JPS61280032A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To vary servo loop gains of focusing and tracking for every disk and to perform stable recording and reproduction by providing a detecting means which detects the transmitted light of light converged on an optical disk and deciding an optical disk which has a different reflection factor according to its detection output. CONSTITUTION:A disk 7 is rotated, an objective 5 is moved to an area where there is not track groove, and an optical pickup 6 is moved forcibly to a specific position. In this state, a semiconductor laser is turned on to emit light, transmitted light from the disk 7 is obtained by a photodetector 14 and detected by a detector 15, and a sampling output is averaged to calculate the transmissivity. A servo loop gain switching part 21 is set on the basis of the transmissivity of each disk. A driving voltage is applied to the optical pickup 6 with a servo loop gain set by the servo loop gain switching part 21 to operate the objective in a focusing and a tracking direction, thus allowing the laser light to follow up a specific track.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording and reproducing apparatus for optically recording and reproducing information on an optical disc.

Conventional technology Conventional disc discrimination is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-11957.
As shown in Publication No. 2, this is accomplished by writing a disk identifier in a predetermined location and reading the disk identifier when accessing for the first time.

The problem that the invention seeks to solve However, in this discrimination method, the focus.

The identifier cannot be read unless tracking is controlled. Therefore, in the case of optical discs having different reflectances, focus and tracking control becomes unstable, and there is a problem in that it may not be possible to distinguish between optical discs.

The present invention has been made in view of this point, and it distinguishes between optical discs with different reflectances without applying focus and tracking control, and stabilizes the focus and tracking servo loop gain by changing the focus and tracking servo loop gains for each disc based on the discrimination result. This allows for recording and playback.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a detection means for detecting J% excess light condensed on an optical disk, and discriminates optical disks having different reflectances according to the detection output. It is.

Function: With the above-described configuration, the present invention obtains the transmittance of the optical disk by detecting the transmitted light of the light focused on the optical disk, and discriminates optical disks having different reflectances without applying focusing or tracking servo. Furthermore, by switching the servo loop gain for each determined optical disc, it is possible to record and reproduce optical discs with different reflectances.

Embodiment FIG. 1 shows a block diagram of an optical recording/reproducing apparatus according to this embodiment of the present invention. Reference numeral 1 denotes a laser light source which emits a constant amount of laser light, such as a semiconductor laser.

A collimator lens 2 converts the laser beam from the laser light source 1 into parallel light.

3 is a polarizing beam splitter, and 4 is a λ/4 wavelength plate.

5 is an objective lens; 6 is an optical pickup that operates the objective lens 6 in the focusing and tracking directions;
It is composed of known driving means such as a voice coil motor. 7 is a disk.

A half mirror 8 divides the reflected light from the disk 7. 9 is a condensing lens, and 1o is a dividing mirror. Reference numeral 11 denotes a focus control photodetector, which is composed of two divided photodetectors, and obtains a focus error signal from the differential output of each photodetector. Reference numeral 12 denotes a tracking control photodetector which has the same configuration as the focus control photodetector 11 and obtains a tracking error signal. A photodetector 13 receives reflected light from the disk 7. A photodetector 14 receives transmitted light from the disk 7. A detector 15 detects the output of the photodetector 14 and outputs an envelope. 1e is a sample and hold circuit. 17 is an A/D converter which converts the output sampled at 16 into a digital signal. Reference numeral 18 denotes a signal processing section composed of a microcomputer or the like. 19
The subtracter is used to obtain the differential output of the two-split focus control photodetector. 2o is a subtracter that obtains the differential output of the two-divided tracking control photodetector. 21
is set to the gain set by the signal processing section 19 in the servo loop gain switching section. 22 is a drive circuit that operates the optical pickup with the focus gain and tracking gain set by the servo loose gain switching section 21.

