JPH0748260B2 - Track jump device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track jump used in an optical disk device or the like.

2. Description of the Related Art Generally, an optical disk device or the like uses a semiconductor laser that outputs a beam, an objective lens that collects the beam and irradiates it onto a recording medium such as an optical disk, or a beam reflected from the recording medium through an objective lens. It has an optical pickup provided with an element and the like for receiving light.

The objective lens of this optical pickup can be minutely moved in the radial direction of the recording medium so that the beam follows the tracks of the recording medium (tracking), or seeks closely between tracks and jumps.

FIG. 2 shows a track jump device in a conventional optical disk device.

In FIG. 2, a sinusoidal tracking error signal is obtained by the difference between the target displacement and the actual displacement of the objective lens 25, and this tracking error signal is converted by the binarization circuit 28 as shown in the lower part of FIG. After being binarized, the control logic circuit 29 turns off the switch 21 and turns on the switch 22 by the rising edge of the binarized signal and the jump command from the drive controller (DRC) 27 to perform track jump control (speed control), Then, at the next rising edge of the binarized signal, the switch 21 is turned on and the switch 22 is turned off to perform the track following control.

In the above configuration, when controlling the beam to follow the track of the recording medium, the control logic circuit
The switch 21 is on and the switch 22 is off under the control of 29. In this case, the tracking error signal is stabilized by the phase compensation circuit 23 and input to the drive circuit 24 via the switch 21.

The drive circuit 24 finely moves the objective lens in the radial direction of the recording medium so that the tracking error signal becomes “0”, and as a result, controls the beam to follow the track of the recording medium.

On the other hand, when controlling the beam to jump between tracks on the recording medium, the switch 21 is off and the switch 22 is on under the control of the control logic circuit 29.
In this case, the tracking error signal is the speed detection circuit.
An actual relative speed signal with respect to the track of the objective lens 25 is obtained by being differentiated by 26, and the difference between the target speed signal and this actual speed signal is input to the drive circuit 24 via the switch 22.

The drive circuit 24 finely moves the objective lens in the radial direction of the recording medium so that this signal becomes “0”, and as a result, the beam is controlled so as to jump between the tracks of the recording medium.

Therefore, in the above-mentioned conventional example, the track tracking control is switched to the track jump control (speed control) by the rising of the binarized signal of the tracking error signal and the jump command, and the beam reaches the target track at the next rising of the binarized signal. It is possible to switch from the track jump control to the track follow-up control by detecting the fact.

Problems to be Solved by the Invention However, in the above conventional track jump device,
Since the track jump control is switched to the track follow-up control by the second rise of the binarized signal of the tracking error signal, the objective lens is decelerated by disturbance or the like during the track jump control, and the relative speed of the objective lens to the track of the target track. When it becomes "0" just before,
There is a problem that the second rising edge of the binarized signal is not detected and the objective lens moves in the direction opposite to the direction of the target track, so that the beam takes a long time to access the target track.

In view of the above problems, the present invention is capable of reliably switching from track jump control to track following control even when the second rising edge of the binarized signal of the tracking error signal is not detected during track jump control. The purpose is to provide.

Means for Solving the Problems In order to solve the above problems, the present invention is provided with means for measuring a predetermined time when a jump command is input, the jump command is input, and a binarized signal rises. Sometimes switch from track following control to track jump control,
When the next binarized signal rises or when the time measuring means measures a predetermined time, the track jump control is switched to the track following control.

Operation According to the present invention, the objective lens is decelerated due to disturbance or the like during the track jump control, the relative speed of the objective lens with respect to the track becomes "0" immediately before the target track, and the second time of the binarized signal. Even when the rising edge is not detected, the track jump control can be switched to the track following control after the elapse of a predetermined time by the time counting means after the jump command.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First
FIG. 1 is a block diagram showing an embodiment of a track jump device according to the present invention.

In FIG. 1, 13 is a phase compensation circuit that stabilizes a sinusoidal tracking error signal due to the difference between the target displacement of the objective lens 15 and the actual displacement, and 11 is a recording medium whose beam is recorded by a control logic circuit 19. Switch that turns on when controlling to follow the track, 14
Is a drive circuit for driving the objective lens so that the input signal becomes “0”.

