JPS63222335A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute the stable tracking control without reducing the capability of track seeking by using track mark on a recording medium to perform tracing in the phase difference method and counting continuous grooves to seek a track. CONSTITUTION:The recording medium having both of concentric circle-shaped or spiral continuous groove and pit-shaped track mark is used, and two detection signals obtained from a light quantity detector 3 are subjected to waveform shaping by circuits 4a and 4b to obtain two digital detection signals C and d, and phases are compared with each other by a phase comparing means 5 to obtain a tracking error signal E from a phase difference pulse corresponding to the phase difference, and the tracking control is executed. A detection signal H obtained from a signal quantity detector 6 and difference means 7 is subjected to waveform shaping to obtain one pulse for one continuous groove which a head transverses, and the direction in which the head transverses the track is detected by a direction detecting means 13, and a track is seeked in accordance with the information.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical information recording/reproducing device, and particularly to tracking control and traverse control thereof.

2. Description of the Related Art In recent years, optically recordable and reproducible recording media and systems using these have been put into practical use. These record information on minutely wide information tracks, so
Precise tracking control is generally required during recording and reproduction. In order to perform tracking control, it is necessary to detect a tracking error, and this is normally performed using optical means.

In order to detect this tracking error optically, at least two interference lights generated in a direction perpendicular to the track are detected.
Two methods are known: one method is to detect the difference between the two light receiving elements, and the other method is to receive the interference light also generated in the track direction. The former is called the Puseongyupul method. Among the latter methods, the tracking error is detected from the phase difference between the signals output from two parts of a plurality of light receiving elements that receive detection light and output electrical signals (hereinafter referred to as the phase difference method). ) has a simple optical system and is not easily affected by warping of the recording medium.

An example of the above-mentioned conventional optical information reproducing device will be described below with reference to the drawings.

FIG. 6 shows tracking error detection means using a phase difference method in a conventional optical information reproducing apparatus. In FIG. 6, ■ is an optical head, 2 is a recording medium, and 4 is a recording medium.
a and 4b are shape shaping means, 5 is a phase comparison means, 8 is a tracking control means, and 11 is a light receiving element (light receiving means). The recording medium 2 has a disc shape, and information can be recorded in a concentric or spiral shape. The operation of the conventional tracking error detection means configured as described above will be explained below.

Two types of detection signals A and B are output from the light receiving element 11 provided in the optical head 1. The detection signal A and the signal B are output signals from different light receiving sections of the light receiving element 11. In reality, each signal is composed of a plurality of signals and is often added together externally, but here each is regarded as one signal. These detection signals are the sum of the diagonal directions obtained by dividing the far-field image of the eclipsed light formed on the light receiving element into four in the direction in which the information trunk is projected and in the direction perpendicular to this. It is known that a phase difference occurs between these detection signals due to a tracking error (for example, see Japanese Patent Laid-Open No. 52-93222). The waveform shaping means 4a and 4b are for shaping the waveforms of the detection signal A and the signal B, respectively, to obtain digital detection signals, respectively. A tracking error signal can be obtained by comparing the phases of the two digital detection signals thus obtained by the phase comparison means 5.

Tracking error detection using the phase difference method is suitable for playback-only optical heads such as heads for digital audio and video discs. This is due to the interference light generated by the edge of the side of the track when the push-pull method is used (see Figure 3(a)).
), whereas the phase difference method is based on detecting the corners (see Fig. 3) of the discontinuous portions of the track. For this reason, discs with continuous tracks such as recording/reproducing optical discs are not suitable, but JP-A-56-
As shown in Publication No. 22227, etc., if the trunk mark has a pit shape and information is recorded between the pits, it is possible to use the trunk mark to use the phase difference method. can.

Problems to be Solved by the Invention However, this configuration has a problem in that track seeking takes time.

In other words, in order to perform track seeking at high speed, by counting the number of tracks that the head has passed, the current position of the head (relative to the recording medium) can be recognized with one track accuracy, and the desired position can be recognized with one track accuracy. It is necessary to have each trunk reach the same trunk. In the case of a continuous groove track, whether or not the trunk has been passed can be determined by monitoring the tracking error signal. However, when a recording medium having pit-shaped track marks is used to perform tracking control using the phase difference method, problems arise. This is because when the seek speed becomes approximately the same as the rotational speed of the disk, the track may be passed through without crossing the track mark, causing a counting error. If information is filled between track marks, the information string can be regarded as a track, but in the case of a recording/reproducing type, it is possible that the information string has not been recorded yet.

