JPS6142788A - Pickup arm - Google Patents

Abstract

PURPOSE:To make a member thin, to lighten its weight and to improve the reliability by giving a projection for expanding continuously in the longitudinal direction of a pickup arm from the periphery of a support point at the other end to its top and in the outward control direction from a hollow-like matrix. CONSTITUTION:A pickup arm 2 disposes vertically wing-shaped members 2b and 2b at both ends of an upper matrix of an approximately half a conventional cross-section in the outward direction of a tracking control from an elastic body 6 in the vicinity of a support point at the other end to the side of scanning body 1. Thus the titled arm has the approximately the same rigidity as a conventional one, the resonance frequency about 1.6 times and inertia moment about 0.37 times the conventional one. The arm just made thin to 1/4 ensures the same resonance frequency as the conventional one, however, its rigidity drops to approximately 0.26 times and is far below the conventional one. However, with said way, the weight of the arm is lightened, and its rigidity and reliability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pickup arm of a device, such as a video disc player, which reproduces information signals from a rotating information recording disk, and in particular to a scanner mounted at the tip of the pickup arm. This is an improvement to a pickup device that follows and scans a signal track on an information recording disk to read information signals.

Conventional configuration and its problems Figures 1 to 31'! ! Fig. 1 shows a conventional example of a pickup device of the optical groove type electrostatic force type. The information recording disk of this method has two types of tracking guide signals that alternately sandwich the main information t11 signal, and a third signal that alternately switches the tracking guide signal during tracking control signal processing once per rotation. are recorded, and these signals are extracted as changes in capacitance that occur between the scanning element (in this case, a stylus with an electrode) and an electrode installed thereon. Scanner 1
is attached to the tip of a hollow pipe-shaped pickup arm 2 via a fixing member 3, and a ribbon-shaped lead wire 4 is attached to the scanner 1 (which is connected to a g0 detection circuit). A permanent 1tl1 stone 5 is built into the other end of the arm 2, and its vicinity is supported by a beam-shaped elastic support 6, and both ends of the elastic support 6 are fixed. It is rotatable in the vertical and horizontal directions about the support point of the elastic support body 6, and is also swingable in the longitudinal direction (axial direction) of the pickup arm 2. Three types of electromagnetic coils are disposed around the permanent magnet 5 and are spaced apart from each other, each of which can apply a driving force to the pickup arm 2 in an orthogonal direction. One of the electromagnetic coils is a permanent magnet 5
There is a stylus pressure coil 7 arranged above, which lowers the scanner 1 and applies contact pressure to the information record date aIQ, and a jitter correction coil located on the axis of the permanent magnet 5. 8 and is for driving the scanning element 1 in the tangential direction of the signal track to correct the time difference 1111. Further, there are tracking coils 9a and 9b arranged in a pair with the permanent magnet 5 in between, which drive the scanner 1 in the radial direction of the signal track and perform tracking control. The pickup arm 2 needs to be lightweight and highly rigid from the viewpoint of tracking performance and stability of tracking control, and conventionally a thin-walled tapered pipe with a circular or rectangular cross section is often used. There is. In order for the scanner 1 to sufficiently follow the surface runout of the information recording disk 10, it is necessary to apply a pressing force to the scanner according to the multiplier of the cantilever system's impedance and the speed of the surface runout at the scanning probe position δ. 1, and the peak of the mechanical impedance of the pickup arm system is mainly determined by the mass (or moment of inertia) of the pickup arm system. It becomes necessary to reduce the mass (or tensile moment) of the pickup arm system. Regarding signal 1 - tracking control to follow the eccentricity of the rack, in order to accurately transmit the drive signal to the scanning element (stylus), the higher the resonant frequency of the vibration of the pickup arm itself, the more stable the till becomes.
You can do lit. This is because in order to compensate for the phase delay that normally occurs near the resonance point of the pickup arm, an emphasized drive signal is supplied in the P+ frequency region that includes this resonance point, so the pickup arm's resonance I
This is because if the pickup arm is driven at a frequency that coincides with the Ft point, an oscillation phenomenon occurs and the pickup arm becomes unstable, and the resonance point of the pickup arm needs to be set in a high frequency range where the eccentricity component of the signal track is small. The length of the pickup arm (the length from the elastic support point to the scanning element) is long in order to reduce the floating of the scanning element electrode from the signal surface caused by surface wobbling (fi<Ti). However, if the length of the pickup arm is increased, the quality ff1 (or moment of inertia >'b) will increase, and the resonant frequency of the pickup arm will also decrease. The pickup arm accounts for approximately 70% of the moment of inertia of the pickup arm system, and in order to lower the moment of inertia of the pickup arm system and reduce the effective mass M at the scanning element point, it is essential to make the pickup arm l1ffi. However, with conventional pickup arms, for example, the inner thickness of the vibrator is made thinner, or the cross-sectional area is reduced.
Even if you try to make it fi, the rigidity of the pickup arm will decrease and the resonant frequency will decrease.

