JPH0644347B2 - Optical recording / reproducing device - Google Patents

Description

The present invention records a signal at a high density by irradiating light from a light source such as a laser with a light of a small diameter onto a disk or the like coated with a recording material capable of optically recording. The present invention relates to a reproducible optical recording / reproducing device.

When signals are recorded at high density in the above optical recording / reproducing apparatus, it is necessary to relatively move the disc and the optical head in correspondence with the track pitch formed by the recording signals on the disc. The higher the recording density, the higher the accuracy of the feeding mechanism required.

Further, in such an optical recording / reproducing apparatus, the recording density is also restricted by the vibrations transmitted from inside and outside the deck.

On the other hand, some kind of optical guide track is provided on the entire surface or a part of the disk, and a signal is recorded while following the optical guide track using a conventionally known tracking technique. By providing the optical guide track on the entire surface or a part of the disk, it is possible to obtain an optical recording / reproducing apparatus in which the precision of the feeding mechanism between the optical head and the disk is not severe and which is resistant to vibration and the like.

FIG. 1A shows an example of a disk having an optical guide track G over the entire circumference of the disk. This optical guide track has a spiral shape or a concentric circular shape, and is configured by arranging thin strips having different shades or different reflectances from each other, or a concave or convex shape that changes the phase structure of light in the irradiation light. It is a groove that is continuously given, or a shape that gives direction to reflected light, such as V
It may be a V-shaped groove.

FIG. 1 (B) shows an example of an optical guide track formed by light and shade. In this figure, T ₁ indicates track spacing and T ₂
Indicates the width of the optical guide track on which the signal is recorded,
In the transparent substrate U, U ₁ indicates a light incident surface, U ₂ indicates a recording material surface, and an arrow F indicates an optical guide track direction.

FIG. 1 (C) shows an example of an optical guide track having a concave groove. T ₁ ′ represents a track interval, T ₂ ′ represents a width of an optical guide track on which a signal is recorded, U ₁ ′ represents a light incident surface on a transparent substrate U ′, and U ₂ ′ represents a recording material. Showing the face,
The arrow F'indicates the direction of the track.

Generally, in an optical recording / reproducing device or reproducing device,
It is an essential requirement to precisely irradiate the recording material surface of the disk or the surface of the disk on which the signals are recorded with a light beam that is minutely focused, and for this purpose, conventionally known focus control technology is used. When a disc having a guide track as shown in FIG. 1 is used, the influence when light crosses the optical guide track often appears in some form as a disturbance in the focus control system. Further, for example, when the disk and the optical head are moved at a relatively high speed in order to search for a specific portion of the guide track at a high speed, the speed at which the optical guide track traverses differs corresponding to the moving speed. Then, the frequency of the disturbance affecting the focus control system also changes. In the optical recording / reproducing apparatus, it is an essential condition that the focus control is always functioning stably without being disturbed by the above disturbance. Therefore, in an optical recording / reproducing device using a recordable / reproducible disc having an optical guide track, when the focus control is pulled into the disc or after crossing the optical guide track at a high speed, or another recording / reproducing device. It is necessary to confirm whether the focus control is working properly when checking the function of.

FIG. 2 is a diagram showing an optical recording / reproducing apparatus having a conventional light beam focus control system utilizing the astigmatism of reflected light. In FIG. 2, 1 is a semiconductor laser which is a light source, 2 is a condenser lens for condensing the light from the semiconductor laser 1, and 3 and 4 are substantially rectangular light of the semiconductor laser 1. A concave and convex cylindrical lens for making a circle, 5 is a tracking mirror, 6 is an aperture lens for narrowing down to a small spot light, 7 is a disc capable of optically recording and reproducing information such as a video signal, and 8 is a disc A motor 9 is an aperture lens driving device for performing focus control, and the aperture lens 6 is driven according to the surface deviation of the disk 7.
The distance between the diaphragm lens 6 and the disk 7 is always kept constant by moving the. As the diaphragm lens driving device 9,
For example, a voice coil of a speaker is used. 10 is a light beam splitter, 11 is a single convex lens,
Astigmatism is given to the reflected light together with the convex cylindrical lens 4. 12 is A, B, C and D as shown in FIG.
It is a photodetector divided into four parts. In FIG. 2, the light beam indicated by the solid line a is the light beam in the direction in which the lens action of both cylindrical lenses 3 and 4 is effective, and the light beam indicated by the broken line b is the lens effect of both cylindrical lenses 3 and 4. The light beams in the directions that do not work are shown. Since the reflected light of the light beams a and b from the disk 7 is given astigmatism by the cylindrical lens 4 and the single-convex lens 11, the shape of the light on the photodetector 12 changes depending on the surface deviation of the disk 7. Change. Therefore, the focus control can be performed by utilizing the change in the shape of the light. Specifically, the photodetector 1 including A, B, C and D in FIG.
2, DI = (amount of received light of A + amount of received light of C) − (B
A focus error signal for focus control can be obtained from the received light amount of + the received light amount of D). However, A ₁ , A ₂ , A ₃ and A ₄ are amplifiers, and R is a resistor.

