JPH02139721A - Device for recording/reproducing optical information - Google Patents

Abstract

PURPOSE:To surely detect abnormality even if the speed of an objective lens is extremely low when AT control is failed by previously storing the position of an objective lens corresponding to one track piror to recording or reproducing and detecting tracking abnormality at the time of recording/reproducing based upon the stored contents. CONSTITUTION:The title device is provided with a means for comparing a recorded relative position with a detected relative position to detect tracking or focusing abnormality based upon the compared result. Since the position of the objective lens 110 against an optical head 121 correspondingly to one track is stored, abnormality can be more surely detected by comparing the position of the objective lens 110 in a scanning process even if the speed of the objective lens 110 at the time of releasing AT control is extremely low. Even when noise appears on a tracking error signal, it is unnecessary to average plural scans, so that the rapid operation of the device can be attained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention records information on an optical information recording medium, reproduces information recorded on the medium, and/or reproduces information recorded on the medium. The present invention relates to an optical information recording/reproducing device capable of erasing information, and particularly relates to an optical information recording/reproducing device capable of detecting an abnormality during autofocusing and/or autotracking.

(Prior Art) Information recording media used in optical information recording and reproducing devices that record information using light and read out the recorded information are in the form of disks, cards, tapes, etc. It has been known. Among these, card-shaped information recording media are generally lightweight and convenient to carry, and are expected to be in great demand as relatively large-capacity information recording media.

FIG. 5 schematically shows such a card-shaped information recording medium (hereinafter referred to as an "optical card") 101.
In the information recording area 102, information tracks 103 are formed in parallel arrangement. In addition, the information track 103
A track selection area for address and a track selection area for jump destination are provided at the front and rear of the 105. Also, outside the information recording area 102, the home position of the light beam spot is set. is formed.

On the information track of the optical card 101, an optically detectable recording bit string is recorded as information by scanning a light beam spot that is modulated according to the recorded information and narrowed down to a microspora. At this time, in order to accurately record information without causing problems such as the light beam spot crossing the information track, the irradiation position of the light beam spot must be set in a direction perpendicular to the scanning direction within the surface of the optical card. (auto tracking, hereinafter referred to as r AT J
) is necessary. In addition, the light beam is controlled in a direction perpendicular to the optical card surface in order to irradiate the light beam as a small spot with a stable size despite the bending or mechanical error of the optical card (auto7okakung, hereinafter referred to as rAFJ).
There is a need. In addition, the above AT also applies during playback and erasing.
, AF is required.

FIG. 6 shows a block diagram of such a device for recording and reproducing information on an optical card, and reference numeral 106 is a motor for driving the optical card 101 in the direction of the arrow in the figure. Further, reference numeral 121 denotes an optical head, which is equipped with a light source 107 such as a semiconductor laser, collimates light emitted from this by a collimator lens 108, and sends it to the objective lens 110 via a beam sinter 109. The light is focused on the recording track of the optical card 101. In addition, the light reflected by the recording track is transmitted through the beam splitter 109 and divided into υ2 by the next beam splitter 109. The light is focused on the photoelectric conversion element 116 for detecting a focusing signal. The signals obtained by the photoelectric conversion elements 115 and 116 are supplied to a tracking control circuit 117 and a focusing control circuit 118, respectively. The optical head 121 includes an objective lens 110, and a tracking coil 11 for operating along the optical card surface in a direction perpendicular to the information track.
1 and a focusing coil 112 for moving the objective lens 110 in a direction perpendicular to the surface of the optical card. Based on the commands from the control circuits 117 and 118, the tracking coil 111 and the tracking coil 1 are activated, respectively.
By passing a current through the lens 12, the objective lens 110 is moved to perform AT and AF.

In the figure, reference numeral 119 is a system controller that controls the optical recording/reproducing device, and it connects the motors 106 and 122 or the tracking control circuit 1 via a path 120.
17. Send a control signal to the focusing control circuit 118. Here, the motor 122 is used to move the optical head 121 in the direction shown in FIG.