Regarding the optical recording and reproducing device configured as above,
The operation will be explained below. Laser light emitted from a laser light source 1 passes through a collimator lens 2, becomes parallel light, passes through a polarized beam splitter 3, a λ/4 wavelength plate 4, and is focused onto a disk 7 by an objective lens 6. First, the disk 7 is rotated, the objective lens 6 is moved to an area where there is no track groove, and the optical pickup 6 is forcibly moved to a predetermined position. In this state, the semiconductor laser is made to emit light, the photodetector 14 obtains transmitted light from the disk 7, the wave detector 16 detects the light, and the sampling output is averaged to calculate the transmittance. The servo loop gain switching section 21 is set according to the transmittance of each disk, and the optical pickup 6 is returned to its initial position. The laser beam is again focused on the disk 7, but at this time, the information track of the disk 7 is rotating with surface and center runout, so in order to focus the laser beam on a predetermined information track, focus error, which will be described later, is applied. A driving voltage is applied to the optical pickup 6 at the servo loop gain set by the servo loop gain switching unit 21 based on the signal and the tracking error signal to move the objective lens 6 in the focusing direction and the tracking direction, and the laser plate 4 By passing through twice, the incident light 9
The 0' polarized light passes straight through the polarizing beam splitter 3 and enters the half mirror 8. Reflected light is half mirror 8
The light is split into two directions, one of which enters the condenser lens 9 and the other enters the photodetector 13. The reflected light exiting the condensing lens 9 is divided by the splitting mirror 5-1o, one of which is focused on the focus control photodetector 11, and the other light is focused on the tracking control photodetector 12. The focus control photodetector 11 and the tracking control photodetector 12 are composed of two divided photodetectors, and by obtaining the differential output from each photodetector with subtractors 19 and 20, a focus error signal and a Create a tracking error signal. Shift focus control and tracking control are performed by feeding back these error signals to the drive circuit 22 of the optical big hour processor described above through the servo loop gain switching section 21. The output of the photodetector 13 in this state is used as a reproduction signal.

The cartridge used here has the structure shown in FIGS. 2a and 2b, and 24 is a hole for detecting transmitted light, which is provided corresponding to a hole 26 made for input and reflection.

Effects of the Invention As described above, according to the present invention, discs with different reflectances can be discriminated without focusing or tracking control, and the servo loop gain can be switched according to each reflectance. You can also record and play,
It is extremely effective as an optical recording and reproducing device that is compatible with read-only disks that utilize uneven grooves, write-once disks that utilize perforation and phase change, and eraser disks.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of an optical recording/reproducing device according to an embodiment of the present invention, and FIGS. 2a and 2b are a longitudinal sectional view and a plan view of a cartridge used in the device. 1...Light source, 2...Collimator lens, 3...Polarized beam splitter, 4...
・λ/4 wavelength plate, 5...Objective lens, 6...
...Optical pickup, 7...Optical disc,
8...Half mirror 19...Condenser lens, 10...Division mirror, 11...Focus control photodetector, 12...・Photodetector for tracking control, 13...Photodetector for RF, 14...Photodetector for transmitted light, 15...
...Detector, 1e...Sampling hold circuit, 17...A/D converter, 18...
・Signal processing unit, 19... Focus subtractor,
2Q... Tracking subtractor, 21...
...Servo loop gain switching section, 22...
Drive circuit, 23... Cartridge, 24...
... Hole for transmitted light, 26 ... Hole for input and reflection. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (2)

[Claims] (1) A means for condensing light from a light source onto an optical disk via an objective lens installed in a lens section and an actuator, and a means for moving the objective lens in the normal direction of the optical disk; What is claimed is: 1. An optical recording/reproducing apparatus comprising: a detecting means for detecting transmitted light of the light condensed by the optical disc; and detecting the transmitted light to discriminate between optical discs having different reflectances. (2) The optical recording/reproducing apparatus according to claim 1, wherein transmitted light is detected and the servo loop gain is switched depending on the reflectance of the optical disc. (2) The optical recording and reproducing apparatus according to claim 1, wherein the cartridge into which the optical disc is inserted has a hole formed on the side opposite to the objective lens for detecting transmitted light.