KR910003456B1 - Laser pick-up unit - Google Patents

Abstract

Laser pick-up reading an information recorded on compact disk is composed of focusing coil (8), tracking coil (20), yoke (22) and magnet (30). These are arranged at right angle to the center line (G) connecting the center of object lens (4) and supporting shaft (8). The focusing coil (18) and trackaing coil are installed at the innerside of bobbin (2). The magnet (30) is fixed to the bottom of yoke (22). Two ironcore of yoke are situated on the innerside of tracking coil. This apparatus has an advantage of high quality achieved by excluding the mutual effect of the data track tracking and focusing tracking and simple structure.

Description

Laser pickup structure

1 is an exploded perspective view showing an embodiment of the present invention.

2 is a cross-sectional plan view of the assembled state of FIG.

3 is an X-ray side cross-sectional view of FIG.

4 is a plan sectional view showing a modification of the present invention.

Fig. 5 is a side cross-sectional view showing a modification of Fig. 4.

6 is a flat shaving showing another embodiment of the present invention.

7 is a side cross-sectional view showing a modification of FIG.

* Explanation of symbols for main parts of the drawings

2: bobbin 8: support shaft

12: coil insertion hole 16: balance weight

18: focus coil 30: magnet

30 ', 30 ": bar magnet 22: yoke

220: arched yoke 300 ': rod magnet

300: ring magnet G: center line

200: Arched tracking coil 180: Arched focus coil

The present invention relates to a laser pickup structure. Laser pickup is a device for reading information recorded on a compact disc, and is widely used in audio equipment or video industry equipment.

The information recorded on the compact disc is usually described in digital code, and the laser pickup which reads it out is adapted to receive the laser beam reflected from the disc and determine its signal; It is necessary to ensure that the focus of the beam can always be matched and that the track can be precisely tracked even if the disk vibrates during operation.

In general, in the laser pickup, the beam focusing motion needs to be shifted by ± / mm in the direction of the optical axis and the tracking motion by ± 0.5mm in the left and right directions. Therefore, a magnet mainly composed of magnets, yokes, tracking coils and focusing coils is used. The circuit is adopted as the driving means.

By the magnetic circuit described above, the bobbin mounted with the objective lens swings up and down and to the left and right, and the bobbin is usually supported by a spring or a shaft.

The former spring supporting method is a moving coil type in which a focus coil and a tracking coil are mounted on the outer surface of the bobbin, a yoke and a magnet are arranged on the outer circumference of the bobbin, and a magnet is mounted on the outer surface of the bobbin, and a yoke on the outer circumference. And a moving magnet type in which a focus coil and a tracking coil are arranged. The latter shaft support method includes an optical path type for positioning an objective lens inside the focus coil and the tracking coil in the bobbin, on the outer side of the focus coil and the tracking coil. There is an external light path type for positioning the objective lens.

However, the conventional laser pickup drive structure described above exhibits the following problems as is well known.

The spring support method depends on the spring force of the tracking driving force, and the vibration is severe during tracking, which causes a bad effect on the sound equipment or the video industry.

The shaft support method is a structure in which the tracking coil, focus coil, magnet, and yoke are arranged on the left and right of the center line connecting the optical axis and the support axis, but it is a relatively stable method, but the focus coil and the tracking coil are wound around the bobbin outer circumference of small size. Due to technical difficulties in the process, the precision of the bobbin cannot be secured, and there is a tendency for the ubiquitous phenomenon of the bobbin to occur on the support shaft after assembly.

The present invention is to provide a laser pick-up structure of a simple structure, easy to assemble, without bias of the bobbin and shaking during operation in order to solve the above-mentioned defects seen in the conventional laser pickup structure.

According to the present invention, the focus coils, the yokes, the magnets, and the tracking coils are arranged at right angles to the center lines, while the centers of the bobbins are centered on the center line connecting the optical axis of the bobbin and the focus coils. And the tracking coil is mounted on the inside of the bobbin, characterized in that the magnet is configured to be fixed to the inside of the yoke.

