JP2011086376A - Objective lens driving device and method of forming protector in objective lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve a problem wherein a height of a protector formed by a viscosity change of liquid during coating, a pressure change of a dispenser when administering the liquid, an amount change of coating due to choke of a needlepoint for extracting the liquid, or an environmental change such as temperature and humidity for hardening the liquid when forming the protector by coating the liquid having hardening property changes. <P>SOLUTION: The method includes: forming a plurality of protectors 10 protruding from a periphery of an objective lens 2 by hardening the liquid having a hardening property while being stayed by its viscosity on an upper face of a lens holder 1; and regulating the height of the protector 10 by pushing the protector 10 in process of formation to a regulating plate 11 when the liquid is half hardened. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for forming a protector in an objective lens driving apparatus, which shows a method for forming a protector for protecting an objective lens and a signal recording medium by projecting a plurality of projections around the objective lens on the upper surface of a lens holder. The present invention relates to a method for forming a protector in an objective lens driving device formed by curing.

  As is well known, in an objective lens driving device in an optical head that optically reads or writes signals on a signal recording medium such as a disk, the lens holder on which the objective lens is mounted is elastically supported such as a support wire. Focus control and tracking control of the light beam which is elastically supported by the member so as to be displaceable with respect to the actuator frame, and is converged by the objective lens by driving the lens holder, is performed on the signal recording medium. Yes.

  Incidentally, in order to reduce the light spot diameter on the signal layer of the signal recording medium as the capacity of the signal recording medium is increased, the objective lens for high density needs to have a large NA. On the other hand, in order to cope with an increase in the speed of the signal recording medium, weight reduction of the movable part of the actuator is promoted. Therefore, increasing the NA without increasing the diameter of the objective lens used increases the working distance that the lens holder can operate in the focus direction until the objective lens comes into contact with the signal recording medium. ing.

Therefore, the objective lens drive device prevents the objective lens and the signal recording medium from being damaged due to the objective lens colliding with the signal recording medium due to the displacement or impact of the objective lens in the optical axis direction when the focus servo is introduced. As described above, there is known a device in which a protector that protrudes closer to the signal recording medium from any part of the lens holder including the objective lens is provided around the objective lens. (For example, see Patent Document 1)
By the way, as a protector, as shown in Patent Document 1, the hardness is lower than that of a polycarbonate used as a material of a signal recording medium, for example, a transparent substrate that is a base material of DVD or CD, and other characteristics such as vibration proofing. Silicone rubber may be used. As this silicone rubber, there is a liquid agent type having curability. It is conceivable that this liquid agent type silicone rubber is applied around the objective lens on the upper surface of the lens holder, and this silicone rubber is cured to form a protector.

JP 2001-319355 A

  However, when a protector is formed by applying a curable liquid, the amount of liquid applied due to changes in the viscosity of the liquid during application, pressure changes in the dispenser that administers the liquid, or clogging of the needle tip from which the liquid is extracted Or the height of the protector formed is changed by various factors such as environmental changes such as temperature and humidity at which the liquid agent is cured.

  As a result, there arises a problem that the height of the protector deviates from the standard height, the working distance is reduced, or the height of the protector is insufficient to prevent the objective lens from contacting the signal recording medium.

  Further, although a plurality of protectors are formed around the objective lens of the lens holder, there is a problem that the protection performance for protecting the signal recording medium and the objective lens from collision is inferior due to the variation in height of each protector.

  The present invention forms a plurality of protectors protruding around the objective lens by curing a liquid agent having a curable property on the upper surface of the lens holder while retaining the viscosity, and forming the liquid agent in a semi-cured state The height of the protector is regulated by pressing the protector on the way against the regulating plate.

  According to the method for forming a protector in the objective lens driving device of the present invention, the height of the protector is regulated by pressing the protector that is in the process of being formed into a semi-cured state against the regulating plate. It is possible to make the height of the standard, and the height of a plurality of protectors can be easily made uniform, and the tip of the protector is crushed and the contact area with the signal recording medium is expanded. This is advantageous in improving the protection performance for protecting the signal recording medium and the objective lens from collision.

  In this case, since the lens holder is turned upside down and the protector in the middle of formation in which the liquid agent is in a semi-cured state is pressed against the regulating plate, workability is good.

  Further, since the height of the protector is defined from the upper surface of the rim portion of the objective lens, the contact portion with the signal recording medium can be reliably used as the protector.

  In addition, since the liquid agent is applied on the adhesive that adheres and fixes the objective lens, it is possible to secure a place to apply the liquid agent by reducing the size of the lens holder, and to form holes and grooves formed so as to collect the adhesive. It can be expected to apply the liquid using the shape.