FIG. 4 shows the state of the focus error signal. In the graph of FIG. 4, the vertical axis represents the focus error signal V and the horizontal axis represents the second.
The distance X between the diaphragm lens 6 and the disk 7 in the figure, that is, the position of the disk 7, is shown in FIG.
The state where the light beam is narrowed down most (just focus)
The distance between the diaphragm lens 6 and the disk 7 is longer than the just focus distance, that is, in the direction away from the diaphragm lens 6, as (d), (e), and (f). , (A), the distance is shorter than the just focus distance, that is, the aperture lens 6
It shows the state of the focus error signal which is approaching to. As can be seen from FIG. 4, for example, in the focus control method using astigmatism, if the disk 7 is moved away from the diaphragm lens 6 from the position (e) due to surface deviation or the like, the polarity of the focus error signal is It will be reversed and the focus control will not be able to be pulled to the proper position. Therefore, the focus control pull-in range is limited to the left side of the position (e) in FIG. 4, and at the moment when the focus control loop is closed and focus control is performed, the distance between the diaphragm lens 6 and the disk 7 is as shown in FIG.
It must be on the left side of the position of (e).

Further, FIGS. 1 (B) and 1 (C) show specific examples of the disc structure, but these are the discs with the simplest structure, and the light reflecting surfaces of the discs themselves are transparent substrates U, U ′. There are light incident surfaces U ₁ and U ₁ ′ and recording material surfaces U ₂ and U ₂ ′.
In addition to this, by forming a film having poor thermal conductivity in the vicinity of the recording material surface in order to increase the recording sensitivity, there are discs having a multi-layered structure and a number of light reflecting surfaces.

Now, for example, if focus control is applied to the disk shown in FIG. 1 (B), there is a possibility that the light may enter the incident surface U ₁ and the recording material surface U ₂ for focus control. In addition, the servo system may be disturbed by disturbance and the voice coil itself may go out of the compensation range to the servo system.

Furthermore, as described in FIGS. 3 and 4, FIG.
In starting the focus control operation of the disc of (B), assuming a surface deviation within a certain amount of the disc 7,
It is necessary to close the focus control loop when the aperture lens 6 is moved away from the disc 7 and gradually brought closer to the disc 7 and within the focus control pull-in range described with reference to FIG. On the other hand, when the diaphragm lens 6 is gradually brought closer to the disk 7, a focus error signal of the same shape as that in FIG. 4 is also generated on the light incident surface U _{1 in} FIG. 1 (B). In particular,
When the reflectance of the recording material film and the reflectance of the transparent base material U are substantially equal to each other, focus error signals having substantially the same amplitude are generated. Therefore, when the focus control loop is closed, Fig. 1 (B)
There are cases where focus control is applied to the light incident surface U ₁ and cases where it is entered into the recording material surface U ₂ , and when focus control is applied to the light incident surface U ₁ , focus control of the recording material surface U ₂ is performed. There will be no. In this case, since the thickness of the base material U is generally about 1 mm, the surface U ₁
It is not possible to detect the guide track on the surface U ₂ with a good S / N ratio by the minute light focused on. Therefore, if focus control is pulled into this unfavorable surface, the guide track crossing signal cannot be detected.

