JPH0538411Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a tracking device for an optical pickup used in, for example, a CD player (compact disc player).

(Prior art) In this type of optical pickup, a lens for reading information recorded on a disk is attached to a coil bobbin around which a focus coil and a tracking coil are wound. Focus adjustment and tracking adjustment are performed by moving the and tracking parts in a magnetic field formed by a common magnetic circuit. The focus coil is wound around the entire circumference of the coil bobbin, and the tracking coil is divided into a plurality of pieces and wound.

To explain the winding structure of a conventional tracking coil with reference to Fig. 3, 1 and 2 are the magnetic poles of magnets provided at opposing positions, and both have N poles with opposing surfaces having arc shapes. It is. A coil bobbin 4 that rotates around a shaft 3 is provided between these magnetic poles 1 and 2 via a sleeve 5. A lens 6 is attached to the coil bobbin 4 to emit a laser beam to a disk such as a CD (not shown) and to receive the laser beam reflected by the disk. A focus coil 7 is wound around the entire outer circumference of the coil bobbin 4, and tracking coils 8a, 8b, 8c, and 8d divided into four pieces are arranged at equal intervals around the outer circumference of the coil bobbin 4. It is wound so that it faces the end of 2. As a result, the focus coil 7 is wound around the outer circumference of the coil bobbin 4, and the tracking coil 8 is divided into four pieces.
a, 8b, 8c, and 8d rotate around the shaft 3 in a magnetic field forming a common magnetic circuit, and also slide in the axial direction of the shaft 3.

(Problem to be solved by the invention) In the conventional optical pickup tracking device with such a configuration, four tracking coils are required. I had a problem with it being difficult to put on. Also, electrically, four coils 8a, 8b, 8c, each wound separately,
8d is connected at multiple points, such as the middle part 9 and the both end parts 10, as shown with circles in FIG. There was also the problem that incorrect wiring was likely to occur because the wiring was not consistent. The present invention was made with the aim of solving these problems.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention changes the structure of an optical pickup tracking device to a cylindrical structure with a lens partially attached between opposing magnetic poles. A coil bobbin is supported rotatably around a shaft and slidably in the direction of the shaft, and a focus coil for adjusting the focus of the lens is wound around the outer periphery of the coil bobbin. In an optical pickup having a tracking coil wound around the outer periphery for tracking the coil bobbin, the opposing magnetic poles are made to have opposite polarities, and the focus coil is arranged in a figure 8 shape with a part of the coil bobbin as a boundary. The tracking coil is wound around the outer periphery of the focus coil wound in a figure 8 shape, and a tracking coil formed by two coils each having a length that reaches the opposing magnetic poles is wound. be.

(Function) With this configuration, it is possible to drive in the axial direction in the same way as the conventional one shown in Fig. 3 in radially opposing magnetic fields, and furthermore, the two tracking coils , it is possible to perform adjustment with the same performance as the conventional four tracking coils. Further, it becomes easier to attach the tracking coil to the coil bobbin, and the number of connection points is reduced, so that the assembling workability is significantly improved.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIG. 1. In the embodiment of the present invention, the polarity of the magnetic poles 11 and 12 are changed, and the magnetic pole 13 is located between them and rotates around the shaft 13. The tracking coils attached to the outer periphery of the coil bobbin 14 are denoted by reference numerals 18a and 18.
It is divided into two parts as shown by b. The tracking coil 18 is divided into two parts.
a and 18b are long enough to reach opposing magnetic poles 11 and 12 of opposite polarity, respectively, and as shown by reference numerals 19 and 20 in FIG. Connected. In this device, since the magnetic poles 11 and 12 are of opposite polarity, it would be inconvenient to wind the focus coil 17 in a fixed direction as in the conventional device. Therefore, as shown by reference numeral 21 in FIG.
The focus coil 17 is wound in a figure eight shape). In FIG. 1, reference numeral 15 indicates a sleeve, and reference numeral 16 indicates a lens.

In this tracking device configured in this way, the focus coil 17, which is wound in a figure-eight shape, acts on the magnetic field generated by the magnetic poles 11 and 12 so as to partially intersect with the magnetic field. At the same time, two tracking coils 18a, 18 wound around the outer circumference of the tracking coil 18a, 18
Tracking adjustment is performed by b. As for manufacturing problems, since the tracking coil is divided into two pieces and the size of each piece is large, it becomes extremely easy to attach the tracking coil to the coil bobbin 14. Furthermore, since the number of connection points is reduced, the connection work becomes extremely easy. Furthermore, by setting the polarity of the magnetic poles to be opposite to those of the opposing magnetic poles, and by making the length of the tracking coils reach the respective magnetic poles, the tracking performance was improved as shown in Figure 3. It can be made to the same extent.

(Effects of the invention) Since the invention is constructed as explained above, in a magnetic field where the focusing and tracking uses a common magnetic circuit, two tracking coils can be used instead of the conventional four. This means that tracking adjustments can be made in the same way. Therefore,
It is possible to obtain an optical pickup tracking device with a small number of parts and excellent assembly workability.

[Brief explanation of the drawing]

Fig. 1 is a front view of one embodiment of the present invention, Fig. 2 is an explanatory diagram explaining the connection of the one in Fig. 1, Fig. 3 is a front view of the conventional one, and Fig. 4 is the connection of the one in Fig. 3. FIG. 11, 12...Magnetic pole, 13...Shaft, 14
...Coil bobbin, 18a, 18b...Tracking coil.

Claims (1)

[Scope of utility model registration request] A cylindrical coil bobbin with a lens partially attached is supported between opposing magnetic poles so as to be rotatable about an axis and slidable in the direction of the axis, and the focus adjustment of the lens is provided on the outer periphery of the coil bobbin. In an optical pickup in which a focus coil for tracking the coil bobbin is wound around the outer periphery of the focus coil, the opposing magnetic poles are made to have opposite polarities, and the A focus coil is wound in a figure 8 shape with a part of the coil bobbin as a boundary, and two windings of length reaching the opposing magnetic poles are placed around the outer periphery of the focus coil wound in a figure 8 shape. A tracking device for an optical pickup characterized by winding a tracking coil formed of a coil.