JPS6224442A - Tracking lead-in device - Google Patents

Abstract

PURPOSE:To properly generate a lock-in signal irrespective of the type of disk by generating a timing signal locking in a tracking servo loop with the use of an RF signal if it exists and a signal corresponding to an average light receiving amount if the RF signal does not exist. CONSTITUTION:When the RF signal is not detected, a detecting means 22 switches a switch 23 to the side of a binarizing circuit 7. The signal, whose DC fluctuating component is removed through a liminous energy detecting means 6 and a bypass filter 21 and which corresponds to the average light receiving amount, is binarized by the binarizing circuit 7, and is inputted to the data terminal of a latch circuit 5 through the switch 23. When the detecting means 22 detects the RF signal, the switch 23 is switched to the side of a binarizing circuit 11. Accordingly an envelope detecting means 10 detects the envelope signal of the RF signal, and a signal obtained by binarizing the envelope signal by the circuit 11 is supplied to the latch circuit 5 through the switch 23. Thus a proper lock-in signal can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an apparatus for recording and reproducing information by irradiating light such as a laser beam onto a disk, in which the pink-up is positioned at a predetermined position relative to the track on the disk. 1 - A racking retraction device that generates a timing signal that locks in a tracking servo loop at a certain time.

[Summary of the invention]

The present invention provides (1) a racking pull-in device including: a pickup that irradiates light onto a disk to record or reproduce information; and a first device that detects a signal corresponding to the average received amount of reflected light from the disk from an output signal of the pickup. a detection means, and a second detecting means for detecting an RF multiplied signal envelope signal of information recorded on the disk from the output signal of the pickup.
, a third detection means for detecting the presence or absence of the RF multiplied signal, a tracking error generation circuit for generating a tracking error signal from the output of the pickup (FI), and a tracking error generation circuit for generating a tracking error signal from the pickup output (FI); generates a timing signal for locking in the tracking servo loop from the RF multiplied signal envelope signal and the tracking error signal, or from the signal corresponding to the average amount of received light and the tracking error signal when the third detection means does not detect the RF signal. The tracking servo loop is locked in by using the RF multiplied signal when the RF multiplied signal exists, and by using the signal corresponding to the average amount of received light when the RF signal does not exist. By generating a timing signal, it is possible to accurately generate a lock-in signal regardless of the type of disc.

[Conventional technology]

FIG. 4 is a block diagram of a conventional tracking pull-in device. In the figure, 1 is a pickup that irradiates light such as a laser beam emitted from a semiconductor laser onto a disk, receives reflected light from the disk, and records and reproduces information; 2;
is a tracking error generation circuit that generates a tracking error signal outputted from the pickup 1 (from the number a).The tracking error signal generated by the tracking error generation circuit 2 is input to the binarization circuit 3, and is converted to a predetermined base. tG1!G1 (for example, O volts) and is converted into a high-level and low-level signal (binarized signal) (waveform-shaped) and supplied to the edge pulse generation circuit 4.The edge pulse generation circuit 4 It detects the rising edge and falling edge of the value signal, generates an edge pulse in synchronization with the detected edge, and outputs it to the clock terminal of the latch circuit 5. 6 is a light amount detection means, and from the output of the pickup 1, A signal corresponding to the average amount of received light reflected from the disk is extracted.The output of the light amount detection means 6 is input to a binarization circuit 7, where it is binarized and supplied to an OR circuit 8.The pickup 1 outputs The reproduced signal is amplified by an amplifier circuit 9, and its envelope is detected by an envelope detection means 10.This envelope signal is binarized by a binarization circuit 11, and is supplied to an OR circuit 8. There is.

The output of the OR circuit 8 is input to the data terminal of the latch circuit 5.

The effect will now be explained. The tracking error signal (FIG. 5(a)) generated from the output signal of the pickup 1 by the tracking error generation circuit 2 is compared with a reference potential of 0 volt by the binarization circuit 3, and is binarized (Fig. 5(a)). Figure 5(d)).

This binarized signal is input to the edge pulse generation circuit 4, which generates edge pulses synchronized with the timing of its rising edge and falling edge (Fig. 5 (h)).
, is supplied to the clock terminal of the latch circuit 5. On the other hand, at the data terminal of the latch circuit 5, a signal corresponding to the average amount of received light generated from the output signal of the pickup 1 by the light amount detection means 6 (see FIG.
It is converted into a value (FIG. 5(e)) and is supplied via the OR circuit 8 (FIG. 5(g)).