In FIG. 3, the sum of the light receiving outputs of A, B, C and D of the four-divided photodetector 12 is output to the output terminal S of the amplifier A ₄ . Therefore, with focus control applied, FIG.
As shown in FIG. 5A, when light crosses the optical guide track G on the disk 7 as shown by an arrow, FIG.
A pulse-like guide track crossing signal as shown in FIG. The time width of the guide track crossing signal changes depending on the speed of the light beam that crosses the optical guide track G. Further, the number of guide track crossing signals generated per one rotation of the disk 7 is also determined by the eccentricity of the disk 7.

Further, when the tracking control is performed by the tracking mirror 5 in FIG. 2, the light beam scans only one guide track, so that the guide track crossing signal is not generated.

When a signal is already recorded on the guide track subjected to the tracking control, the reproduced signal is output to the output terminal S of the amplifier A ₄ shown in FIG. On the other hand, when no signal is recorded on the optical guide track, no signal is output to the output terminal S.

Therefore, an object of the present invention is to provide an optical recording / reproducing apparatus capable of confirming the state of focus control on a disc and reliably performing focus control on a signal recording surface.

An embodiment of the present invention is shown in FIG. That is, this optical recording / reproducing apparatus is obtained by adding the circuit block shown in FIG. 6 to that shown in FIG. 2, and irradiates the disk 7 having the optical guide track G with light of a laser or the like with a very small diameter. An optical recording / reproducing device for recording / reproducing a signal on or along the optical guide track G by means of the focus control circuit means for locating the focus of the irradiation light on the recording material surface of the optical guide track G of the disk 7. I, focus control pull-in circuit means II for pulling the focus of the irradiation light within the focus control range of the focus control circuit means I in response to the focus control command signal, and the focus of the irradiation light is the focus of the focus control circuit means I. A pull-in detection circuit means III that outputs a signal for stopping the operation of the focus control pull-in circuit means II upon detecting that it has reached a pull-in position within the control range; Guide track crossing signal detection circuit means IV for detecting a guide track crossing signal generated when the irradiation light crosses the optical guide track 7 and the pull-in detection circuit when the guide track crossing signal detection circuit means IV is not output. The focus control pull-in circuit means V is re-activated after a lapse of a certain time after the operation of the means III, and the focus control is performed by the guide track crossing signal output to the output terminal S of FIG. It is configured so as to confirm that it is operating reliably, that is, that the focus control has surely entered the recording material surface U ₂ and is kept on.

Hereinafter, this optical recording / reproducing apparatus will be described in detail. In FIG. 6, the focus control error signal (the signal of the terminal DI in FIG. 3) is input to the terminal DI. A focus control element (aperture lens driving device 9) such as a conventionally known voice coil is connected to the terminal J. The sum signal (guide track crossing signal) output from the terminal S in FIG. 3 is supplied to the terminal S. Focus control ON (FO
N) A command signal is output to the terminal L when the focus control is off (F.OF).
F) A command signal is input.

Further, 21 is a phase compensation circuit of the focus control system, 22 is a switch for controlling ON / OFF of the focus control loop, the opening and closing of which is controlled by the signal of the terminal S ₁ , and when the terminal S ₁ is at a high level, it is closed and the terminal p ₁ And r ₁ are connected. Reference numeral 23 denotes a drive circuit of a focus control element (aperture lens drive device 9) such as a voice coil.

Reference numeral 24 denotes a switch, and the capacitor 25 is connected to the power source −V ₂ , +
By charging and discharging at V ₁ , a loose lamp output V _c shown in FIG. 7 (D) is generated. When this voltage is supplied to the drive circuit 23 through the switch 26, the diaphragm lens 6 is moved away from the carrier disk 7 at + V ₁ and then −.
The diaphragm lens gradually approaches the disk 7 by the signal toward V ₂ .

27 is an integrating circuit for integrating the focus error signal input to the terminal DI, and 28 is a level comparator, which compares the focus error signal shown in FIG. 4 with the reference level V _thl, and the focus error signal is the reference level V _thl. When it goes higher, it generates a signal and resets the flip-flop 29.

Reference numeral 29 indicates a flip-flop for pulling in the focus control.
Reference numeral 30 is an inverter, 31 is a delay pulse generating circuit composed of a monostable multivibrator, etc., 32 is a flip-flop for controlling ON / OFF of focus control, 33 is an OR gate, 3
4 is an AND gate, 35 is an inverter, 36 is an integrating circuit for integrating the guide track crossing signal, 37 is a level comparator for comparing the threshold voltage V _th2 with the output of the integrating circuit 36, 38 is an AND gate, R ₁ And R ₂ represent resistance.

