JPH0320912Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a pickup device for an optical disc player. FIG. 1 shows an example of an optical system for optically scanning an information recording track to detect information.
The irradiation light flux 3 is guided to an objective lens 7 via a beam splitter 4, a quarter-wave plate 5, a mirror 6, and a rotatable disk 8.
The reflected light obtained by reflection from the disk 8 is again focused by the objective lens 7 to form a reflected light beam 9, and the reflected light beam 9 is sent to a beam splitter. 4, it is separated from the irradiation light beam 3 and deflected toward the focusing lens 10, and then sent to the photodetector 1 via the knife edge 11.
Information is detected from the spot focused on 2. Although the above optical system is built into the housing, it is equipped with a focusing drive mechanism that determines the focal point position and a tracking drive mechanism that determines the scanning spot position, and is used as a pick-up device. It is used in audio disc (DAD) players, etc., and as shown in Fig. 2, the objective lens 7 is supported in a housing 13 by a moving coil type drive mechanism, and the distance from the disc 8 is kept constant according to surface wobbling. It is used for focusing control to move the objective lens 7 up and down in the direction perpendicular to the plane of the figure in order to maintain the focus.Although the entire housing 13 is housed in the frame 14 as shown in Figure 3, the housing surface on the side supporting the objective lens 7 and The facing frame surface 141 and the frame surface 142 facing the casing surface located on the opposite side of the casing surface are fixedly supported via elastic bodies, and rubber legs 1 are provided on the frame surface 141 side.
51, 152, 153, and rubber legs 151', 15 on the side of the frame surface 142 whose supporting parts on the frame face the rubber legs 151 to 153, respectively.
2', 153', an electromagnetic driving means 18 consisting of a solenoid coil 16 fixed to the casing 13 shown in FIG. The specific mechanism is to move the objective lens 7 from the reference position of the housing 13 in the forward and reverse arrow directions in the figure against the elastic return force of the rubber legs, and to control tracking. As an example, according to this type of support,
Since the focusing drive and tracking drive are separated and the structure is simple, it has the advantage of being miniaturized. However, since the above-mentioned tracking control mechanism is supported only by rubber material, the hysteresis (distance between A and B in the displacement characteristics of the pick-up position shown in FIG. 6) is large when driving the housing 13. Moreover, the frequency characteristics also had the disadvantage that unnecessary peaks were likely to occur as shown in FIG. 7 because the rotation axis was not determined. There is also a method of determining the rotational axis by providing a shaft 19 as shown in Fig. 4, but in order to drive the casing 13, the gap between the coil and the magnet is increased in order to rotationally bias it in the direction of the arrow in the figure. Because of this, it is difficult to obtain a large driving force, and since the housing 13 moves in a complete circle around the shaft 19, the stroke amount at the pick-up position in the disk radial direction (tracking direction) is not as large as the configuration shown in Figure 2. However, it is not suitable for downsizing the housing. The present invention has been made to eliminate the above-mentioned drawbacks, and an embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows the pick-up device of this embodiment, and the same numbers refer to the configuration in FIG. The second type of rubber legs 20B and 20C are provided, and the frame body 1 is provided with
Similarly, the housing 13 is provided on the 42nd side in a corresponding manner.
Seed rubber leg 20A and second type rubber leg 20B, 2
It is supported to the frame 14 by 0C. However, since the rubber legs 20B and 20C have a lower rubber hardness than the rubber leg 20A, that is, they are more deformable, so in order to effectively drive the casing, the rubber legs 20B and 20C are supported closer to the electromagnetic drive means 18 than the support point of the rubber leg 20A. It is set up separately. The above configuration allows the support point of the rubber leg 20A to be a pivot point (because the rubber hardness is high, the rubber material is deformed in the direction of being driven even though it resists the force) by creating a difference in hardness between the rubber legs. (Since this occurs to some extent, the configuration is different from a rotating shaft such as a shaft that does not have axis misalignment.)
In addition, the rubber legs 20B and 20C are largely deformed for use in driving the casing, and the frequency characteristics are improved, and the return force of the rubber leg 20A is not used to substantially drive the casing due to deformation of the rubber material. The rubber legs 20B and 20C used for driving are forcibly returned to their original positions, thereby reducing hysteresis. If the rubber leg 20A is brought close to the driving means, the inherent hysteresis of the rubber leg 20A itself will deteriorate the drive characteristics, so it is desirable to keep the rubber leg 20A separated from the drive means, and this is effective in increasing the stroke. Next, the hysteresis and maximum sensitivity stroke (excitation current ±400 mA) were measured at the same support location according to the experimental example shown in Table 1, and the results are shown in Table 2.

【table】

[Table] In the conventional example, the support is unstable due to low rubber hardness, making it impossible to measure.In the conventional example, the stroke amount cannot be large, and as in the comparative example, the supporting point of the first type rubber leg is placed on the frame surface 141. If there are two locations,
Hysteresis increases and frequency characteristics range from 100 to
It became clear that there was a large disturbance around 300Hz,
That is, as in the embodiment, there is at most one rubber leg support location on the same surface of the frame, in other words, on a predetermined axis (in the case of FIG. 151-151' direction), the above effect can be obtained. As described above, the pick-up device of the present invention uses the first type rubber legs and the second type rubber legs, which have a lower hardness than the first type rubber legs, to support the pick-up housing containing the optical system to the frame. The frame has a leg and an electromagnetic drive means for tracking control that drives the casing, and the first type rubber leg is used as a substantially rotational fulcrum of the pick-up casing driven by the electromagnetic drive means. The first type of rubber leg is disposed at a position facing the electromagnetic drive means, and the first type of rubber leg is disposed on the frame surface on which the first type of rubber leg is disposed at a position closer to the electromagnetic drive means than the position where the first type of rubber leg is disposed. By arranging two types of rubber legs, the frequency characteristics are improved, hysteresis is reduced, and the stroke amount is also increased, which is practically effective.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the optical system, Figs. 2 and 4 are plan views of a conventional pick-up device, Fig. 3 is a side sectional view of the main parts of a conventional example, and Fig. 5 is a diagram of a pick-up device according to an embodiment of the present invention. A plan view, FIG. 6 is a diagram showing the displacement characteristics of the pickup device, and FIG. 7 is a diagram showing the frequency characteristics. Explanation of symbols, 13...Pick-up housing, 14
... Frame body, 18 ... Electromagnetic drive means, 20A ... First type rubber legs, 20B, 20C ... Second type rubber legs.

Claims (1)

[Scope of utility model registration request] A first type of rubber leg for supporting the pick-up housing containing the optical system on the frame, and a second type of rubber leg having a lower hardness than the first type of rubber leg, and a tracking control for driving the housing. and an electromagnetic drive means, wherein the first type rubber leg is disposed at a position facing the frame so as to be a substantially rotational fulcrum of the pick-up casing driven by the electromagnetic drive means;
The second type of rubber leg is disposed on the frame surface on which the first type of rubber leg is disposed at a position closer to the electromagnetic drive means than the position of the first type of rubber leg. A pick-up device.