(Problem to be Solved by the Invention) In such an optical information recording/reproducing device, when recording or reproducing information, AT control may be deviated due to an external impact or a defect in the record carrier itself. . In particular, during recording, the light beam spot deviates from the track to be recorded and moves in a direction that intersects with this, for example intruding into an adjacent already recorded track and superimposing new information on the information recorded here. There is a problem that it is recorded.

The present applicant has therefore proposed an optical information recording/reproducing device that detects a tracking abnormality by detecting the relative speed between an objective lens and an optical head and when the relative speed exceeds a predetermined value. In this case, a sufficient effect can be expected if the speed of the objective lens when AT control is removed is high, but if the speed of the objective lens is very small when AT control is removed, it is difficult to detect tracking abnormalities. It includes the problem that.

Additionally, the present applicant has previously proposed an optical information recording and reproducing device that stores tracking error signals including eccentricity in advance and detects tracking abnormalities based on the stored data. There is.

Here, in order to reduce the influence of medium defects specific to each track, averaging processing is performed for a plurality of tracks.

(Object of the Invention) The present invention has been made based on the above-mentioned circumstances. Before recording or reproducing on a record carrier, the objective lens position for one track is stored in advance, and based on the result, recording or reproduction is performed. It is an object of the present invention to provide an optical information recording and reproducing device that detects tracking abnormalities during reproduction.

(Means for Solving the Problems) Therefore, in the present invention, a light beam spot formed by a focusing means of an optical head is scanned along a plurality of information tracks formed in parallel on a recording medium. In an optical information recording and reproducing apparatus that records and/or straddles information by moving the information tracks, means for detecting the relative position of the light condensing means and the optical head with respect to the direction in which the information tracks are arranged in parallel; The apparatus comprises means for storing the value of the detected relative position, and means for comparing the recorded value of the relative position with the detected relative position, It is designed to detect focusing abnormalities.

(Function) Therefore, since the position of the objective lens with respect to the optical head is stored for one track, even if the objective lens speed is very low when AT control is removed, the position of the objective lens during the scanning process can be compared. Abnormalities can be detected reliably. Further, even if noise appears in the tracking error signal due to a medium defect, it is detected by comparing the objective lens positions, so there is no need to perform averaging processing over multiple scans, and high-speed operation of the apparatus can be realized.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to FIGS. 1 to 3. In the figure, the symbol l is the relative position (
The output signal a is supplied to the subtracter 2, and the output signal C of the subtracter 2 is sent to the window comparator 3 and the AD converter 41.
1C, an output signal d is supplied from the window comparator 3, and an output signal ・ is supplied from the AD converter 4 to the system controller 119. Further, the output signal f is outputted to the system controller 7119 Karaha DA converter 5, and the signal f from the DA converter 5 is given to the subtracter 2 as a negative signal.

In such a configuration, when recording on the optical card 101, the optical head 121 uses the objective lens 110.
Operate to perform AF and AT.

In this case, when the optical card is moved by one track during tracking, the light beam spot becomes xl in Figure 5.
Move from to x4. At this time, the relative position between the objective lens 110 and the optical head 121 changes due to the ski movement between the direction of the information track of the optical card 101 and the direction of movement of the optical card, and as a result, the relative position of the objective lens 110 and the optical head 121 changes. The output signal a changes as shown in FIG. At this time, since the output signal from the system controller 119 is O, the signal S to the subtracter 2 is also O, and is constant as shown in FIG. Therefore, the output signal C from the subtractor 2 is the signal a
It changes equivalently to . This signal C is converted into a digital signal e by the AD converter 4, and is sent to the system controller 1.
Hexagonal to 19. In the system controller 119, the digital signal is stored in a predetermined memory.

Next, when actually recording, when moving the light beam spot from xl to x2 (see Figure 3), the system controller 119 outputs the stored contents of the memory υ ahead as a digital signal f. do. The signal f is converted into analog by the DA converter 5, and this output signal is equivalent to the signal a mentioned above. 4 When the output signal a of the gas sensor 1 reaches the position x3, it changes in the same way.
The output signal C from subtractor 2 is zero. Then, if an external impact is applied at the x3 position, or the optical card 1
Suppose that the AT control has started to go out of order due to a defect in the 01. In this case, the difference between signal a and signal S becomes large,
The signal C gradually increases, and at the x4 position, the signal C becomes +
It becomes ΔV.