Next, the operation of this optical recording / reproducing apparatus will be described with reference to FIG.

First, as a desired state, when the focus control is off, the switch 22 is off between p ₁ and r ₁ , the switch 24 is on between q ₂ and r ₂ , the switch 26 is off between p ₃ and r ₃ , and the flip-flop is on. Both of the groups 29 and 32 are in the reset state, that is, both Q ₁ and Q ₂ are low level.

First, a signal (F.
OF) is input as shown in FIG. This pulse sets the flip-flop 32, and Q ₂ becomes high level as shown in FIG. 7 (B). At the same time, the flip-flop 29 is also set, and the Q ₁ signal becomes the seventh signal.
It goes high as shown in Figure (C). In addition, when the Q ₁ signal goes high, the switch 24
p _2, r ₂ between ON and the switch 26 between terminals p _3, r ₃ is turned on, the supply voltage of the charging and discharging waveforms shown in FIG. 7 (D) is the iris lens driving device 9 such as a voice coil Then, the diaphragm lesbian 6 is moved away from the support disk 7 and gradually approaches the disk 7.

As the diaphragm lens 6 is _moved closer, the focus error signal becomes larger than the reference level V _thl as described with reference to FIG. 4, and the level comparator 28 receives the pulse shown in FIG. 7 (E). (Indicating that the distance of the disk 7 is within the focus control pull-in range) occurs. The flip-flop 29 is reset by this pulse, the Q ₁ signal becomes low level, and the switches 24 and 26 are returned to the desired states. While at the same time the AND gate 38, by Q ₂ signal is high, since the other input also becomes high level, the high level to indicate the output to FIG. 7 (F), p of the switch 22 by the signal Turn on between ₁ and r ₁ to turn on the focus control loop. In addition, the delay pulse generating circuit 31 detects that the Q ₁ signal is reset to low and
As shown in (G), a pulse delayed by time t is generated. If the focus control loop is turned on by the output of the AND gate 38 and focus control is applied to the recording material surface U ₂ (Fig. 1 (B)), the terminal S is guided as shown in Fig. 7 (H). A track crossing signal is input. This signal is supplied to the integrating circuit 36.
And the threshold voltage V _th2 is compared by the level comparator 37 to obtain a high level output as shown in FIG. 7 (J). When the output of the level comparator 37 becomes high level, the output of the inverter 35 becomes low level, the output of the delay pulse generating circuit 31 does not pass through the AND gate 34, and the focus control is maintained. In this case, when the surface on which the guide track exists is focused, the guide track crossing signal is generated because the guide track on the disc is several tens to several hundreds with respect to the circle drawn by the light spot on the disc. It has an eccentricity of μm, for example, in the case of a guide track with a track pitch of several μm,
Unless tracking control is performed, the light spot always crosses the guide track and generates a guide track crossing signal.

On the other hand, when the guide track crossing signal is not generated after the focus control loop is turned on, the output of the level comparator 37 remains at the low level, so the delay pulse generation circuit 3
The output pulse of 1 (FIG. 7 (G)) passes through the AND gate 34 (shown by a broken line in FIG. 7 (K)), which sets the flip-flop 29 through the OR gate 33. As a result, the focus control loop (switch 22) is turned off, the switches 24 and 26 are operated again, and the focus control pull-in operation is repeated.

The fact that the focus control has been entered as described above is confirmed by detecting the guide track crossing signal, and although not mentioned in the text, the tracking control is turned on thereafter. This makes it possible to capture a specific optical guide track and record / reproduce a signal to / from the optical guide track.

Further, as described above, when the tracking control is turned on, the guide track crossing signal is not generated, so the delay pulse generator 31 for confirming the focus control generates a pulse before turning on the tracking control. It is necessary to finish the inspection.