Therefore, it is difficult to increase the length of the eaves and increase the rigidity of the conventional pickup arm without changing the material.

Invention 1] The present invention solves the above-mentioned conventional drawbacks, and aims to reduce the weight and increase the rigidity of the pickup arm without changing the material, and improve the ability of the pickup to follow the information recording disk. purpose.

Structure of the invention The above purpose)! In order to achieve this, the pickup arm of the present invention is provided with a scanning element that scans relative to the information recording disk to pick up information signals at one end and a support member that supports this scanning element, and an elastic member near the other end. a pick-up arm having a horizontally supported horizontally rotatable scanning end and further controlling the position of the scanner on the information recording disk in this direction; The pickup arm has a protrusion that extends outward in the control direction from the hollow base body in the longitudinal direction of the pickup arm from the vicinity of the support point to the tip.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on the drawings. In the figure, the same reference numerals as those in the conventional example indicate the same members, and detailed explanation thereof will be omitted.

First, a first embodiment shown in FIGS. 4 to 6 will be described. The pickup arm 2 of the first embodiment has wing-shaped members 2a, 2a extended at right angles to both sides in the tracking control direction outward from the elastic support 6 to the scanner 1 side at the vertically intermediate portion. , 2a, and the wall thickness (plate thickness) is about 1/4 of the conventional thickness. The overall cross-sectional area of the pickup arm 2 in this first embodiment is approximately the same as the conventional cross-sectional area. Next, a second embodiment shown in FIGS. 7 to 9 will be described. In this second embodiment, the base body [pickup arm 2
] On both sides of the upper end, the release members 211 and 2 extend outward in the tracking control direction from the elastic support 6 to the scanner 1 side.
b are arranged at right angles. The thickness of the base plate in this second embodiment is also about 1//I, which is thinner than the conventional one.

Further, both the first and second embodiments have a wing-like member 2a.

The plate thickness of 2a, 2b, 2') is twice the thickness of the other parts (the base body), and it is suitable for cases where the upper and lower parts are divided into two parts, pasted together at the wing part, or drawn from a pipe. I'm considering it.

Comparing the rigidity, resonant frequency, and moment of inertia (trade ff1) of the pickup arm in the tracking v control direction with the conventional type, the rigidity is approximately 1.1 times higher and the resonant frequency is approximately 1.1 times higher in the type of the first embodiment. 6 times, the moment of inertia is about 0.43 times, and even in the type of the second embodiment, the rigidity is about 1 times, the resonance frequency is about 1.6 times, and the moment of inertia is about 0.
37 times more is possible. In these cases, the scanner 1 and 14 fixed member 3 attached to the tip of the pickup
Even considering the influence of nm, the resonant frequency is much higher than the conventional one. However, if the thickness of the conventional pickup arm is reduced to 1/4, the resonant frequency of the single pickup arm remains the same, but the rigidity decreases by about 0.26 times, so the scanner at the tip and the fixing member are Due to the influence of the mass, the resonance frequency of the pink-up system is much lower than that of the conventional system. As described above, according to the above embodiment, the ability of the pickup to follow the information recording disk 10 can be improved with a pickup arm that is lighter and more rigid than the conventional one. According to the invention, the pickup arm is equipped with a scanner for reading information signals from an information recording disk and is driven under tracking control, and has a protrusion whose cross-sectional shape extends outward in the tracking control direction from the hollow base body. By doing so, we were able to make the parts thinner, and the lightest and most rigid pickup system was created by 6%.
The ability to track the vibrations of the information recording disk is improved.
In addition, the 1-racking control range for the signal 1-rack is expanded, and a highly reliable pickup device can be realized as a signal detection device.

[Brief explanation of drawings]

Fig. 1 is a perspective view without showing a conventional pickup device, Fig. 2 is a plan view thereof, Fig. 3 is a sectional view taken along line XX in Fig. 2, and Fig. 4 is a pickup device according to a first embodiment of the present invention. 1" perspective view, FIG. 5 is the same plan view, and FIG. 6 is the Y-Ytlji of FIG. 5.
7 is a perspective view showing the pickup device of the second practical example of the present invention, FIG. 8 is a plan view of the same, and FIG.
-X sectional view. 1...Scanner, 2...Pickup arm, 3...
・Fixing member, 4... Lead wire, 5... Permanent magnet,
6... Elastic support body, 7... Needle pressure coil, 8... Jitter correction coil, 971,911... 1-racking coil, 10... Information recording disk

Claims (1)

[Claims] 1. A scanning element that scans relative to the information recording disk to read information signals is provided at one end, and a support member that supports this scanning element, and the vicinity of the other end is elastically supported so that the scanning element is moved in the horizontal direction. The pickup arm has a structure in which the position of the scanner on the information recording disk is controlled in this direction, and the pickup arm is rotated continuously from the vicinity of the support point at the other end to the tip. A pickup arm having a protrusion extending outward in the control direction from a hollow base body in the longitudinal direction.