16 differentiates the tracking error signal to obtain the objective lens 15
The speed detection circuit for obtaining an actual relative speed signal to the tracks of the switch 12 is a switch which is turned on when the beam is controlled to jump between the tracks of the recording medium by the control of the control logic circuit 19. Yes,
In this case, the difference between the target speed signal and the actual speed signal is input to the drive circuit 14 via the switch 12.

Reference numeral 17 is a drive controller (DRC) that outputs a jump command for switching from track following control to track jump control, 18 is a binarizing circuit that binarizes a tracking error signal, and 19 is a switch 11 as will be described later. ,
A control logic circuit for controlling 12 and 20 are timers for measuring a predetermined time (for example, 1 msec) within a time range in which the beam can reach the target track.

Next, the operation of the embodiment having the above configuration will be described.

In FIG. 1, when controlling so that the normal beam follows the track of the recording medium, the control logic 19
The switch 11 is turned on and the switch 12 is turned off by the control of 1. In this case, the tracking error signal is stabilized by the phase compensation circuit 13, and the drive circuit is stabilized via the switch 11.
Enter in 14.

Therefore, the drive circuit 14 slightly moves the objective lens 14 in the radial direction of the recording medium so that the tracking error signal becomes "0", and as a result, the beam is controlled to follow the track of the recording medium.

Here, when the drive controller 17 outputs a jump command to the control logic circuit 19 and starts the timer 20, the control logic circuit 19 turns off the switch 11 by the rising of the binarization signal from the binarization circuit 18, and switches it. Turn on 12 to switch from track following control to track jump control.

Therefore, the tracking error signal is transmitted to the speed detection circuit 16
Is differentiated to obtain an actual speed signal, and the difference between the target speed signal and this actual speed signal is input to the drive circuit 14 via the switch 12, and the drive circuit 14 sets this signal to "0". Thus, the objective lens 15 is slightly moved in the radial direction of the recording medium, and as a result, the beam is controlled so as to jump between the tracks of the recording medium.

Next, the controller logic circuit 19 converts the binarization circuit 18 into
When the next rising edge of the binarized signal from 1 is input, or when the time-up signal of the timer 20 is input, the switch 11 is turned on and the switch 12 is turned off to switch the track jump control to the track following control.

Therefore, even if the objective lens 15 decelerates due to disturbance or the like during the track jump control and the relative speed of the objective lens 15 to the track becomes "0" immediately before the target track, the track jump control is reliably switched to the track following control. , The beam can access the target track.

EFFECTS OF THE INVENTION As described above, the present invention is provided with means for timing a predetermined time when a jump command is input, and when the jump command is input and the binarized signal rises, the track tracking control is started. Switch to jump control, then
Since the track jump control is switched to the track following control when the value-converted signal rises or when the time measuring means measures a predetermined time, the objective lens is decelerated due to disturbance or the like during the track jump control, and the objective lens is decelerated. Even if the relative speed with respect to the track becomes "0" immediately before the target track and the second rising edge of the binarized signal is not detected, the track jump control can be reliably switched to the track following control.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a track jump device according to the present invention, and FIG. 2 is a block diagram showing a conventional track jump device. 11, 12 …… Switch, 13 …… Phase compensation circuit, 14 …… Drive circuit, 15 …… Objective lens, 16 …… Speed detection circuit, 17 ……
Drive controller, 18 ... Binarization circuit, 19 ... Control logic circuit, 20 ... Timer.

Claims (1)

[Claims] 1. A means for driving an objective lens so that the beam follows a track of a recording medium by a tracking error signal, and driving the objective lens so that the beam jumps between tracks of the recording medium by a velocity signal. And means for binarizing the tracking error signal, means for timing a predetermined time when a jump command is input, and the speed signal when the jump command is input and the binary signal rises. Switch to input to the driving means, and then when the next binarized signal that is emitted when the beam reaches the target track rises, or when the time measuring means measures the predetermined time. And a means for switching so that the tracking error signal is input to the driving means. Track jump apparatus characterized by time said beam is within a time range that can reach the target track.