JPH038127A - Seek system for optical disk recording/reproducing device - Google Patents

Abstract

PURPOSE:To reduce the power consumption of a driving circuit, and also, to exactly execute the seek operation by supplying a seek driving signal by a PWM signal, and also, stopping the supply of the PWM signal, when an actuator passes through an address area. CONSTITUTION:When a seek command signal ESK is inputted, a signal obtained by bringing a seek signal from a seek control part 6 to PWM modulation is supplied to a driving circuit 3 through an AND gate 8. The driving circuit 3 becomes an ON/OFF control, and electric power consumed by the driving circuit 3 is extremely small. On the other hand, when a movement of an actuator falls, and read-out of data becomes possible, an address signal PAD is outputted from a CPU 5. By applying this signal to the gate 8, it is prevented that a PWM signal PWM is supplied to the driving circuit 3 as a seek signal, when a beam spot is crossing an address area even in the course of seek.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a seek method for an optical disc recording/reproducing device, and particularly relates to a seek method useful when moving an actuator to seek a target track. .

[Summary of the Invention] The seek method of the optical disc recording/reproducing apparatus of the present invention normally supplies a tracking error signal to its tracking servo circuit, and when seeking a target track, a seek drive is used to rapidly control the movement of the optical head. PW as a signal
M (Pulse Width Modulation
) signal, it is possible to reduce heat generation in the drive stage that drives the tracking actuator and improve power efficiency.

Also, when the beam spot passes through the address area,
Since it is configured to stop supplying PWM signals,
It is possible to read the address data and perform seek operations with higher precision.

[Prior Art] In an optical disc recording/reproducing device, when reading data recorded on an optical disc or writing data onto an optical disc, a seek or track jump is performed to move an optical head to a desired track position. It will be necessary to do so.

In such a seek device, -1i1R stores the current playback/
Alternatively, the control unit (CPU) calculates the number of tracks from the track being recorded to the target track, and uses that number of tracks as the target value to form a seek drive signal to move the optical head as quickly as possible. The signal is supplied to the tracking actuator of the optical head.

However, in order to move the optical head to the target track in a short time, a large-amplitude drive voltage (current) is required, and it is also necessary to control the speed at which the optical head can turn on tracking again just before the target track.
It will also be necessary to

Therefore, the applicant has previously proposed a seek method that can easily achieve a tracking-on state on the target track by detecting the moving speed of the tracking actuator during the seek operation and feeding back this moving speed. .

FIG. 6 shows a block diagram of such a seek method.

In this figure, the control circuit 11. The counter circuit 12° D/A converter 13 forms a main target setting unit 10 that generates a target value signal for moving the coarse actuator 18 to a desired track when seeking, and the inverting circuit 14 forms a switch circuit depending on the seek direction. 15 is switched, it supplies an inverted output.

During the seek operation, the b contact of SW is connected, and the output of the adder circuit 16 is a drive signal to which a speed servo is applied based on the speed signal output from the speed sensor circuit 19 via the drive circuit 17. and is supplied to the coarse actuator 18. Therefore, when the target value signal is accurate and the speed sensor circuit 19 is outputting speed information with high accuracy, this circuit allows the coarse actuator 18 to jump to the target track.

Further, the seek device shown in this prior art includes a seek control section 20. and a secondary tank setting section 30 are provided.

The address data and control signal of the optical disc are input to the seek control unit 20, and the address data A at the start of seek is inputted to the seek control unit 20.
p and target track address data A. is formed.

Also, during the seek operation, the address data reproduction/reading mode is set, and for example, when the seek speed decreases near the target track and the address data is read out, a signal S is sent to select the C contact of the switch S W +. , is output.

The sub-target setting section 30 includes at least a track number detection section 30A that detects the number of tracks up to the target track, and a speed detection section 30B that detects the moving speed of the coarse actuator 18 based on the read address data. There is.

In this prior art, a conventional seek device is provided with a sub-target setting section 30 that operates based on address data, and the output of this sub-target setting section 30 indicates that it is possible to read an address. Since the signal Sl from the seek control unit 20 is supplied to the coarse actuator 18, a more accurate seek operation can be performed.

[Problems to be Solved by the Invention] Incidentally, in the above-described seek device, since the drive circuit 17 is driven by an analog signal, when the device is miniaturized, the amount of heat generated during seeking is reduced. There was a problem in that the number increased.