In the present invention, the bobbin can have a counterweight on the opposite side of the objective lens, in this case it is possible to obtain a more accurate center of rotation.

In addition, the magnet may be integrally installed on the support shaft, and for this purpose, a magnet in which a shaft hole is drilled in the center or a magnet having a support shaft extended to the bottom may be used.

The present invention described above is manufactured by winding the focus coil and the tracking coil through a separate process, and then attaching it to the inside of the bobbin, which is easy to manufacture, and the mass center of all parts is connected to the center of the objective lens and the center of rotation of the bobbin. By arranging them in line with each other, the bobbin uneven phenomenon does not occur.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view showing an embodiment of the present invention, in which 2 denotes a bobbin.

At one end of the bobbin 2 is inserted an insertion hole 6 in which a conventional objective lens 4 is mounted, and has a shaft hole 10 through which the support shaft 8 is inserted. A pair of coil insertion holes 12 are formed to face each other about the axial hole 10 in the direction orthogonal to the center line G connecting the center of the objective lens 4 and the center of the shaft hole 10, Moreover, the flaw 14 is carved on the opposite side to which the objective lens 4 is mounted in the bobbin 2. The flaw 14 is attached with a counterweight 16 having a weight comparable to that of the objective lens 4 described above so that the center of gravity of the bobbin 2 is held by the support shaft 8.

The centering of the bobbin 2 may be performed by forming the thickness of the portion of the flaw 14 to give a weight.

A pair of focus coils 18 are mounted inside the coil insertion hole 12 described above. Both of the focus coils 18 are manufactured by winding through a separate process in a form corresponding to the inner circumferential surface of the coil insertion hole 12, and in this embodiment, the hollow coil is hollow.

On the other hand, a pair of tracking coils 20 are mounted in the bobbin 2 at a position orthogonal to the center line G with respect to the shaft hole 10. Similar to the focus coil 18, the tracking coil 20 is also manufactured by winding a separate process. In this embodiment, a winding coil of a so-called saddle type is used.

As described above, the bobbin 2 having the focus coil 18 and the tracking coil 20 mounted therein is covered above the yoke 22 to be pivotally supported by the support shaft 8.

The support shaft 8 is fixed to the base 24 through the central shaft hole 23 of the yoke 22, and the bobbin 2 pivots or lifts the support shaft 8 to a point.

자상을 이루고 있다.The yoke 22 is fixedly attached to the base 24 like a conventional laser pickup, but its shape is upwardly from the bottom 26 so that the yoke 22 can be inserted into the inner space held by the pair of focus coils 18. Cross section with iron core 28 extending side by side

Caring for.

Before covering the bobbin 2 above the yoke 22, the magnet 30 is fixed to the bottom 26 of the yoke 22.

The magnet 30 is located inside the tracking coil 20 described above, and in this embodiment, one pair is arranged symmetrically around the support shaft 8.

FIG. 2 is a plan sectional view showing the assembled state of FIG. 1, in which the tin core 28 and both magnets 30 of the yoke 22 are centered about the support shaft 8 by the assembling process as described above. It is shown orthogonal to ().

Both iron cores 28 of the yoke 22 are inserted into the inner space of the focus coil 18 attached to the inner circumferential surface of the coil insertion hole 12 to induce the direction of the magnetic field, and the bottom of the yoke 22 ( The magnet 30 fixedly installed at 26 is located inside the tracking coil 20 around the center line G, so that the magnetic field in the magnet 30 is formed parallel to the center line G, thereby forming both coils 18. (20) will be affected.

By such a configuration, the tracking force appears as a right force orthogonal to the center line G, and the focusing force appears in the vertical direction of the support shaft 8.

When tracking and focusing forces occur, the bobbin 2 swings left and right on the support shaft 8 because the bobbin 2 is pivotably supported about the support shaft 8 above the yoke 22 as shown in FIG. Lifting exercise will be performed.