For example, when the pickup 1 moves from the outer circumference to the inner circumference of the disk and crosses a track on which no information is recorded, the binary signal of the signal corresponding to the average amount of received light is the timing of the rising edge of the tracking error signal. It becomes a low level at the timing of the falling edge, and becomes a high level at the timing of the falling edge (FIG. 5(i)).

On the other hand, when the transverse direction is reversed from the inner circumferential direction to the outer circumferential direction, the relative phase relationship between the tracking error signal and the signal corresponding to the average amount of received light changes by 180 degrees. As a result, the binary signal corresponding to the average amount of received light is at a high level at the timing of the rising edge of the tracking error signal.
Moreover, it becomes a low level at the timing of a falling edge (FIG. 5(j)).

On the other hand, when crossing the 1-rack where information is recorded, the amplifier circuit 9 outputs an RF multiplied signal (FIG. 5(C)), and the envelope detection means 10 detects the envelope. This envelope signal is binarized by the binarization circuit 11 (
(FIG. 5(f)), and is input to the data terminal 1 of the latch circuit 5 via the OR circuit 8 (FIG. 5(g)). That is, R
When F-fold signal exists, binarization time i? 811 outputs a high-level on-track signal, and when the RF multiplied signal is not present, the binarization circuit 7 outputs each on-track signal, so the OR circuit 8 outputs the logical sum signal (FIG. 5 (g)).
This means that you are getting . When the high level section of the signal output by the latch circuit 5 crosses from the outer circumference to the inner circumference, it corresponds to a negative section of the tracking error signal, and when it crosses from the inner circumference to the outer circumference, it corresponds to a tracking error signal. It corresponds to the positive section of the signal. Therefore, by turning on the tracking servo loop in response to this signal, it is possible to reduce the relative speed between the disk and the pickup and achieve lock-in. Since the principle and the like are described in the specification of JP-A-57-120276, etc., a detailed explanation thereof will be omitted.

[Problem that the invention seeks to solve]

By the way, the change in the signal corresponding to the average amount of light received when it crosses the track is small compared to its absolute DC level.
This is on the same level as the DC level fluctuation that occurs when there is a difference in local reflectance of the disk. Therefore, for example, when the binarization circuit 7 binarizes a signal corresponding to the average amount of received light using a fixed level as a reference, there may be portions that cannot be binarized due to fluctuations in the DC level, as shown in FIG. In order to prevent this, it is conceivable to extract a signal corresponding to the average amount of received light through an AC coupling via a capacitor or the like so as to remove the DC fluctuation component. In this case, as in the example mentioned above, in a disc where the signal corresponding to the average amount of light received in the information recording section does not change, 2
Since the digitization circuit 7 does not output the binarization A3, there is no gap. However, for example, in the case of a disc in which the effect of increasing the reflectance in the recording section exceeds the effect of decreasing it due to diffraction, the on-track and inter-track phases of the signal corresponding to the average amount of received light obtained by AC coupling will be The information recording area and the unrecorded area are reversed (FIG. 7(a)). Therefore, the signal corresponding to the average amount of received light (FIG. 7(a)) is binarized (FIG. 7(C)), and the RF multiplied signal outputted by the amplifier circuit 9 (FIG. 7(b)). Signal that binarized the envelope (
An on-track signal cannot be generated from the logical sum signal (FIG. 7(e)) with FIG. 7(d)). As a result, conventional devices such as those described above have the disadvantage of not being able to generate such a disk lock-in signal.

[Means for solving problems]

FIG. 1 shows a block diagram of the tracking pull-in device of the present invention, and parts corresponding to those in FIG. 4 are given the same reference numerals, and detailed description thereof will be omitted. The output signal of the light amount detection means 6 is supplied to the binarization circuit 7 via a bypass filter 21 that blocks DC fluctuation components. Further, the output of the amplifier circuit 9 is input to the detection means 22 (of course, the output of the envelope detection means 10 may also be used), and the presence or absence of the RF multiplied signal is detected. 23 is a switch which is switched by the output of the detection means 22, and selects the output signal of the binarization circuit 11 when the RF multiplied signal is detected, and selects the output signal of the binarization circuit vI7 when the RF multiplied signal is not detected. It is selectively outputted and supplied to the data terminal of the latch circuit 5. The other configurations are the same as in FIG. 4.

[Effect]

The effect will now be explained. The reproduced signal from the pickup 1 is amplified by the amplifier circuit 9 and inputted to the envelope detection means 10 and the detection means 22 for detecting the presence or absence of the RF multiplied signal.

