JPS63220427A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To stably perform tracking control, by performing track seek by applying tracking by a phase difference method by using a track mark of pit shape, and counting consecutive grooves formed in a concentric circle or a spiral shape. CONSTITUTION:A recording medium 2 is formed in a disk shape, and also, the track mark 2p of pit shape and consecutive grooves 2g are formed in the concentric circle or the spiral shape on the medium. An optical head 1 reads those, and imprints the far-field patterns of them on a photodetector 11. A light quantity detector 3 synthesizes two detecting signals A and B from the output of the photodetector 11. Thus, it is possible to realize the tracking control stably without lowering the performance of the track seek by applying the tracking by the phase difference method by using the track mark, and counting the grooves.

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 trunking 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 trunk direction. The former is called the push-pull 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 a tracking error construction means using a phase difference method in a conventional optical information reproducing apparatus. In FIG. 6, 1 is an optical head, 2 is a recording medium, and 4 is an optical head.
a and 4b are waveform 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 operation of the conventional tracking error detection means, which is configured such that the recording medium 2 is disk-shaped and can record information concentrically or in a spiral and can record information in the form of 0 or more, will be described below.

Htil is transmitted from the light receiving element 11 provided in the optical head 1.
1 detection signals A and B are output. 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 made to be the sum of the diagonal directions obtained by dividing the far-field image of the detection light formed on the light receiving element into four in the direction in which the information trunk is projected and in the direction perpendicular thereto. For example, it is known that a phase difference occurs between these detection signals due to tracking error (for example, 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. 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 discs and video discs. This is because the push-pull method detects the interference light generated by the side edges of the track (Figure 3 a), while the phase difference method detects the corners of the interrupted portions of the track (Figure 3 b). This is because it is caused by

For this reason, recording/reproducing optical discs with continuous tracks are not suitable, but JP-A-56-222
As shown in Publication No. 27, etc., if the track mark is in the shape of a pit and information is recorded between the pits, it is possible to use the phase difference method using the track mark. 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 seek 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 the accuracy of one track, and the desired position can be determined by counting the number of tracks that the head has passed. It is necessary to reach each truck without fail. In the case of a continuous groove track, whether or not the track 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 mark may be passed through the trunk without crossing it, causing a counting error. If information is subtended 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 concentric or spiral-shaped continuous grooves (groups) and pier-shaped track marks, and uses the trunk marks as described above. By using a configuration in which phase difference method tracking is performed using a track seeker, and track seeking is performed by counting the continuous grooves, stable tracking control can be realized without reducing the track/seven seek ability. It is something.

Means for Solving the Problems In order to solve the above problems, the optical information recording/reproducing device of the present invention includes a first light amount detection device having at least two outputs, and a phase detector for comparing the phases of these detection signals. The apparatus further includes a second light amount detection device having at least one output, and a counting means for counting the number of times the detection signal exceeds a suitable value i.

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, one pulse is obtained for each group through which the head has passed, and track seek is executed 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. Second
In the figure, 1 is an optical head, 2 is a recording medium, 3 is a (first) light amount detection device, 4a and 4b are waveform shaping means, and 5
6 is a (second) sight detection device, 7 is a differential means, 8 is a tracking control means, 9 is a counting means, l
O is a traverse control means, and 11 is a light receiving element. The recording medium 2 is disc-shaped and has bit-shaped track marks 2p and continuous groups 2g formed in concentric circles or spirals 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 1 constituting the light receiving element 11 included in the optical head 1.
10a, 1lob, l1Oc.

110a and 1loc from 110d, respectively.

This is the sum signal of the outputs of 110b and 110d. When the optical head 1 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 trunk mark 2p vary, and the intensity distribution of the far-field image, which is a composite of these lights, becomes third. (in the figure). 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 them with zero potential to output digital detection signals C and D. Reference numeral 5 denotes a phase comparison means which 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 head l or its objective lens is driven so as to cancel the tracking error. Tracking control is performed in this way.

Detection signals F and FG are received by light receiving sections 110a and 11, respectively.
This is the sum signal of 0d, 110b and 110c. The far-field image of group 2g is represented by the sum of interference light due to specular reflection light diffracted in a direction perpendicular to the trunk, and its intensity distribution is represented as shown in FIG. 3(a). If the difference between the detection signals F and G (this signal is assumed to be H) is taken, a tracking error signal in the so-called pushinable method is detected. That is, when the optical head crosses one group, the signal H changes to +-0--<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 grooves traversed from the start of traversal to the present time. The traverse control means [0 executes the traverse while referring to the output of the counting means 9. As a result, precise track seek can be performed.

Fig. 4 shows the interference light generated by the trunk mark 2p and the group 2g.Ta) in Fig. 4 indicates that when the light spot emitted from the optical head 1 is near the edge before or after the track mark 2p, The mountain (mountain) indicates when the vehicle is off track mark 2p. Since the interference light generated by the group 2g is vertically symmetrical in the notation shown in FIG. 4, it does not affect the phase difference in the diagonal direction of the light receiving element 11. Therefore, the group 2g 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 track mark 2p is λ/4 (k: integer value), the interference light is As shown in (below, 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 amount of light on both sides is equal, so it is canceled out. Therefore, the track mark 2p is used as a trunk. Not counted.

FIG. 5 is a signal waveform diagram showing signals at various parts of the above embodiment when the light spot crosses the recording medium in a direction s-s' or TT'. That is, waveforms A, B, C,
D, E, and H correspond to those shown in FIG. 2, respectively.

Note that it is not always necessary to use the push-pull method to recognize groups.

It is also possible to simply detect the change in the amount of light when it passes through the group. For example, the light amount detection device 6 outputs the sum of the outputs of all the light receiving parts that make up the light receiving element 11, and the output signal is inputted to the counting means 9. In this case, the light amount detection device 6 will have only one output, so the differential means 7 will be unnecessary.

However, in this case, it is difficult to optically cancel the influence of the track marks, so another method (for example electrical) must be used.

Effects of the Invention As is clear from the above explanation, the present invention uses a recording medium having both concentric or spiral-shaped groups and focus-shaped track marks, and uses the track marks to perform positioning. By performing phase-difference tracking and performing trunk seek by counting the groups, stable tracking control can be achieved without reducing tracking seek ability.

[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 trunk diffraction FIG. 4 is an explanatory diagram showing the state of light; FIG. 4 is an explanatory diagram explaining the recording medium 2 and its reflected light; FIG. 5 is a signal waveform diagram at each part of the optical information recording/reproducing apparatus shown in FIG. FIG. 6 is a block diagram of a conventional optical information recording/reproducing device. 1... Optical head, 3.6... Light amount detection device, 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. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Figure 7'

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; a second light amount detection device for combining at least one output from the outputs of the light receiving means; and a detection signal obtained from the second light amount detection device. 1. An optical information recording/reproducing device comprising: a counting device for counting the number of times that a value exceeds an appropriate threshold;