On the other hand, the window comparator 3 is designed to send out the abnormality detection signal d when the signal C is larger than 10 ΔV or smaller than −ΔV, so the above-mentioned A
If there is a deviation from the T control, an abnormality detection signal d is generated at position x4.
is sent to the system controller 119. Upon receiving the signal d, the system controller 119 reduces the power of the light source 107 from the recording power to the non-recording power, thereby avoiding writing to the adjacent information track when the AT control is lost. . In this way, multiple recording is prevented. The value of the abnormality detection voltage ΔV of the window comparator is preferably set to a value equal to or smaller than the track pitch of the information track 103.

In the embodiment shown in FIG. 1, the subtracter 2, the winco/parator 3. Although a DA converter etc. was used, such a hardware part was omitted and the system controller 119 was used.
The software part may have functions such as subtraction, conversion, and rate. Such an embodiment is shown schematically in FIG. In this case, subtractor 2
An alternative subtraction function is performed by comparing digital signals.

In addition, in the embodiment shown in Fig. 1, the signal before recording (Fig. 2 a)
It is assumed that the signals at the time of recording and the signal at the time of recording (FIG. 3a) are equivalent at position x1. This is because the same information track 103 is scanned twice, but the present invention is not limited to this form. That is, in a track different from the information track on which recording is actually performed, the signal a in FIG.
may be determined in advance. At this time, there may already be a difference between the recording signal a and the signal a at the position Xi. This occurs even if the AT control is normal, when the relative positions of the objective lens and the optical head are different. In this case, at position XI, the signal C is changed by Vdelta so that the signal C becomes zero,
During recording, it is sufficient to always apply an offset of Vd@lta to the signal.

Further, in the above embodiment, the moving direction of the light beam spot is described as being the same when storing the relative position and when comparing the relative position next time, but it may be in the opposite direction. At this time, it is only necessary to reverse the time when inputting to the memory or outputting from the memory. In addition, although we have explained that the moving speed of the light beam is the same when storing and when comparing, it is of course possible to use different speeds when storing and comparing, and the consistency is Of course, it can be processed by software.

(Effects of the Invention) As described in detail above, the present invention stores the objective lens position for one track in advance before recording or reproducing, and detects tracking abnormalities during recording or reproducing based on this. This makes it possible to reliably detect an abnormality even if the objective lens speed is very small when the AT control is lost. Furthermore, even if there is a defect in the recording medium and noise appears in the tracking error signal, it is necessary to perform multiple averaging processes in order to detect the movement of the objective lens using the objective lens position signal instead of the tracking error signal. Since there is no such thing, high-speed operation of the device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are graphs for explaining signal levels in the track direction, and FIG. 4 is a block diagram showing another embodiment of the present invention. , FIG. 5 is a plan view schematically showing an optical card, and FIG. 6 is a schematic configuration diagram of the entire optical information recording/reproducing apparatus. 1...Digital sensor, 2...Subtractor, 3...
Window comparator, 4...AD converter, 5.
・・DA converter, 101 ・・Optical card, 102・
... Information recording area, 103 ... Information track, 10
4.104'...Track selection area, 105...
Home position, 106...Motor, 107...
Light source, 108... Collimator lens, 109... Beam lens, 110... Objective lens, 111.
... Tracking coil, 112 ... Focusing coil, 113.114 ... Condensing lens, 11
5,116... Photoelectric conversion element, 117... Tracking control circuit, 118... Focusing control circuit,
119... System controller, 121... Optical head, 122... Drive motor.

Claims (1)

[Claims] Information is recorded and/or recorded by scanning a light beam spot formed by a focusing means of an optical head along a plurality of information tracks formed in parallel on a recording medium
Or in an optical information recording and reproducing device that performs reproduction,
means for detecting the relative position of the light condensing means and the optical head with respect to the direction of parallel arrangement of the information tracks; means for storing the value of the detected relative position; and the stored value of the relative position. and means for comparing the value of the detected relative position, and detects an abnormality in tracking or focusing based on the result of the comparison. .