JPS58115656A - Optical disk device - Google Patents

Abstract

PURPOSE:To obtain a device which inputs and output information smoothly, in interlocking a tracking actuator with an optical head actuator, by using a pulse motor which is manufactured at low cost. CONSTITUTION:In a figure, 1 is a rotary recording medium (disk) and 20 is an optical head. In this optical head 20, a condenser lens 2 supported by a spring, rubber 4, etc., is coupled with a VCM3 and moved in a radius direction by a driving circuit to perform tracking control. A current detection resistance 7 detects a driving current and a low-pass filter 8 cuts unnecessary components to obtain an output proportional to the mean flection extent of the spring. This output is passed through the circuit consisting of comparator circuit 9 and 10 and reference voltage setting circuits 11 and 11' to constitute the circuit which detect the mean flection extent of the supporting spring 4 is too close to an inner side or outer side. Gate circuits 21 and 22 are opened by its output and the output of an oscillating circuit 14 is sent to a stepping motor driving circuit 13 to move an optical head 20 in such a direction that the flection extent of the spring is canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an optical disk device, and more particularly to an access mechanism for moving the entire optical head in the radial direction of a rotating recording medium (disk).

(2) Prior art and problems In optical disk devices, there are
Focus control that always focuses the light on the medium, and tracking control that always focuses the light spot on the target track in response to eccentricity, are indispensable. Among these, tracking control is normally as shown in FIG. 1(a)K.

The lens 2 is moved in the radial direction of the recording medium 1 by the VCM (voice coil motor) 3, or by rotating the rotary roller 5 by the VCM 3.Compared to the normal disk eccentricity, VCM
The movable range of 3 is wide, so if you want to access several to several + tracks, you can do it just by using VCM3. However, in order to access the entire surface of the recording medium 10, it is necessary to move the optical head 6 (see FIG. 2) containing the optical system in the radial direction of the disk using another drive device 7. Moreover, in order to continuously reproduce the friend information from the inside to the outside of the disk, for example, the drive device 3
, 7 must be controlled so that the drive device 3 does not exceed its movable range at all times. Conventionally, for this purpose, a feedback control system using a DC motor was used in the Koei head drive device 7, which tended to make the device complicated and expensive. An optical disk that performs the tracking system using a newly developed and inexpensive device, and is capable of high-speed movement from one head position to another distant position (so-called random access, during which information is not recorded or reproduced). (4) Structure of the Invention The object of the present invention is to provide an optical head which houses an entire optical system for reading or writing information by focusing light on a 9-rotation disk. a drive device having a step motor for moving the optical head in a radial direction on the rotating disk; a detection circuit for detecting a drive current of a tracking control drive device in the optical head; a low-pass filter connected to the output; a first comparator circuit for detecting that the output of the nuclear low-pass filter has exceeded a first reference value; and a first comparator circuit for detecting that the output of the nuclear low-pass filter has exceeded a second reference value. of! Completely equipped with 2 comparator circuits and 1M 1st. This is achieved by providing an optical disk device characterized in that the step motor is controlled by the output of the second comparator circuit.

(5) Embodiment of the Invention According to an embodiment of the present invention, light is focused on information formed in a pit shape on a 9-rotating disk, and the information is read or new pit-shaped information O is written. , a so-called optical disk device includes an optical system head, a drive device powered by a step motor that moves the entire head to a radius above the disk, and enables random access. , a detection circuit that is located in the optical head and detects a drive current of a drive motor (tracking actuator) that is guided by a spring or rubber or the like to correct track deviation due to disk eccentricity and moves a mirror, lens, etc.; a low-pass filter that receives the detection circuit as an input and passes only waves of the same wave number or less, which are sufficiently lower than the rotational speed of the rotating disk; and a first comparator that detects when the output of the filter becomes equal to or less than a first reference value. circuit and a second comparator circuit for detecting that the value has fallen below a second standard value. These comparator circuits determine whether or not the tracking actuator has gone out of the set movable range, and the output thereof operates the drive circuit of the step motor. This will be explained in more detail below with reference to the drawings.