Therefore, it is conceivable to convert the drive signal supplied to the drive circuit 17 into, for example, a pulse width modulated signal and drive the actuator using the power/off control section. The recording/reproduction signal is contaminated by the spike voltage caused by the
There is a drawback that it becomes difficult to import address data into the sub-target setting section 30 during seek.

Means for Solving Problem E] The present invention has been made in view of such problems, and the servo signal during normal recording and reproduction is supplied to the drive circuit in the form of an analog signal, and the drive signal during seek operation is is PW
At the same time as supplying the M-modulated pulse signal to the drive circuit, the timing at which the beam spot crosses the address area of the optical disk during seek is detected, and the PWM drive signal is not supplied during this period. This is what I did.

[Effect 1] Since the level of the tracking error signal supplied during normal recording and reproduction is extremely low in the tracking state, power consumption that would cause the drive circuit to generate heat is not generated.

Also, the seek drive signal supplied during the seek operation is P
Since it is WM modulated, the drive stage of the actuator is controlled in an on-state manner, and power consumption can be reduced.

[Embodiment] FIG. 1 shows a basic block diagram of the seek method of the present invention, in which 1 is a tracking error signal phase compensation circuit, 2 is a servo/seek operation changeover switch,
3 is an actuator consisting of a power amplifier, etc.
The drive circuit for linear motor 4 is shown.

5 is a CPU that controls the optical disc recording and reproducing device
The CPU 5 is capable of reading out the optical disc's trunk number, address, etc. from at least the reflected light of the laser beam irradiated onto the optical disc.

Reference numeral 6 denotes a seek control unit that outputs an optimal seek drive signal based on the seek target value and the moving speed of the actuator when performing a seek operation, and for example, the main target setting unit IO as shown in FIG. A functional circuit corresponding to the sub-target setting section 30 is provided.

7 is P for pulse width modulating the output level of the seek control section 6.
A WM signal conversion section is shown, and the output signal of this conversion section is supplied to the other input of the changeover switch 2 via an AND gate 8.

The other input of the AND gate 8 is supplied from the CPU 5 with an address detection signal PAo that becomes a low level in the address area of the rotating optical disk. Gate 8 closes (°L” level).

As shown in FIG. 2, the address detection signal PAD is a wind pulse that detects the address area AD recorded at the beginning of each sector of the track T of the optical disc, and includes:
This wind pulse is formed based on the sector clock psc that detected the sector mark SM located at the beginning of the address data.

DA of track T indicates an area where data is written.

As described above, in the seek method of the optical disc recording/reproducing apparatus of the present invention, during normal recording/reproducing, the selector switch 2 is
A contact point is selected and a tracking error signal is supplied to a drive circuit 3 via a phase compensation circuit 1. When the seek command signal E sx is input, the changeover switch 2 selects the b contact, and a signal obtained by PWM modulating the seek signal output from the seek control unit 6 is supplied to the drive circuit 3 via the AND gate 8. be done.

Since the PWM-modulated seek drive signal pwi+ has a digital waveform as shown in FIG. 3, the drive circuit 3 performs so-called on/off control, and the power consumed by the power transistor of the drive circuit is extremely small.

However, when the actuator 4 is subjected to on/off control, a spike current is generated in the drive coil of the actuator, and this spike current becomes noise and deteriorates the data being read. Therefore, even when the seek speed is low, it becomes difficult to read address data, and the accuracy of the seek operation decreases.

Therefore, in the case of the present invention, especially when the moving speed of the actuator decreases and data reading becomes possible, the CPU 5 outputs the address detection signal PAD, and as shown in FIG. By applying it to the gate 8, the PWM signal pvM is prevented from being supplied to the drive circuit 3 as a seek signal when the beam spot crosses the address area AD even during seek. Therefore, even during seek, the seek control unit 6, in particular,
It becomes possible to capture address data when the speed of the actuator 4 decreases as the speed of the actuator 4 approaches the target track, and seek accuracy can be increased.

Note that the address detection signal PAD is based on the actual address area A.
It is preferable that the width of D is wider than the width of D by a time T<L, so that there is no influence of spike noise generated by the electric energy stored in the drive coil at the moment when the PWM signal is absent.

FIG. 4 shows a specific circuit example of the drive circuit of the actuator 4, where L is the drive coil of the linear motor, Q,
, Q2. Q3. Q4 is a complementary-connected push-pull drive transistor, and D is a spike prevention diode.