The present invention has been made in view of this point, and uses a recording medium having both continuous grooves (groups) formed in a concentric circle or spiral shape and a focus-shaped track mark, and uses the trunk mark described above. By adopting a configuration in which phase difference method tracking is performed using the track seek function, and track seeking is performed by counting the above-mentioned series 'ftyJI, stable tracking control can be realized without deteriorating the track seeking ability. be.

Means for Solving the Problems In order to solve the above problems, the optical information recording/reproducing device of the present invention compares the phases of these detection signals with a first light amount detection device having at least two outputs. a second light amount detection device comprising phase comparison means and further having two outputs;
It comprises differential means for taking the difference between them, and counting means for counting the number of times the output signal exceeds an appropriate threshold, and further comprises a phase comparison between the phase comparison means and the output of the differential means. and direction detection means for detecting the moving direction of the light spot with respect to the recording medium.

Effects The present invention has the following effects due to the above-described configuration.

That is, the two detection signals obtained from the first light amount detection device are waveform-shaped into two digital detection signals, and the phase comparison means compares the phases of these digital detection signals to determine a phase difference corresponding to the phase difference. A tracking error signal is obtained by outputting a pulse, and tracking control is performed using this signal. Furthermore, by waveform-shaping the detection signal obtained from the second light amount detection device and the differential means, one pulse is obtained for each group that the head has passed, and the direction detection means detects whether the head crosses the track at that time. The track seek can be performed based on this information.

Embodiment Hereinafter, an optical information recording/reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the optical information recording/reproducing apparatus of the present invention. FIG. 1 is a block diagram showing the main parts thereof. In FIG. 2, 1 is an optical head, 2 is a recording medium, 3 is a (first) light amount detection device, 4a and 4
b is a waveform shaping means, 5 is a phase comparison means, 6 is a (second)
A light amount detection device, 7 is a differential means, 8 is a tracking control means, 9 is a counting means, 10 is a traverse control means, 11 is a light receiving element (light receiving means), 12 is a (third) light amount detection device, 13 is a direction It is a detection device. The recording medium 2 is disc-shaped and has bit-shaped track marks 2p and continuous groups 2g formed in concentric or spiral shapes as shown in FIG. The optical head 1 reads these from the recording medium 2 and maps the far-field image onto the light receiving element 11. The light amount detection device 3 combines two detection signals A and B from the output of the light receiving element 11. Details of this are shown in FIG. Detection signals A and B are detected by the four light receiving sections 110a, 110b, which constitute the light receiving element 11 included in the optical head l.
110c, 110d, respectively 110a and 110c
, 110b and 110d. When the optical head l has a tracking error with respect to the track mark 2p, the phases of a plurality of diffracted lights generated at the corner of the specularly reflected light and the track mark 2p vary, and the intensity distribution of the far-field image, which is a composite of these lights, becomes third. It changes as shown in figure (b). As a result, a phase difference occurs between detection signals A and B. 4a and 4b are waveform shaping means which remove low frequency components from the detection signals A and B, and then perform waveform shaping by comparing with zero potential to output digital detection signals C and D. A phase comparison means 5 compares the phases of the digital detection signals C and D and outputs a phase difference signal, that is, a tracking error signal E. After this tracking error signal E is processed by the tracking control means 8,
The optical radar l or its objective lens is driven to cancel the tracking error. Tracking control is performed in this way.

Detection signals F and G are received by light receiving sections 110a and 110, respectively.
d, the sum signal of 110b and 110c.

The far-field image of group 2g is represented by the sum of the interference light caused by the light diffracted in the vertical direction and the specularly reflected light, and its intensity distribution is shown as in Fig. 3 (al).The detection signal F
By taking the difference between and G (assuming this signal is H), it means that a tracking error signal in the so-called pushinable method has been detected.

That is, when the optical head crosses one track, the signal H changes from + to 0 to - (or vice versa).

By slicing this signal with an appropriate threshold value, one pulse is obtained, and by counting this pulse with the counting means 9, it is possible to know the number of tracks traversed from the start of traversal to the present time. The traverse control means 10 executes the traverse while referring to the output of the counting means 9. As a result, precise track seek can be performed.

Figure 4 shows the state of interference light generated by the track mark 2p and the group 2g. (b) shows the state when the light is away from the track mark 2p.The interference light generated by the group 2g is vertically symmetrical in the notation shown in FIG. The slave group 2g, which does not give , has no effect on phase difference tracking.

The track mark 2p does not affect the track count only in the following case, that is, when the optical height of the trunk mark 2p is λ/4 (k: integer value), the interference light is shown in Fig. 4 1cJ. It is symmetrical in the diagonal direction. At this time, even if a differential is used between the left and right sides to obtain the track cross signal, the amounts of light on both sides are equal, so they are canceled. Therefore, the track mark 2p is not counted as a track.