Assuming that the pickup 1 is now being moved from the outer circumference to the inner circumference of the disk and is crossing a track (pre-group) on which no information is recorded, the RF multiplied signal will not be detected, so the detection means 22 will set the switch 23 to 2. A low level signal to be switched to the value converting circuit 7 side is output (FIG. 2(e)). Therefore, in this case, the signal (FIG. 2(a)) corresponding to the average received light amount output from the light amount detection means 6 and from which DC fluctuation components have been removed by the bypass filter 21 is
The signal is binarized by the binarization circuit 7 (FIG. 2(c)), and is inputted to the data terminal of the latch circuit 5 via the switch 23 (FIG. 2(f)). As described above, in the information unrecorded area, when the binary signal corresponding to the average amount of received light is at a high level, the pickup 1 is located on the track. Therefore, by latching this on-trunk signal in the launch circuit 5 using the edge pulse output from the edge pulse generation circuit 4, an accurate lock-in signal can be obtained.

When the pickup 1 moves from the unrecorded area to the recorded area, the detection means 22 detects the RF multiplied signal (FIG. 2(b)) and outputs a high level detection signal, so the switch 23 is activated.
is switched to the binarization circuit 11 side. Therefore, the envelope detection means 10 detects the RF multiplied signal envelope signal, and this envelope signal is binarized by the binarization circuit 11, and the signal is supplied to the launch circuit 5 via the switch 23 (FIG. 2(f) )). In this case, when the binary signal of the envelope signal is at a high level, the pickup 1 is positioned on the track. Therefore, by latching this on-track signal in the latch circuit 5 using the edge pulse output from the edge pulse generation circuit 4, an accurate lock-in signal can be obtained.

As shown in FIG. 3, an OR circuit 31 is provided in place of the switch 23 in FIG. The AND circuit 32 is activated by a signal obtained by inverting the output of the detection means 22 by the inverter 34.
3 are respectively controlled by the output of the detection means 22, and the OR circuit 3
1 may be input to a data terminal of a latch circuit 5 as a means for generating a timing signal.

In the above, an embodiment has been described in which the reflectance increases in the information recording section and the phase of the signal corresponding to the average amount of received light on the track and between the tracks is reversed compared to the case in the non-information recorded section. generates a timing signal for lock-in using an RF signal envelope, so the level of the signal corresponding to the average amount of light received in the recording section will be the same on the track and between tracks, or the average amount of light received will be the same. Even on discs where the corresponding signal is less on a track than between tracks, 1
The present invention can be applied.

〔effect〕

As described above, the present invention provides a tracking pull-in device including a pickup for recording or reproducing information by irradiating light onto a disk, and a first pickup for detecting a signal corresponding to the average received amount of reflected light from the disk from the output signal of the pickup. a second detection means for detecting an RF multiplied signal envelope signal of information recorded on the disk from the output signal of the pickup; and a third detection means for detecting the presence or absence of the RF multiplied signal.
a tracking error generating circuit that generates a tracking error signal from the output signal of the pickup; When the detection means does not detect the RF multiplied signal, a means for generating a timing signal for locking in the tracking servo loop is provided from a signal corresponding to the average received light amount and a tracking error signal, and when the RF multiplied signal is present, the RF multiplied signal is detected. The timing signal that locks in the 1-racking servo loop is generated by using the signal, and by using the signal corresponding to the average amount of received light when the RF multiplication signal is not present, so it can be used regardless of the type of disc. ,
A timing signal for lock-in can be generated accurately.

[Brief explanation of the drawing]

Figure 1 shows the tracking pull-in of the present invention! A block diagram of position A, FIG. 2 is its operation waveform diagram, FIG. 3 is a block diagram of other embodiments, FIG. 4 is a block diagram of a conventional tracking pull-in device, and FIGS. 5 to 7 are its operation. FIG. 1...Pickup 2...Tracking error generation circuit 3.7.11...Binarization circuit 4...Edge pulse generation circuit 5...Latch circuit 6...Light amount detection means 10...
・Envelope detection means 21° pass bypass filter 22...Detection means 23...Switch or above Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Factor (e) (h) J-(i)

Claims (1)

[Claims] a pickup that irradiates light onto a disk to record or reproduce information; and a first pickup that detects a signal corresponding to the average amount of received light reflected from the disk from the output signal of the pickup.
a second detection means for detecting an envelope signal of an RF signal of the information recorded on the disk from an output signal of the pickup; and a third detection means for detecting the presence or absence of the RF signal. , a tracking error generation circuit that generates a tracking error signal from the output signal of the pickup; and when the third detection means detects the RF signal, a tracking error signal is generated from the envelope signal of the RF signal and the tracking error signal; The present invention is characterized by comprising means for generating timing signals for locking in the tracking servo loop from the signal corresponding to the average amount of received light and the tracking error signal when the detection means of No. 3 does not detect the RF signal. Tracking retraction device.