02,0□ indicates a differential amplifier provided to apply a voltage that is 1/2 of the power supply voltage V when driving the drive coil L with a single power supply so that the transistor becomes push-pull. .

Further, S, , S2 indicate changeover switches for switching between servo/seek operations, and when a seek command signal E sx is input, a contact point S is selected.

A1. At represents an AND circuit into which the jump direction signal F/R, the aforementioned PWM signal and address detection signal are input, and IN represents an inverter.

In this drive circuit, the positive phase input terminal of the differential amplifier 02 has a potential divided to 1/2V by the resistors R, , R2, and when the changeover switches S, , S2 are in the a contact is controlled so that both ends of the drive coil L are 1/2v.

However, the differential amplifier 0. When one terminal of the drive coil L increases by ΔV due to the tracking error signal E supplied from the positive phase input terminal of the drive coil L, the other terminal of the drive coil L decreases by Δ■, and the tracking error signal E It is driven by a current that is positive or negative depending on the level of .

Next, the seek command signal E sx is applied to the changeover switches S, , S
, the equivalent circuit is shown in Figure 5(a).
It becomes as shown in .

According to this equivalent circuit, when the jump direction signal F/R is positive, the output of the AND circuit A2 becomes the °L" level, as shown in FIG.
2 are alternately opened and closed by the AND output of the AND circuit A1, and the drive signal is interrupted by the PWM signal as shown by the dotted line.

In this case, as shown in FIG. 3, when the address detection signal PAD becomes low level, the transistor Q2 is turned on and the transistor Q1 is turned off, so that the drive coil becomes a short circuit as shown by the dashed line. During this time, PWM
No signal provided.

Therefore, when the beam spot approaches the address area of the track during seek, the on/off control is interrupted and the drive coil L is short-circuited, thereby reliably preventing the generation of spike noise. can be performed accurately, and as a result, seek accuracy can be increased.

Note that the jump direction is reversed and the negative signal is output to AND circuit A.
, the transistor Q2 is turned on and the transistor Q4 is turned off, as shown in FIG. 5(C).

Therefore, the drive signal in the direction shown by the dotted line is intermittent in the drive coil L by the PWM signal, and the seek speed is controlled.
When Ao becomes low level, transistor Q4 turns on and transistor Q3 turns on (low level), so the on/off control is interrupted in the same way as described above.

[Effects of the Invention] As explained above, the seek method of the optical disc recording/reproducing apparatus of the present invention is driven by a tracking error signal, which is an analog signal, from the drive circuit in a normal servo state, and during a seek operation, the drive circuit is driven by a tracking error signal, which is an analog signal. to PWM
Since the modulated digital signal is supplied as the seek drive signal, the power consumption of the drive circuit can be constantly reduced and miniaturization can be easily achieved.

Furthermore, even during a seek operation, the PWM signal is controlled to be disabled when the beam spot passes through the address area of the track, so it is possible to read the track address of the optical disk even during the seek operation, making it possible to This has the advantage that accurate seek operations can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the seek method of the present invention, Fig. 2 is an explanatory diagram of the track address area and detection signal, Fig. 3 is a waveform diagram of the PWM signal and address detection signal, and Fig. 4 is a diagram of the drive stage. Drive circuit diagrams showing specific examples, FIGS. 5(a)(b)
)(c) is an equivalent circuit diagram during a seek operation, and FIG. 6 is a block diagram showing a prior art of a seek device. In the figure, 1 is a phase compensation circuit, 2 is a changeover switch, 3 is a drive circuit, 4 is an actuator, 5 is a CPU 6 is a seek control section, and A is a push-pull conversion section.

Claims (2)

[Claims] (1) In a seek method of an optical disc recording/reproducing device, the tracking actuator is equipped with a switching means for selecting either a tracking error signal or a seek drive signal, and a drive circuit that amplifies the output of the switching means and supplies it to a tracking actuator. The error signal is supplied as an analog signal, the seek drive signal is supplied as a PWM signal, and the supply of the PWM signal is stopped when the actuator passes through an address area of the optical disk. A seek method for an optical disc recording/playback device characterized by the following. (2) A seek method for an optical disc recording/reproducing apparatus according to claim (1), wherein the seek drive signal is controlled based on track address information during seek.