It is also necessary to confirm the focus control function during various operations of the optical recording / reproducing apparatus. Even in this case, by turning off the tracking control system once and confirming the existence of the guide track crossing signal,
You can check whether the focus control system is operating normally. on the other hand,
The optical recording / reproducing apparatus often switches the tracking control system on and off in the middle of its function. For example, when searching a predetermined optical guide track at high speed, it is necessary to move the optical head and the disk relatively at high speed. In such a case, generally, the focus control is kept on and the tracking control system is turned off to carry out high-speed transfer. By detecting the presence of a guide track crossing signal while the tracking control system is turned off, the focus control system can be confirmed and inspected. Further, the focus control system can be checked during the known jumping operation (generally, the tracking control system is turned off to perform the jumping operation) when the required optical guide track density inspection is performed. . Inspecting at a time other than when the focus control is pulled in as described above, for example, by applying a signal to the terminal M (shown by a dotted line) in FIG. 6 at the moment when the tracking control system is off, the delay pulse generating circuit 31
By generating a pulse from, it is possible to confirm the state of focus control at that time.

As described above, the optical recording / reproducing apparatus of this embodiment always confirms the focus control function even if there are disturbance factors as described in (1) to (5) below in the focus control system, and in the case of an abnormality. In order to perform high-density recording / reproducing and high-speed retrieval, the disk is provided with an optical guide track to perform the operation again.

(1) When the focus control is pulled in, there is a possibility that the disc 7 may be pulled in by the wrong reflection surface.

(2) Disturbance may occur due to damage to the disk or unevenness of the unevenness, and the focus control may be lost.

(3) When performing high-speed search, the vibration of the optical recording / reproducing device and other factors may cause disturbances and defocus control.

(4) The recording material may not function sufficiently due to differences in reflectance.

(5) A signal traversing the optical guide track is introduced into the focus error signal of the focus control system and becomes a disturbance to disturb the focus control system.

Although FIG. 6 shows an embodiment in which the present invention is configured as a hardware, if this function is implemented by using a microcomputer that controls and manages the entire optical recording / reproducing apparatus,
More reasonable and effective actions can be performed.
That is, the microcomputer grasps the state of all devices such as on / off of tracking, presence / absence of high speed transfer, necessity of jumping function and output level of the level comparator 37 shown in FIG. Therefore, the state of focus control can be arbitrarily incorporated into each of these states, and a more rational configuration than the configuration of FIG. 6 can be achieved.

As described above, the optical recording / reproducing apparatus of the present invention can confirm the state of focus control for the disc by the presence or absence of the guide track crossing signal, and for the unrecorded disc in which the signal is not recorded in advance by unevenness. However, there is an effect that the focus control on the signal recording surface can be surely performed.

[Brief description of drawings]

FIG. 1 (A) is a plan view of a disk having an optical guide track over the entire surface, FIGS. 1 (B) and 1 (C) are enlarged views of the main parts thereof, and FIG. 2 is a conventional optical recording / reproducing apparatus. FIG. 3 is a circuit diagram of a signal processing circuit for the focus error signal and the guide track crossing signal, FIG. 4 is a characteristic diagram of the focus error signal, and FIG. 5 (A) is an enlarged view of the guide track. FIG. 5 (B) is a waveform diagram of a guide track crossing signal, FIG. 6 is a circuit block diagram of a main part of an embodiment of the present invention, and FIG. 7 is a waveform diagram of each part thereof. I ... Focus control circuit means, II ... Focus control pull-in circuit means, III ... Pull-in detection circuit means, IV ... Guide track crossing signal detection circuit means, V ... Pull-in circuit re-operation circuit means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shangji Shunji 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenji Koishi, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-54-128707 (JP, A)

Claims (2)

[Claims] 1. An optical recording / reproducing apparatus for recording / reproducing a signal on or along the optical guide track by irradiating a disc having an optical guide track with light of a very small diameter. Focus control means for holding the focus of the irradiation light on the recording surface, focus control retracting means for retracting the focus of the irradiation light onto the signal recording surface, and tracking control means for tracking the irradiation light onto the guide track. Focus control according to the presence or absence of an output signal from the means for detecting a guide track crossing signal generated when the irradiation light crosses the guide track, and the tracking control means being inoperative, And a means for determining that the normal operation is performed. Recording and reproducing apparatus. 2. A method according to claim 1, further comprising means for reactivating the focus control retraction means when the means for detecting the guide track crossing signal generates an output signal indicating that the guide track is not detected. Optical recording and reproducing device.