JPH04241229A - Optical disk device - Google Patents

Abstract

PURPOSE:To surely perform various kinds of servo control to an actuator and to eliminate the risk of the runaway of the actuator just by providing a limit switch near to the position of the innermost peripheral track of an optical recording medium and further to obtain an effect that the positional accuracy or the limit switch and the accuracy of the limit switch itself need not be so high. CONSTITUTION:When a power source is turned on, an optical pickup 4 moves toward the position PT1 of the innermost peripheral track, and when the limit switch 15 detects that the optical pickup 4 reaches near the position PT1, the optical pickup 4 is a little moved to an outer periphery side where a signal is recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly to an optical disk device provided with a limit switch.

0002

2. Description of the Related Art Some optical disk devices are equipped with a limit switch at a position slightly outside the innermost track position of the optical disk (hereinafter referred to as the innermost track position). be. In this type of optical disc device, at the start of a playback operation, when the optical pickup is moved to the innermost track position of the optical disc and the above-mentioned limit switch detects that it has reached the innermost track position,
There are some systems in which the movement of the optical pickup is stopped and then various servo controls such as focus, tracking, spindle, and thread control are performed. An example of such a conventional technique is disclosed in Japanese Patent Publication No. 1-40425.

0003

In the above-mentioned prior art, the above-mentioned limit switch must always be provided on the outer circumferential side of the optical disk rather than the innermost track position. This is because if a limit switch is installed further inward than the innermost track position of the optical disc, even if you try to apply the various servos mentioned above at the position where the limit switch is turned on, the limit switch will not work properly. Since no pits or grooves constituting servo information are formed further inward than the inner track position,
There was a problem that servo control could not be performed. In this case, servo control of actuators such as spindle motors and threads cannot be performed, so
There was a problem that there was a risk that the actuator would run out of control.

[0004] For this reason, the limit switch for detecting the innermost circumference is required to have high positional accuracy, and the limit switch itself has to be highly accurate and therefore expensive. Furthermore, since optical disks generally have eccentricity, there is a problem in that it is difficult to accurately detect the innermost circumference.

[0005] Accordingly, an object of the present invention is to provide an optical disk device that can reliably apply servo to an actuator without using a limit switch that is not highly accurate and without having to perform positioning with such high precision.

[0006]

[Means for Solving the Problems] The present invention provides an optical pickup for reproducing at least a signal from an optical recording medium provided with an area in which signals are recorded in the form of concentric circles or spiral tracks; In an optical disk device that is provided with means for identifying the boundary between an area where a signal is recorded and an area where no signal is recorded on the medium, the optical pickup is After detecting that the optical pickup is located near the boundary of the area, the optical pickup is moved in the direction of the area where the signal is recorded.

[0007]

[Operation] When the power is turned on, the optical pickup is moved to the vicinity of the boundary between the area where signals are recorded and the area where no signals are recorded on the optical recording medium. When the optical pickup reaches the vicinity of the above-mentioned boundary, it is detected by, for example, a limit switch. When it is detected that the optical pickup has reached the vicinity of the boundary, the optical pickup is slightly moved in the direction of the area where the signal is recorded.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In the configuration shown in FIG. 1, a focus error signal FER, a tracking error signal TER, and a reproduction signal are output from an optical pickup 4 that forms a light spot 3 on a surface 2 of an optical disk 1, respectively. This optical pickup 4 has a laser light source, a collimator lens, a beam splitter, an objective lens, various optical sensors, etc. inside the parts (not shown). It is movable by a guide shaft (not shown).

The above-mentioned focus error signal FER is supplied to the phase compensation circuit 6 and after phase compensation is supplied to the focus servo circuit 8. The focus servo circuit 8 forms a control signal based on the phase-compensated focus error signal FER, supplies this control signal to the optical pickup 4, and controls the focus servo in the direction of arrow F in FIG. I do.

The above-mentioned tracking error signal TER is supplied to the phase compensation circuit 7 and after phase compensation is supplied to the tracking servo circuit 9. In addition, the phase compensation circuit 7
From there, a sled error signal SER is formed based on the low-frequency component of the above-mentioned tracking error signal TER, and is supplied to the sled drive control circuit 11 .

The tracking servo circuit 9 forms a control signal based on the phase-compensated tracking error signal TER, supplies this control signal to the optical pickup 4, and controls the tracking servo in the direction of arrow T in FIG. I do. The thread drive control circuit 11 generates a drive control signal SM shown in FIG. 3 based on the thread error signal SER.
0 and supplies this drive control signal SMO to the drive circuit 12. The drive circuit 12 controls the movement of the optical pickup 4 in the radial direction of the optical disc 1, that is, in the direction of arrow T in FIG.

The movement of the optical pickup 4 in the radial direction is controlled not only by the thread error signal SER described above but also by the control of the CPU 16. This is done, for example, when the optical pickup 4 is moved to a predetermined position at the start of a reproduction operation.

The above-mentioned reproduction signal is then supplied to the spindle servo circuit 13. Spindle servo circuit 13
Now, in a state where tracking is achieved, a synchronization signal is extracted from the above-mentioned reproduced signal, a control signal is formed based on this synchronization signal, and this control signal is supplied to the spindle motor 14 to perform spindle servo. .

