JPS59215027A - Recording and reproducing system - Google Patents

Abstract

PURPOSE:To eliminate an error by generating a timing signal distinguishing an address area and a data area and changing over the gain of a reproducing amplifier so as to make both reproducing levels equal thereby making the levels of both the signals constant. CONSTITUTION:A reproducing amplifier 131 is provided with gain control, a write gate pulse 134 representing the recorded area generated from a controller 2 is given to a gain control terminal and the gain is switched so that an output of the reproducing amplifier is equal at a rugged pit and a density pit. Thus a data without error is obtained by pulsating the signal through a comparator 132 (Vc; another input to the comparator) and a peak detecting circuit 133.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a recording and reproducing method for an optical disk device that optically records and reproduces information, and in particular, the present invention relates to a recording and reproducing method of an optical disk device that optically records and reproduces information, and in particular, the present invention relates to a recording and reproducing method for an optical disk device that optically records and reproduces information. The present invention relates to a recording and reproducing method suitable for recording and reproducing an optical disc in which different types of data signals are recorded.

[Background of the invention]

In recording and reproducing optical discs, when optically reproducing an address signal recorded as uneven pits like on a digital optical disc and a data signal recorded as grayscale bits by making holes of about 1 μm in the recording film, for example, the unevenness A difference in level occurs between the reproduction signals from the pits and the light/dark bits depending on the optical characteristics of the optical head for recording and reproduction and the shape of the pits. When converting this reproduced signal into digital data using a comparator or peak detection circuit,
If there is a level difference between the two signals, the comparator level will be different or the peak detection circuit will deviate from the dynamic range, resulting in a large amount of errors occurring in one of the signals.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an error-free optical disc recording and reproducing system in which the levels of both signals are kept constant.

[Summary of the invention]

The present invention is characterized in that the gain of the reproduction amplifier is switched by the recording timing pulse for recording the dark and light pits so that both reproduction levels are equal.

[Embodiments of the invention]

Examples of the present invention will be described in detail below. FIG. 1 shows an overview of an optical disc recording/reproducing apparatus. Data input device 1
The data input from the
After that, the light is further guided to the recording circuit 3 and directly drives the semiconductor laser 4.

The light emitted from the semiconductor laser 4 passes through the lens 5. Prism 6 and further aperture narrowing lens 7f: 1μ passes through and onto optical disk 8
It is converged to a spot of about m. The optical disk 8 consists of a guide groove 9 with a depth of λ/8 and an address area 10 of uneven pits with a depth of λ/4, assuming that the semiconductor laser wavelength is λ. ) is several tens of t1
It is deposited to a thickness of m. Data is recorded by pulse-oscillating the semiconductor laser 4 at approximately 10 mW to the address section 10.
This is done by forming dark and light pits of about 1 μm in recording areas other than the above. To reproduce data, the semiconductor laser 4 is caused to oscillate DC at a constant output, the spot focused on the optical disc is positioned on the guide groove 9, and the reflected light from the optical disc 8 is narrowed down by a lens 7, a prism 6, and a lens. 11 to a photodetector 12 for photoelectric conversion. Furthermore, the reproduction signal is pulsed by the reproduction circuit 13, demodulated by the controller 2, and then displayed on the data output device 14. The reproduced signal photoelectrically converted by the photodetector 12 is determined by the optical characteristics and the shapes of the uneven pits and the light and dark pits, and a difference occurs in the level between the uneven pits and the light and dark pits. With reference to FIG. 2, a case will be explained in which the level of the address portion of the concave and convex pits is smaller than the level of the i-recording area of the dark and light pits. This is a case where the depth of the uneven pit deviates from λ/4, and the reproduced signal becomes as shown in FIG. 2 (1). If this signal is passed through the reproducing circuit 13 as it is, the comparator level will be different between uneven pits and dark/dark pits, and if the dynamic range of the peak detection circuit is small, an error will occur.

Therefore, by using a reproducing circuit as shown in FIG. 3, the reproduced signal can be made constant. In FIG. 3, the reproducing amplifier 131 has a gain control, and the write gate pulse 134 (shown in FIG. 2 (2)) indicating the recording area generated by the controller 2 is connected to the gain control terminal, and the output of the reproducing amplifier is The gain is changed so that the difference is equal between the uneven pits and the light and dark pits (see Figure 2).
3)). After this, comparator 132 (Vc
(the other input of the id comparator) is pulsed through the peak detection circuit 133 to provide error-free data. The gain control characteristics of the reproduction amplifier 131 are as shown in FIG. 4. For example, if the level differs by 6dj3 between the uneven pits and the light and dark pits, the gain control voltage will be 0.5V for the uneven pits and 1 for the light and dark pits. Just set it to .5V. On the other hand, if the dark and light pit portions are smaller than the uneven pit portions, the reproduced signal level can be kept constant by performing gain control in the opposite manner to the above.

〔Effect of the invention〕

As explained above, according to the present invention, when reproducing information recorded in different formats on an optical disk, the signal can always be kept constant, which has the effect of eliminating errors caused by differences in recording formats. There is.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an optical disk recording/reproducing apparatus showing an embodiment of the present invention, FIG. 2 is a diagram explaining its operation, and FIG. 3 is a circuit diagram showing the main part of an embodiment of the present invention. FIG. 4 is a diagram showing the gain control characteristics of the reproducing amplifier. 1...Data input device, 2...Controller, 3.
...Recording circuit, 4...Semiconductor laser, 8...Optical disk, 9...Guide groove, 10...Address section, 12.
... Photodetector, 13 ... Regeneration circuit, 131 ... Regeneration amplifier, 132 ... Comparator, 133 ... Peak detection circuit, 14 ... 1(
eye!

Claims (1)

[Claims] 1. In a recording and reproducing method that optically records and reproduces information on an optical disc, which consists of an address area that is pre-recorded on the disc, such as an address signal, and a data area that can record data signals other than the address area, the address A recording characterized in that a timing signal is generated to distinguish between an area and the data area, and the gain of a reproduction amplifier is switched according to the timing signal so that the reproduction level of the address area and the reproduction level of the data area are equal. Playback method.