Figure 5 shows that the light spot moves on the recording medium at S-8'' or T.
→T' is a signal waveform diagram showing the signals of each part of the above embodiment when crossed. That is, waveforms A, B, C, D, E,
H corresponds to that shown in FIG. 2, respectively.

Next, the functions of the light amount detection device 12 and direction detection device 13 will be described. With only the configuration described so far, a counting error is likely to occur when entering a desired track.

For example, when the recording medium 2 is rotating eccentrically, the swing of the track due to the eccentricity may overtake the optical spot (head) during track seeking, and at this time the optical spot begins to move backward relative to the recording medium. . As a result, even though the cumulative value of the counting means 9 is approaching the desired track, it may actually be moving away from the desired track. In order to prevent this, it is necessary to be able to detect the direction of movement of the light spot with respect to the recording medium.

The light amount detection device 12 and direction detection device 13 are intended for this purpose. The light amount detection device 12 is a four-person addition system. Let the output signal be 1. The direction detection device 13 detects the moving direction of the optical spot with respect to the recording medium by comparing the output signal I and the output signal H of the differential means 7 with each other. The situation is shown in Figure 6, P→P', Q→Q°
is an output signal that represents the trajectory of the light spot when it crosses the recording medium in different directions (for example, from inner to outer circumference, from outer circumference to inner circumference), and represents the change in the amount of reflected light when it crosses a trunk mark or group. To detect. If the change in the amount of reflected light due to the track mark is greater than that due to the group, the envelope of the output signal (■) takes the maximum value between the groups. On the other hand, the output signal H is 0 on and between groups.
and takes the maximum and minimum values alternately. Therefore, when the track mark row is crossed from P-P' (inner circumference to outer circumference), the output signal H changes from 0 to -, and Q -Q'
(outer circumference→inner circumference), the output signal H changes from - to +, so if these differences are detected, the moving direction of the light spot can be detected.

However, as described in the conventional example, if the seek speed becomes too fast, track marks will be skipped, making it impossible to detect the direction. However, since direction detection becomes necessary near the time when the seek speed becomes O (for example, when entering a desired track), there is no problem at all in practice.

Effects of the Invention As is clear from the above explanation, the present invention uses a recording medium having both concentric or spiral groups and pit-shaped trunk marks, and uses the track marks to record data. By performing phase-difference tracking and counting the groups while detecting the moving direction of the optical spot from both the track marks and groups, trunk seek is performed without deteriorating the track seek ability. , it has become possible to realize stable tracking control.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a main part of an optical information recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of an optical information recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 3 is a track diffraction diagram. An explanatory diagram showing the state of light, Fig. 4 is an explanatory diagram explaining the tracking error signal detection method, and Figs. 5 and 6 are signal waveforms at various parts of the optical information recording and reproducing device shown in Fig. 1. 7 are block diagrams of a conventional optical information recording/reproducing device. 1... Optical head, 3.6... Light amount detection means, 4a, 4b... Waveform shaping means, 5...
. . . Phase comparison means, 7 . . . Differential means, 8.
... Tracking control means, 9 ... Counting means, 10 ... Traverse control means, 11 ...
. . . Light receiving element, 12 . . . Light amount detection means, 1
3... Direction detection device. Name of agent: Patent attorney Toshio Nakatashi (1 person) Figure 3 a - False Ward ~ , Sorry for the expense - α Mei ~ ~ 10 Figure 5 Figure 6 Q◆σ

Claims (1)

[Claims] An optical information reproducing device using a recording medium having both continuous grooves formed in a concentric circle or a spiral shape and pit-shaped track marks, wherein irradiation light is projected onto the information track of the recording medium. an optical head that forms a light spot and detects the reflected light or transmitted light; a light receiving means provided on the optical head and having at least three light receiving sections; a first light amount detection device for combining outputs; a tracking error detection means for extracting a phase difference component of a detection signal obtained from the first light amount detection device and outputting a tracking error signal; a tracking control means for adjusting the position of the light spot, and a second light amount detection device for combining two outputs from the output of the light receiving means; and a counting device for counting the number of times the detection signal obtained from the differential means exceeds an appropriate threshold, and a third light amount detection device for adding up all the outputs of the light receiving means. An optical information recording/reproducing apparatus comprising: a direction detecting means for detecting a moving direction of a light spot with respect to the recording medium by extracting a phase difference component with respect to the output of the differential means.