  In this case, when the adhesive is an acrylic UV type adhesive and the liquid agent is a silicone rubber type, the material of the adhesive and the liquid agent does not interfere with each other to inhibit curing, and the liquid agent is placed on the adhesive. Adhesion can be achieved with an adhesive strength greater than the desired strength.

It is a perspective view which shows the completion state of an example of the objective lens drive device with which the protector was formed by the formation method of the protector in the objective lens drive device which concerns on this invention. It is a schematic diagram of the lens holder 1 part from the side surface which shows the state which presses each protector 10 in the middle of formation to the control board 11. FIG. It is a schematic diagram of the lens holder 1 part from the side surface showing the state after each protector 10 being formed is pressed against the regulating plate 11. It is a perspective view which shows the objective lens drive device of the state in which each protector 10 is not formed.

  FIG. 1 is a perspective view showing a completed state of an example of a DVD and CD-compatible objective lens driving device in which a protector is formed by the protector forming method in the objective lens driving device according to the present invention.

  An objective lens 2 is attached to the lens holder 1, the focusing coil 3 is wound around the lens holder 1 so as to surround the entire circumference of the lens holder 1, and tracking is arranged at the four corners of the lens holder 1. Each coil 4 is wound.

  The four suspension wires 5 that support the lens holder 1 are respectively fixed at one end to a wiring board 7 fixed to the actuator frame 6, and the other end side is from above and below the center of two predetermined side faces of the lens holder 1. It is fixed to each support portion 8 that protrudes.

  Thus, the lens holder 1 is elastically supported by the four suspension wires 5 so as to be displaceable in the focus direction and the tracking direction on the actuator frame 6. In this case, two suspension wires 5 are arranged on both sides of the lens holder 1 and are laid in a letter C shape in parallel in the vertical direction and in the horizontal direction.

  Further, on the tip of the other end side of each suspension wire 5 fixed to the lens holder 1, each projecting piece 9 to which a predetermined terminal of each driving coil of the focusing coil 3 and the tracking coil 4 is entangled is attached to the lens holder 1. The suspension wires 5 are integrally formed, and the vicinity of the tip on the other end of each suspension wire 5 is soldered, and one end of each suspension wire 5 is soldered to a land of the wiring board 7. The supplied focus and tracking control signals are supplied to the drive coils via the suspension wires 5.

  Further, the actuator frame 6 has an effective magnetic field on the effective side of each drive coil in a state where the lens holder 1 is installed and supported at a predetermined position by four suspension wires 5 (two below the two sides are not shown). Is provided with a magnetic circuit. Therefore, by supplying a focus control signal to the focusing coil 3, the objective lens 2 is driven in the focus direction via the lens holder 1 in accordance with the focus control signal, and each tracking coil 4 is By supplying a tracking control signal, the objective lens 2 is driven in the tracking direction via the lens holder 1 in accordance with the tracking control signal.

  Next, in the objective lens driving device configured as described above, the protector which is a characteristic part of the present invention will be described in detail.

  On the upper surface of the lens installation portion 1a on which the objective lens 2 of the lens holder 1 is installed, protectors 10 are formed in a dome shape around the objective lens 2 at the four corners of the lens installation portion 1a. Each protector 10 protrudes from the other side of the actuator movable portion (the upper surface of the rim portion 2a of the objective lens 2) and faces the disk. It is said.

  Here, each of the protectors 10 is made of silicone rubber, and has a lower hardness than the polycarbonate of the base material of the disk. The protectors 10 are caused by displacement or impact in the optical axis direction of the objective lens 2 when the focus servo is introduced. Even if it collides with the disc, the disc is prevented from being damaged.

  Further, the protector 10 has a height in consideration of the deformation so that the objective lens 2 is prevented from coming into contact with the disc even if the protector 10 is deformed by coming into contact with the disc. Is also prevented.

  If each protector 10 is made of silicone rubber, it can be expected that the higher-order resonance characteristics of the actuator will be improved due to the vibration-proof property of the silicone rubber.

  Next, a method for forming each protector 10 will be described.

  Each protector 10 is formed by curing a curable silicone rubber-based liquid in a state where the liquid is retained by viscosity. Examples of the liquid include a room-temperature-curing liquid RTV (Room Temperature Vulcanizing) rubber (product name: KE3494, Shin-Etsu Chemical Co., Ltd.) is used.