FIG. 3 shows the construction of an optical disk device according to an embodiment of the present invention, and FIG. 3 shows an IFi rotating recording medium (disc) and 20 optical heads.

In this optical head 20, a condensing lens 2 supported by a spring, rubber, etc. 4 is connected to a VCM 3, and a driving circuit 26 moves the lens 2 in the radial direction to perform tracking control. The internal structure of the optical head 20 above may be of the type using the rotating mirror 5 as explained in Figure 1 (6). On the other hand, 12 is a step motor and pulley 17.1
8. The belt 19 converts the rotational force of the motor into linear movement, and moves the optical head 20t in the radial direction of the disk 1. 13
Fi, in the step motor drive circuit, the pulse motor is rotated by the required angle each time one pulse is input to the CW or uccW input, and when the pulse is not needed, it is detented to the current position.

Further, the step angle is determined by the motor, but can be made sufficiently small by using a microstep drive circuit that changes the excitation current in steps.

Next, considering the current I flowing through the VCM 3, ΔX=JXi S inJ(wnt+g i )
(i = 1.2, 3... - here Wn is the disk rotation frequency), so the corresponding current is also I = I + Σl1ain; force coefficient of VCM3) Therefore, the current detection resistor 7 detects the drive current. However, if components exceeding Wn are cut through the entire low-pass filter 8, an output proportional to the average deflection amount X of the spring can be obtained. Therefore, this output is sent to the comparator circuits 9, 10 . If the reference voltage setting circuit 11゜11' is configured and the +n path is passed through, the average deflection of the support spring 4 will be on the 1nner side or 'Fi, outer.
It is possible to construct a circuit that detects when someone is worrying too much. With this output, if the optical head 20 is moved in a direction that offsets the amount of deflection of the feed spring to the output t of the gate circuit 21, 221-open 9 oscillation circuit 14 to the step motor drive circuit 13, the spring will be bent and tracking will be impossible. It will never be. Also.

The optical head 20f is moved regardless of the deflection of the spring to perform random access, and if necessary, the multiplexer 15 is switched by a command from the control circuit 16.
The gate circuits 21 and 22 may be operated by commands from.

1+ The same wave number of the oscillator 14 is shown as an example of the signal waveform at A to F in FIG. Note that the comparator circuits 9 and 10 are respectively.

It is assumed that there is a hysteresis characteristic t4 in which the output is held until the signal B becomes zero.

As described above, according to the present invention, it is possible to provide an apparatus in which a tracking actuator and an optical rad actuator are linked to each other to smoothly input and output information using a pulse motor that can reduce costs. It should be noted that the present invention is not limited to the above-mentioned device having a rotation-straight translation mechanism using the above-mentioned welfare pulley and belt; however, the present invention is not limited to this;
Can also be used with linear step motors

[Brief explanation of drawings]

Figure 1 is a diagram showing an example configuration of a tracking actuator.
FIG. 2 is a diagram showing an example of the configuration of an optical head driving device. FIG. 3 is a diagram showing the configuration of an optical disc apparatus O according to an embodiment of the present invention, FIG. 4 #i, and a diagram showing signal waveforms of various parts in FIG. In the figure, 1#-i disk, 3 a tracking actuator (VCM), 7 a drive current detection resistor, 8 a low-pass filter, 9.10 a comparator [111*
12 is a step motor, 13 is a step motor drive■
bribe. 2(L) View with optical head〇

Claims (1)

[Claims] an optical head housing an optical system for reading or writing information by focusing light on a rotating disk; and a driving device having a step motor for moving the optical head in a radial direction on the rotating disk. A detection circuit for detecting the drive current of the tracking control drive device in the optical head; a low-pass filter connected to the output of the #detection circuit;
#1. Optical disk device 0 characterized in that the step motor is controlled by the output of a second comparator circuit.