JPS60157737A - Recording and reproducing device of optical information - Google Patents

Abstract

PURPOSE:To attain record/reproduction for both a read-only optical disk and an optical disk capable of write/erasion with the same deck, by using a critical angle method for focusing and then a heterodyne method and a push-pull method with selection in response to the type of a recording medium for tracking. CONSTITUTION:The output given from a 4-split photodiode 17 is applied to a driving coil 19 of a focus actuator through a phase compensating circuit and a driver 18 after an operation carried out to obtain a focus error signal by a critical angle method. For tracking error signals, a T.E1 obtained by a heterodyne method and a T.E2 obtained by a push-pull method are available. Both T.E1 and T.E2 are led to comparators 20 and 21 and then changed to an H level from an L level when the error signal exceeds a certain band value. The outputs of both comparators function as the control signals of analog switches 22 and 23. Then either one of both switches is turned on to apply the tracking error signal to a coil 25 of a tracking actuator through the phase compensating circuit and a driver 24.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an information recording and reproducing device using an optical recording medium.
In particular, it relates to a method of pivoting the optical pickup.

[Prior art]

FIG. 1 is a diagram showing a reproduction system of a compact disc 1c. It is a disk substrate made of single-layer polycarbonate, and has pits with a depth of 1/4 of the wavelength λ of the VC laser laser on the surface. The surface of the pin 9 is further coated with an aluminum reflective film, and an organic protective film 3 is coated on top of that. The configuration of the optical biliquan that reads out the beam signal is a collimator lens 5 that uses a laser diode 4 as a light source to correct the emitted light into a parallel beam, a polarizing beam splitter 6 that converts the optical path of the beam, and a laser beam splitter 6 that converts the optical path of the beam. A λ/4 plate 7 that suppresses the returning light to the diode and rotates it by 90 degrees in the direction of the narrow beam, an objective lens 8 that focuses the laser beam and reads out the recording pitch, and a disk camera. critical angle prisms 9 and 4 for detecting the returned light of
It consists of each part of the divided photodetector 10. The focusing and tracking methods of this pickup use the critical angle method and the heterodyne method, respectively. In the critical angle method, when the laser irradiation spot deviates from the focal position, the return light from the diode that enters the critical angle prism 9 becomes diverging light or converging light and enters the 4-segment photodetector 1. O11 is used because the intensity distribution of the light is asymmetrical. FIG. 2 shows an arithmetic circuit for obtaining the focus error signals F and E, and performs the following arithmetic operations.

7=(PD2+PD3)-(PD1+PD4) Therefore, by determining this value 7'+: + or -1, it can be determined whether the objective lens 8 is too close or too far from the disk.

On the other hand, in the heterodyne method for tracking, tracking error signals T and E are obtained by performing phase detection 11 on the following fls2 S2 = (FD2 + PD4) - (PD1 + PD3) using the sum signal E + 1 - PD 1 + PD 2 + PD 3 + PD 4 of all photodiode elements as a reference. Now, in contrast to such a read-only type compact disc playback system, there is an additional write type so-called D.
Optical memory devices using EAW disks and magneto-optical disks that can be erased and rewritten have been developed. Therefore, in the future, compatibility between such read-only disks and optical disks that can be written and erased will become an issue. Figure 3 is a diagram showing the configuration of DRAW, or magneto-optical, media. . A pre-group 13 with a width of 07 μm and a thickness of λ/8 is formed on the substrate 12, and a recording layer 14 and a protective layer 15 are laminated thereon.A laser beam 16 detects this pre-group and outputs data ( d will be recorded on this group. Now, here is the selection of the group [!l
In this case, the push-pull method is used. The push-pull method detects the distribution of diffracted light from the groove using a photodetector, and the beam spot is aligned with the groove. Take advantage of the fact that asymmetry is observed on the photodetector when looking at the left, V or right side.
The figure shows a calculation circuit for obtaining this error signal. If the 4-divided photodiodes are assigned VC numbers in the track direction as shown in the figure, the above-mentioned asymmetric signal is obtained by the difference signal=(PD1+PD21-IPD3+PD4). In addition, according to the critical angle method, focus error signal = difference signal = (PDl + P'D4) - (PD2 + PD3
) can be obtained from

〔the purpose〕

As is clear from the above description, the recording format is different between a read-only optical disc and a writable/erasable optical disc, and the tracking method during playback is also different. However, from a user's standpoint, it is desirable that the two types of discs be recorded and played back on the same deck. The present invention solves these problems and improves the performance of recording and reproducing devices.

〔overview〕

The present invention retains the critical angle method and heterodyne method that have been conventionally used for compact discs, and furthermore
As a tracking method, a push-pull method compatible with rewritable discs is performed using the same optical head, and the tracking method is devised to be the most condensed to the recording format of the disc.

〔Example〕

FIG. 5 is a diagram showing the configuration of an embodiment according to the present invention.

The output from the 4-split photodiode 17 is calculated to obtain a focus error signal using the critical angle method: (PD2+
After PD3)-(PD1+PD4), the phase compensation circuit and driver 18fφ apply the voltage to the drive coil 19 of the funnel actuator.

