JPS61139982A - Optical information reproducing device - Google Patents

Abstract

PURPOSE:To perform accurate reproduction even when a different kind of medium is used by providing a medium detecting means which detects the kind of a recording medium loaded in an optical information reproducing device according to the level of a playback signal. CONSTITUTION:A control circuit 13 rotates a spindle motor 2 when detecting the recording medium 1 being loaded on the device. At the same time, gains of a laser driving circuit 4, an automatic focusing control circuit 6, an automatic tracking control circuit 7, and a preamplifier 5 are set. The respective set values are so determined that an EDRAW type recording medium having the smallest playback signal level has the optimum level. Simultaneously, the peak value of the playback signal from an optical head 3 is detected and supplied to an A/D converter 12. The circuit 13 decides on the type of the loaded medium 1, i.e. EDRAW, DRAW, or ROM on the basis of the value of the detection signal. The gains of the circuits 4, 5, and 7 and amplifier 5 are set on the basis of the decision result and a different type of medium is reproduced securely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information storage device, and particularly to reproduction signal processing of an optical disk device that handles different types of disks.

[Prior Art] Means for optically storing information include write-once optical disks, rewritable magneto-optical disks, and ROM (read-only memory) disks. A write-once optical disc uses a laser beam to create irregularities on the disc surface according to the information to be stored, and the stored information is read out based on changes in the amount of reflected light. A rewritable magneto-optical disk uses a laser to cause magnetization reversal on the disk surface, and reads information using the magnetic Kerr effect or the like. Further, in a ROM type disk, bits corresponding to information are formed in advance, and the information signal is read out using changes in the amount of reflected light by laser light.

When recording using these discs, the type of disc to be recorded may be selected depending on whether the information can be erased after recording or the information must be stored for a long period of time. In other words.

When recording information that you don't mind erasing later.

That is, when a storage device is used as a temporary storage device, a magneto-optical disk is used, and information that needs to be permanently stored is recorded on an optical disk. This makes it possible to use disks efficiently. By the way, since the basic structure of the information recording and reproducing device is almost the same for different types of discs, it is conceivable to use a common drive device.

However, in this case, the output level of the reproduced signal in the signal readout system, especially the information signal output component, changes by several tens of times due to differences in the reflectance of the disk surface and differences in the readout principle depending on the type of disk. . When trying to reproduce information using the same reproduction system, if the smaller reproduced signal is used as a reference, a huge dynamic range will be required, and if the larger one is used as a reference, noise and signal levels will be too low when the signal is small. The problem arises.

[Object of the Invention] The present invention has been made by focusing on the above-mentioned conventional problems, and even when using the same optical information recording/reproducing device and different types of discs, the signal readout system can be improved. The object of the present invention is to provide a device that can accurately reproduce a recording medium by stabilizing the output level.

[Embodiments of the Invention] Generally, the level of a reproduced signal tends to vary depending on the type of recording medium. For example, if the playback signal level (preamplifier output value) of an EDRAW type recording medium (magneto-optical disk) is 1, the playback signal level of a DRAWROM type medium (optical disk) will be several times that level. On the other hand, with a ROM type recording medium, the level of the reproduced signal can be obtained about 10 times that level. If these reproduced signals are used as they are, the above-mentioned problems will occur. Therefore, the present invention identifies the type of recording medium installed in the optical information recording/reproducing apparatus based on the output magnitude of the reproduced signal, and provides recording/reproducing conditions according to the type.

FIG. 1 is a block diagram showing one embodiment of the present invention.

There are various kinds of recording media l, and all of them can be installed.

The optical helad 3 has a semiconductor laser optical system and actuators for autofocus and autotracking built into it.

The autofocus control 6 is a circuit that controls the autofocus mechanism within the optical head, and its gain can be switched by a signal from the control circuit 13.

O)) The luffing control circuit 7 is a circuit that controls the auto-tracking mechanism within the optical helad 3. The gain of the autofocus control circuit 6 can be changed by a signal from the control circuit 13. Preamplifier 5
is a circuit for amplifying the reproduced signal obtained from the recording medium 1, and the gain of this preamplifier 5 can also be changed by a signal from the control circuit 13.

The recording signal processing circuit 8 is a circuit that processes recording data transmitted from the outside into a form that can be recorded on the recording medium 1, and the laser drive circuit 4 processes the recording data transmitted from the outside into a form that can be recorded on the recording medium 1. This is a circuit that turns on and off the semiconductor laser in port 3.

The reproduced signal processing circuit 9 is a circuit that processes the reproduced signal from the preamplifier 5.0 circuit 10.11°12 is a circuit that detects the level of the reproduced signal from the preamplifier 5.
Envelope detection circuit lO, peak hold circuit 11.
It is composed of an A/D converter 12.

The control circuit 13 has the function of a medium type detection child that detects the type of recording medium 1 according to the magnitude of the reproduction signal output from the A/D converter 12.

FIG. 2 is a diagram showing waveforms at various parts of the circuits to, 11 and 12.

FIG. 2a shows a reproduced signal from the preamplifier 5 obtained when the optical head 3 is stopped. This reproduced signal is subjected to envelope detection by the envelope detection circuit 10 as shown in FIG. 2C, and further, the peak value Vp of the envelope detection output is obtained by the peak hold circuit 11 as shown in FIG. 2C. This peak value Vp
is converted into a digital signal by the A/D converter 12 and taken into the control circuit 13. The A/D conversion is
The control circuit 13 executes this at an appropriate timing.

FIG. 3 is a flowchart showing the operation of the above embodiment.

The control circuit 13 constantly monitors whether the recording medium 1 is attached to the apparatus. If it is detected that the storage medium l is attached, the spindle motor 2 starts rotating,
The recording medium 1 rotates at a predetermined rotational speed. Furthermore, in order to detect the reproduction signal, the laser power, autofocus control circuit (AT) gain, and preamplifier gain are
It is set to a predetermined value by the control circuit 13.

Each set value above is the ED with the lowest playback signal level.
This is the optimum level for RAW type recording media. At the same time, the optical device 2 and 3 move onto the recording area of the attached recording medium 1.

In this state, a reproduced signal is output from the preamplifier 5 as shown in FIG. 2a. Therefore, the control circuit 13 sends an A/D conversion start signal to the A/D conversion circuit 12 and detects the peak value of the reproduced signal. Based on the value of this detection signal, the type of the mounted recording medium 1 is determined (i.e., EDR
AW?

(Determine whether it is DRAW or ROM).

The laser power is determined by the result of this determination.

Set AT gain and preamplifier gain to optimal values.

If it does not correspond to any medium, no further processing will be performed.

[Effects of the Invention] According to the present invention, even when the same optical information reproducing device is used with different types of discs, the output level in the signal readout system is stabilized.
It has the effect of being able to accurately reproduce recording media.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a diagram showing waveforms of main parts in the above embodiment. FIG. 3 is a flowchart showing the operation of the above embodiment. 1...recording medium, 3...optical head,
4... Laser drive circuit, 5... Preamplifier, 6... Focus control circuit, 7...
...Auto tracking control circuit, 8...Record signal processing circuit, 9...Reproduction signal processing circuit, lO
...Envelope detection circuit, 11...
Peak hold circuit, 12...A/D converter,
13... Control circuit.

Claims (2)

[Claims] (1) Optical information comprising a medium type detection means for detecting the type of recording medium loaded in the optical information reproducing device according to the magnitude of the reproduction signal of the optical information reproducing device. playback device. (2) In claim 1: An optical information reproducing device, wherein the types of the information recording medium include a magneto-optical disk, an optical disk, and a read-only optical disk.