  The silicone rubber-based liquid agent is applied to a predetermined portion around the objective lens 2 on the upper surface of the lens holder 1, and in this state, the silicone rubber-based liquid agent is cured to such an extent that the surface does not become sticky and the inside is not cured. Set to a cured state. The liquid RTV rubber in the above example becomes semi-cured after about 10 minutes.

  Each protector 10 in the middle of formation, in which the silicone rubber liquid solution is in a semi-cured state, is pressed against the regulating plate 11 with the lens holder 1 turned upside down as shown in the schematic diagram of FIG. The restricting plate 11 is made of carbon steel for mechanical structure, and has a structure in which a protrusion 11b that comes into contact with the upper surface of the rim of the objective lens 2 attached to the lens holder 1 is provided on the flat plate 11a. The height h of 11b becomes a height prescribed | regulated from the rim | limb part 2a upper surface of the objective lens 2 in each protector 10. FIG.

  When each protector 10 in the process of being formed in a semi-cured state is pressed against the restriction plate 11 so that the upper surface of the rim 2a of the objective lens 2 is brought into contact with the protrusion 11b of the restriction plate 11, a schematic diagram shown in FIG. As described above, the protectors 10 being formed are crushed at their tips due to their plasticity. Therefore, each protector 10 is regulated to a height that is higher than the upper surface of the rim portion 2a of the objective lens 2 by a height h. The height h is set to 0.15 mm, for example, and each protector 10 is defined to be 0.15 mm higher than the upper surface of the rim portion 2a of the objective lens 2. Then, the tip of each protector 10 is flattened and the contact area with the disk is enlarged.

  By the way, each protector 10 is formed on an adhesive applied to adhere and fix the objective lens 2 to the lens holder 1.

  FIG. 4 is a perspective view showing the objective lens driving device in a state where each protector 10 is not formed. When adhering the objective lens 2 to the lens holder 1, the objective lens 2 is installed by adjusting the optical axis at a predetermined position of the lens installation portion 1a of the lens holder 1, and the objective lens 2 is adjusted in the optical axis. The acrylic UV (ultraviolet) adhesive 12 stored in each hole formed around the objective lens 2 at the four corners of the lens installation portion 1a is cured by UV irradiation.

  The silicone rubber-based liquid that forms each protector 10 is applied onto an adhesive 12 that adheres and fixes the objective lens 2 to the lens holder 1. Therefore, it is not necessary to form in the lens holder 1 a site suitable for forming each protector 10 around the objective lens 2 as a dedicated site for applying the silicone rubber liquid. And, by appropriately selecting the material of the adhesive that bonds the objective lens 2 to the lens holder 1 and the material of the liquid that forms each protector 10, the material of the adhesive and the liquid do not interfere with each other to inhibit curing, The liquid agent can be bonded onto the adhesive with an adhesive strength higher than the desired strength.

  In the above-described restriction plate 11, the protrusion 11 b that abuts on the upper surface of the rim of the objective lens 2 is used to restrict the height of each protector 10. It is possible to regulate the height of each protector 10 on the basis of the upper surface of the lens holder 1 by providing a protrusion that contacts the upper surface of the lens holder 1, and the lens when the protector 10 is pressed against the regulating plate 11. It is also possible to regulate the height of each protector 10 by defining the movement distance of the holder 1.

DESCRIPTION OF SYMBOLS 1 Lens holder 1a Lens installation part 2 Objective lens 2a Rim part 10 Protector 11 Control board 11b Protrusion part

Claims (5)

In an objective lens driving device in which a lens holder to which an objective lens is attached on an upper surface side facing a signal recording medium is elastically supported by an actuator frame so as to be displaceable, a curable liquid agent is retained on the upper surface of the lens holder by viscosity. The protector is cured in a cured state to form a plurality of protectors that protrude around the objective lens, and the height of the protector is regulated by pressing the protector that is in the process of being semi-cured against the regulating plate against the regulating plate. A method for forming a protector in an objective lens driving device. The method for forming a protector in an objective lens driving device according to claim 1, wherein the protector in the process of forming the liquid agent in a semi-cured state is pressed against the regulating plate by turning the lens holder upside down. The restriction plate is provided with a protrusion abutting on the upper surface of the rim portion of the objective lens mounted on the lens holder, and the height of the protrusion is defined from the upper surface of the rim portion of the objective lens in the protector. A method for forming a protector in the objective lens driving device according to claim 1. The method for forming a protector in an objective lens driving device according to claim 1, wherein the liquid agent is applied on an adhesive that adheres and fixes the objective lens. 5. The method of forming a protector in an objective lens driving device according to claim 4, wherein the adhesive is an acrylic UV adhesive and the liquid agent is a silicone rubber.

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