Innermost track position PT1 of optical disk 1
A limit switch 15 is provided near a position corresponding to . , an arrival signal SPT1 indicating that the optical pickup 4 has reached the vicinity of the innermost track position PT1 is supplied to the CPU 16. C
When the PU 16 is supplied with the above-mentioned contact signal SPT1, it supplies a control signal Sc to the sled drive control circuit 11 in order to drive and control the optical pickup 4.

The operation of this circuit will be explained below with reference to the flowchart of FIG. When the power is turned on, CPU1
A control signal Sc is supplied from 6 to the thread drive control circuit 11. The thread drive control circuit 11 generates the drive control signal SMO shown in FIG. 3 based on the above-mentioned control signal Sc. This drive control signal SMO has the illustrated polarity, for example, negative polarity, during the period t1 to t2 shown in FIG. applied to the motor. As a result, the optical pickup 4 is moved to the inner circumferential side of the optical disc 1 (step 101).

When the optical pickup 4 reaches the vicinity of the innermost track position PT1 and contacts the limit switch 15 during the period t2, the limit switch 15 supplies the arrival signal SPT1 to the CPU 16, and under the control of the CPU 16, the The supply of the drive control signal SMO is stopped over the period t2 to t3 shown in FIG. As a result, the movement of the optical pickup 4 is stopped (step 102
).

In the next step 103, under the control of the CPU 16 over the period t3 to t4 shown in FIG.
Positive polarity drive control signal S from the thread drive control circuit 11
MO is supplied. As a result, the optical pickup 4
is moved to the outer circumferential side of the optical disk 1. At this time, the CPU
The software timer starts at step 16 (step 10).
4). In this timer, the period t3 to t4 shown in FIG.
A predetermined period of time, for example, 50 ms, is measured, and during this period, the optical pickup 4 is moved toward the outer circumferential side of the optical disk 1. This is the optical pickup 4,
This is because if it is moved toward the outer circumference of the optical disc 1 for this amount of time, it will definitely reach the pit or groove of the optical disc 1.

The above-mentioned predetermined time is the period t4 shown in FIG.
When the movement is completed, the movement of the optical pickup 4 is stopped (step 106), and the optical disk 1 is moved at a position PL1, which is a distance L1 away from the innermost track position PT1, during the period t4 to t5 shown in FIG. It's stopped. and,
After detecting the pit or groove at this position PL1, various servo controls such as focus servo, tracking servo, thread servo, etc. are performed from period t5 shown in FIG. 3 (step 107). Note that in FIG. 1, AR indicates an area on the optical disc 1 where signals are recorded.

According to this embodiment, when the power is turned on, the optical pickup 4 moves toward the innermost track position PT1, and the limit switch 15 causes the optical pickup 4 to reach near the innermost track position PT1. When this is detected, the optical pickup 4 is moved slightly to the outer circumference side where the signal is recorded, and then various servos are applied, so that the limit switch 15 is moved to the innermost circumference of the optical disc 1 as in the conventional case. Even if the servo is not provided on the outer circumferential side of the track position PT1, as long as it is provided near the innermost track position PT1 of the optical disk 1, the servo can be reliably provided to actuators such as the spindle motor 14 and the drive circuit 12. This eliminates the risk of the actuator running out of control. Furthermore, the position accuracy of the limit switch 15 and the accuracy of the limit switch 15 itself do not need to be so high, and inexpensive ones can be used.

In this embodiment, when the power is turned on, the optical pickup 4 moves to the innermost track position PT1, and moves for a predetermined time from the innermost track position PT1 toward the outer track where the signal is recorded. However, the invention is not limited to this. For example, if the starting end of the recorded signal is on the outermost track, the optical pickup 4 may be moved to the outermost track position when the power is turned on. However, it may be arranged to move for a predetermined period of time from the outermost track position toward the inner circumference where signals are recorded. Further, the polarity of the drive control signal SMO in FIG. 3 is not limited to that shown in the figure, but can also be converted into a relative voltage level and used.

[0021]

According to the optical disk device according to the present invention, when the power is turned on, the optical pickup is located near the boundary between the area where the signal is recorded and the area where the signal is not recorded on the optical recording medium. When the optical pickup is moved and the limit switch detects that it has reached the vicinity of the boundary, the optical pickup is moved slightly in the direction of the area where the signal is recorded. Even if it is not provided on the outer side of the innermost track position of the optical recording medium, as long as it is provided near the innermost track position of the optical recording medium, servo control can be reliably performed on various actuators. This has the effect of eliminating the risk of the actuator running out of control. Furthermore, the positional accuracy of the limit switch and the accuracy of the limit switch itself do not need to be so high, and there is an effect that an inexpensive one can be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an optical disk device according to the present invention.

FIG. 2 is a flowchart showing a procedure for moving an optical pickup when power is turned on.

FIG. 3 is a waveform diagram showing a drive control signal SMO.

[Explanation of symbols]

1. Optical disk 4 Optical pickup 15 Limit switch AR area PT1 Innermost track position T Radial direction

Claims (1)

[Claims] 1. An optical pickup for reproducing at least a signal from an optical recording medium provided with an area in which the signal is recorded in the form of concentric circles or spiral tracks;
In an optical disk device provided with a means for identifying a boundary between an area where a signal is recorded and an area where a signal is not recorded of the optical recording medium, the means for identifying the boundary. After it is detected that the optical pickup is located near the boundary of the area,
An optical disc device characterized in that an optical pickup is moved in the direction of an area where a signal is recorded.