2, the laser beam is guided to a position close to the objective lenses 21 and 22, and the optical axis thereof is close to the objective lenses 21 and 22. The laser beam is reflected toward the objective lenses 21 and 22 by the prism disposed on the top. Therefore, the lens holder 20 has a U-shaped cross section in the entire length direction (diagonal left and right direction in FIGS. 4 and 5), and the prism is formed in a space surrounded by three sides constituting the U shape. Are arranged so that a laser beam is guided from the U-shaped end face toward the prism.

  Objective lenses 21 and 22 are disposed through a portion corresponding to the bottom surface of the U-shaped cross section of the lens holder 20. The laser light introduced into the lens holder 20 as described above is reflected toward the objective lenses 21 and 22 by the prism, and is condensed by the objective lenses 21 and 22 onto a recording surface of an optical disc (not shown). The reflected light from the recording surface returns in the order of the objective lenses 21 and 22 and the prism. Light transmitted through or reflected by the prism is detected by a photodetector (not shown), and data recorded on the optical disk is read out, and focusing detection and tracking detection are performed. An appropriate number of lens protection projections 25 protruding from the front end surfaces of the lens barrels of the objective lenses 21 and 22 are provided on the outer surfaces of the attachment portions of the objective lenses 21 and 22 of the lens holder 20, and external members are the objective lenses 21 and 22. Before contacting the lens 22, the lens protection projection 25 is contacted to protect the objective lenses 21 and 22.

  Two opposing coils of the lens holder 20 having a U-shaped cross section, that is, two outer coils on the upper and lower sides in the figure, are each sandwiched between two focusing coils 23 and one focusing coil. The tracking coil 24 is fixed. Therefore, there are a total of four focusing coils 23 and a total of two tracking coils 24. The arrangement direction of the coils 23 and 24 is substantially parallel to the arrangement direction of the objective lenses 21 and 22 in consideration of the weight balance of the entire objective lens assembly 2.

  As described above, the lens holder 20 has a U-shaped cross section, and both end surfaces are also U-shaped. The two circuit boards 30 are fixed to both end faces of the lens holder 20. The shape of the circuit board 30 is also U-shaped in accordance with the end face shape of the lens holder 20 so that the circuit board 30 does not block the introduced laser beam. Both of the two circuit boards 30 are for wiring processing of the ends of the coils 23 and 24 and for fixing the tip end portion of the suspension wire 3. The land 32 for soldering the coil ends and the suspension wire 3 are soldered. It has a land 31 for attaching. In order to accurately position the circuit board 30 with respect to the lens holder 20, a positioning projection 26 that makes the outer surface of the circuit board 30 abut on the end surface of the lens holder 20 and a notch formed at the upper end of the circuit board 20. Another positioning projection 27 is formed to engage the two.

  As described above, since the circuit board 30 has the same U-shape as the end face shape of the lens holder 20, the entire area is small, and it is spatially necessary to form a soldering land and a wiring pattern. There is no room for the spread. Therefore, the circuit board 30 is a double-sided board in which circuit patterns are formed on both sides. When the fixing surface of each circuit board 30 to the lens holder 20 is the back surface and the opposite surface is the front surface, the suspension wire 3 is soldered to the surface side of each circuit board 30 as shown in FIGS. A land 32 for soldering the land 31 to the coil terminal and a circuit pattern for connecting the lands as necessary are formed. On the back surface side of each circuit board 30, an intermediate pattern 33 that connects a predetermined circuit pattern on the front surface side through a through hole is formed.

  The objective lens assembly 2 is supported by the support 1 by soldering the tip of the suspension wire 3 to each land 31 of each circuit board 30. The suspension wire 3 has elasticity, and a total of six suspension wires 3 extend in parallel to support the objective lens assembly 2 in a cantilever manner. As a result, the objective lens assembly 2 can be translated in the optical axis direction of the objective lenses 21 and 22, that is, the focusing direction and the tracking direction that is orthogonal to the optical axis. The objective lens assembly 2 is positioned between the upper and lower magnets 13 while being supported by the suspension wire 3, and the upper and lower focusing coils 23 and the tracking coil 24 are spaced apart from the upper and lower magnets 13 by appropriate intervals. Opposite. Each coil 23, 24 is in the magnetic field formed by the magnet 13. Accordingly, when a control current is passed through the focusing coil 23, thrust in the focusing direction is generated, and the objective lens assembly 2 moves in the focusing direction. When a control current is passed through the tracking coil 24, a thrust in the tracking direction is generated and the objective lens assembly 2 moves in the tracking direction.