Referring to the focusing and tracking motion of the bobbin shown in the present invention in more detail as follows. When the focus coil 18 is energized, a magnetic circuit is formed, and the polarity of the magnetic field changes according to the current direction. Therefore, the bobbin 2 is repelled or attracted to the yoke 22 according to the polarity of the focus coil 18, which is represented by the movement of lifting up and down the support shaft 8. This process is performed until the objective lens 4 is in focus.

Like the focusing movement, the tracking movement is performed by the suction-repulsion of the magnetic field generated by energizing the tracking coil 20. The tracking movement only fluctuates from side to side, whereas the focusing movement is up and down.

In this example, two magnets 30 are used, but FIG. 4 shows an improved variant using a single bar magnet 30 'having a support shaft insertion hole 8' in the center thereof. .

In this variant, the support shaft 8 is fixed to the base 24 through the through hole 8 'of the bar magnet 30'.

When the single bar magnet 30 'is used, the number of parts handled in the assembly is reduced, so that the process proceeds more quickly.

FIG. 5 further shows that the bar magnet body 30 ", which has a fixed shaft 8 ", is formed on the bottom thereof as a further improvement of the fourth embodiment.

Although this modification can obtain the process advantage that the assembly of the support shaft 8 can be omitted, it requires a separate support means capable of stably supporting the bobbin 2.

6 is a plan sectional view showing another embodiment of the present invention. In this embodiment, the ring-shaped magnet 300 is disposed around the support shaft 8 supporting the bobbin 2, and the arcuate tracking coil 200 is disposed on the outer circumference thereof, while the ring-shaped magnet 300 is described above. It is mounted to the arched yoke 220, by arranging the arcuate focus coil 180 on the outer peripheral side to ensure that the left and right oscillation smoothly when tracking the bobbin (2). According to this embodiment, a more accurate tracking effect can be obtained.

FIG. 7 is a side cross-sectional view showing a modification of FIG. 6, in which the bobbin support shaft 8 supporting the bobbin 2 is omitted and the bobbin 2 is supported by the rod-shaped magnet 300 '. Indicates. According to this embodiment, since the support shaft 8 is not required, the parts can be reduced, and the assembly process can be further simplified.

In particular, since the bobbin 2 is supported by the rod-shaped magnet 300 'in the axial form, unlike the example of FIG. 5, it does not require a separate means for the support of the bobbin 2.

As described above, the present invention has a concise configuration of all the components necessary for the laser pickup, and thus, the assembly state is easy and the support state of the bobbin is extremely stable, so that vibrations and ubiquitous phenomena seen in the conventional laser pickup do not occur.

Claims (5)

While matching the center of mass of the focus coil 18, the tracking coil 20, the yoke 22, and the magnet 30 on the center line G connecting the center of the objective lens 4 with the center of the support shaft 8, They are arranged so as to be orthogonal to the center line G, and the above-described focus coil 18 and tracking coil 20 are mounted on the inside of the bobbin 2, and the magnet 30, which has been described above, is mounted on the yoke 22. It is fixed to the bottom 26 of the yoke 22, both iron cores 28 of the yoke 22 is configured by combining the inner space of the focus coil 18 and the magnet 30 is located inside the tracking coil 20. A laser pickup structure characterized by the above-mentioned. The magnet (30) of claim 1, wherein the magnet (30) attached to the bottom (26) of the yoke (22) holds a through hole (8 ') through which the support shaft (8) penetrates. Laser pickup structure, characterized in that consisting of. The laser pickup structure according to claim 1, wherein the magnet (30) is composed of a bar magnet (30 ") extending from the bottom thereof to a fixed shaft (8"). The magnet 30 is a ring-shaped magnet 300 inserted into the outer circumference of the support shaft 8, and the ring-shaped magnet 300 is fixedly attached to the arc-shaped yoke 220, respectively. Laser pickup structure, characterized in that configured to be located inside the tracking coil (200) and the arched focus coil (180). The laser pickup structure according to claim 4, wherein the bobbin (2) is supported by using the ring magnet (300) as the rod magnet (300 ').

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