On the other hand, the tracking error signal is calculated = (PD2+PD
Two systems are prepared: T and Fl obtained by heterodyne detection of the difference signal detected by A) - (PI)1 + PD3), and ↑E2 obtained by performing the calculation: (PDI + pD2) - (PD3 + PD4), Ru. The former is the heterodyne method, and the latter is the prishpull method. In the present invention, the reason why these two methods are not re-extended is that the error detection line f and the photo sensor fall in the far field, and the focus error detection and push-pull tracking error detection are mutually effective. This is because it can be divided into orthogonal areas on the sensor. Tracking error detections T, F, 1 and T, E2 are led to comparators 2θ, 21 which respectively detect the magnitude of the error signal, and when the error signal exceeds a certain threshold value, it changes from L level to H level. The output of this comparator is the analog switch 22.
23, and turns on one of the switches T, E1, T, and E2, and outputs the tra-soking error signal, the phase compensation circuit, and the driver 24'f! r
The coil 25 of the torsion ring actuator is connected via the coil 25.

Figure 6 shows the above operation time chart. After inserting the disc in Idenoki 1, the play switch is turned on, and the disc starts to rotate. Immediately after the disc rotates, the focus mode starts and when the zero chronograph point of the focus error signal is detected. The optical pickup enters a blank state and autofocusing is performed. Since the laser beam crosses the data track of the disk only in the focused state, tracking error signals T, E1, T, and Fi2 are generated. Therefore, when the error signal exceeds f1, the output changes from L level to H level. In Figure 6, T
, 1 exceeds the threshold, indicating that comparator 1 has become H. On the other hand, in T, the length of the recording format on the disk and the tracking means as described above matched (
6, the error signal is small and the comparator 2 does not change. Therefore, the most suitable tracking method for the format of the disc inserted into the player is automatically selected, and the error signal train is passed on to the phase compensation circuit via the nine analog switches, and at the same time as the error signal crosses zero. Tracking search is turned on.

In addition, in the diagram showing T, Bi, T, and E2, the part indicated by the dotted line does not show how to dispose of the error signal without applying the voltage. Furthermore, once the output of the converter reaches the H level, it is held in that state unless it is reset. Furthermore, it is of course possible to select the front station tiger knocking method manually, so there is no need to explain this point b5. .

〔effect〕

As is clear from the above embodiments, the present invention can establish disc compatibility in a player, that is, a playback-only audio compact disc with different recording formats, a video disc, and a RAY disc that can be re-expanded for writing. , magneto-optical disks that can be erased and written to, etc. can be recorded and played back on the same player. Of course, in terms of software, there are further problems such as the difference in the old method of error code 1, but since the stiffness is a problem with the circuit meter, compatibility is f! -It can be said that it is easy to establish and discontinue. The present invention can solve the problem on the hardware, that is, the data writing format of the disk, and the I7 is
A tends to be a lot of fun because it becomes a multifunctional rice cake.

The most difficult application is a compact chisel for playback only.
In addition, it is possible to record re-expanded optical discs using the same player, and its practical functionality is extremely high (c).Also, it can be used as computer memory and can be rewritten with read-only software programs. User programs can be processed on the same disk, on the same disk, or on multiple disks.

Furthermore, it is possible to play compact discs and image files in the same player.

As stated above, the present invention has excellent practical value.

[Brief explanation of the drawing]

Figure 1 shows the compact disc playback system with Q and R0.
The diagram shows the force tracking method for compact discs (the 5th [ne 11 η' RAW- or the 141 yen information for magneto-optical discs). Figure 5 is a program diagram between central offices, and Figure 6 is a time chart of the present invention. 1... Board 2... Data bit 6... - Storage film 4...Laser゛Iode 5...Collimator lens 6...Side light prism λ 7...-Plate 8...Objective Lens?...Critical angle prism 10...Photodetector 11...Heterotine detection circuit 12...
... Substrate 13 ... Pregroup 14 ... Recording layer 15 ... Lumbar membrane 16 ... Laser beam 17 ... Four-division photo diode 18.24
・・・・・・Phase compensation and driver circuit 19.25・
...Actuator coil 2r], 21...
・Comparator: 2', 23...analog switch or more Applicant Suwa Seikosha Co., Ltd. Figure 1 Figure 2M Figure 3 Figure 4

Claims (2)

[Claims] (1) In a device that optically records and reproduces information by converging the light emitted from a laser diode onto a recording medium, the critical angle method is used for focusing the optical pickup, the heterodyne method is used for the Toller J-King method, and the An optical information recording and reproducing device that uses both push-pull and push-pull methods, and is characterized in that the selection of the push-pull method can be switched automatically, or by an external switch, depending on the format of the recording medium. (2) Using the heterodyne method and push-pull method for tracking, the disk is rotated for a short period of time immediately after loading the optical recording medium, and the tracking error signal is inspected while focusing. When a predetermined threshold value is exceeded, the condition is detected by a comparator, and the analog switching is controlled by the output of this comparator 1 node. An optical 171 information recording and reproducing apparatus according to claim 1, characterized in that one of the two is automatically selected.