  Control currents to the coils 23 and 24 are supplied from an external control circuit via the suspension wire 3 and further via the soldering land 31, the circuit pattern, and the soldering land 32 of the circuit board 30. Here, the electrical connection of the coils 23 and 24 will be described with reference to FIG. 1 to 5, the focusing coil is indicated by reference numeral 23 and the tracking coil is indicated by reference numeral 24. In FIG. 6, the focusing coil is indicated by reference numerals 231, 232, 233, and 234, and the tracking coil is indicated by reference numerals 241 and 242. Is shown. 1 to 4, the reference numeral 231 indicates the upper left focusing coil, the reference numeral 232 indicates the upper right focusing coil, the reference numeral 241 indicates the upper tracking coil, the reference numeral 233 indicates the lower left, and the reference numeral 232 indicates the lower right focusing coil. Reference numeral 242 denotes a lower tracking coil.

  In the conventional general optical pickup, all the focusing coils are connected in series. In this embodiment, however, the left focusing coils 231 and 233 and the right focusing coils 232 and 234 are separately connected in series. Yes. The reason is that it is possible to control the tilt or tilt of the objective lens assembly 2 in the left-right direction by individually controlling the current supplied to the left and right focusing coils. The focusing control signal is simultaneously supplied to the left and right focusing coils.

  Thus, in recent optical pickups, tilt control can be performed in addition to focusing control and tracking control. Along with this, the circuit pattern of the circuit board 30 and the number of soldering lands of the objective lens assembly 2 that relays each coil and external circuit increase, and the number of suspension wires 3 increases to a total of six as in the illustrated embodiment. is there. While the configuration of the circuit board of the objective lens assembly tends to become complicated as the number of coils increases, the technically conflicting problem of reducing the area of the circuit board is an implementation of the present invention. In the example, the problem is solved by forming circuit patterns on both the front and back surfaces of the circuit board 30.

It is a disassembled perspective view which shows the Example of the optical pick-up concerning this invention in the state which isolate | separated the objective lens assembly from the support body. It is the perspective view which looked at the said Example from the lower side. It is the perspective view which looked at the said Example from the upper side. It is the disassembled perspective view which looked at the Example of the objective-lens assembly which concerns on this invention from the upper one direction. It is the disassembled perspective view which looked at the Example of the objective-lens assembly which concerns on this invention from the upper direction other direction. It is a circuit diagram which shows each coil connection relationship of the said Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Objective lens assembly 3 Suspension wire 11 Yoke base 12 Gel holder 13 Magnet 20 Lens holder 21 Objective lens 22 Objective lens 23 Focusing coil 24 Tracking coil 30 Circuit board

Claims (8)

An objective lens, a lens holder that holds the objective lens, a focusing coil and a tracking coil, and a circuit board fixed to an end face of the lens holder,
The circuit board is an objective lens assembly having a suspension wire for supporting the lens holder so as to be movable in parallel with a support and a land for soldering the terminal of each coil.
An objective lens assembly in which the circuit board is fixed to both end faces of the lens holder and has the same shape as each end face, and circuit patterns are formed on both front and back surfaces.   2. The objective lens assembly according to claim 1, wherein lands for soldering suspension wires and terminals of the respective coils are formed on the surface side of each circuit board.   3. The objective lens assembly according to claim 2, wherein an intermediate pattern for connecting the end of each coil and the suspension wire is formed on each circuit board.   The lens holder has a different cross-sectional shape in order to introduce the laser beam from the laser light source from the end surface side, and the cross-section of the lens holder so that the shape of the circuit board can also introduce the laser beam. The objective lens assembly according to claim 1, wherein the objective lens assembly has the same shape as the shape.   The lens holder is provided with two focusing coils and one focusing element disposed on both surfaces sandwiching the objective lens, which are orthogonal to the end face to which the circuit board is fixed. 2. The objective lens assembly according to claim 1, wherein the tracking coil is fixed.   The objective lens assembly according to claim 5, wherein two objective lenses are arranged in the lens holder in an arrangement direction of two focusing coils and one tracking coil.   The objective lens assembly according to claim 1, wherein each circuit board has a land for soldering three suspension wires.   A support body, a suspension wire that supports the objective lens assembly so as to be movable in parallel with the support body, and a focusing magnet and a tracking magnet fixed to the support body so as to face the focusing coil and the tracking coil of the objective lens assembly. An optical pickup comprising the objective lens assembly according to claim 1, wherein the objective lens assembly is an optical pickup.

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