JPS6266425A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To stably extract a clock signal by providing a means changing an amplitude of a reproducing signal from a clock corresponding to a recording information signal. CONSTITUTION:The information to be written is modulated by a modulation circuit 16 and the power of a light source 1 corresponds to two intensities PL, PH to information levels 0, 1. Since it is required to reproduce a clock, the power is not zero when the information is zero and the amplitude of an output waveform is not constant when the power of the light source changes as PH, PL. Then an amplifier 11 takes two amplification factors A and (PL/PH)A and when the modulation data of the optical beam is PL, the amplification factor is A and when PH, the factor is (PL/PH) switchingly. A signal S is an amplification factor switching signal sent to the amplifier 11 from the modulation circuit 16. Thus, the clock signal is stably reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to reproducing an fL7t clock track previously recorded on a recording medium using one of a plurality of light beams split from the same light source while The present invention relates to an optical information recording/reproducing device that records information on a recording track using a light beam.

[Prior art]

2. Description of the Related Art Conventionally, various types of media such as disks, cards, and tapes have been known for recording information using light and for reading recorded information.

Among these, optical recording media formed in the form of cards (hereinafter referred to as optical cards) are expected to be in great demand as mediums with a large storage capacity that are lightweight and convenient to carry.

By the way, the above-mentioned optical card creates an optically detectable recording pit array (
Information is recorded as an information track). At this time, in order to accurately record information without causing problems such as crossing of information tracks, the irradiation position of the light beam must be
It was necessary to control (auto tracking) in a direction perpendicular to the scanning direction. Furthermore, in order to correct variations in scanning speed, it was also necessary to obtain a clock signal. Therefore, the applicant decided to hire Drexler Techno H9.
According to a technical disclosure received from the Technology Corporation, there is a track (in a broad sense, an information pick including a tracking signal, a clock signal, etc.) for obtaining a tracking signal and a clock signal on the card in advance.
) J: A formed optical card has been proposed. A first example of such an optical card is shown in FIG.

FIG. 4 (4) is a schematic plan view of the optical card. Here, a clock signal is recorded on the optical card 31 in advance, and
A clock track 321 formed in the form of an intermittent broken line.
32. ．． 32. ．． 32. ...are arranged at equal intervals. A recording area 341 for recording information is provided between the clock tracker and the rear panel.

34,. 34. ...is provided.

FIG. 4(B) shows an enlarged view of the recording surface of the optical card 31. FIG.

When recording information on this optical card, the optical head 93
Irradiate the beam of the book, and each beam has a minute spora)S
,,s,,s,. These spots are scanned in the direction of arrow a by the relative movement of the optical card and the optical head, and a spot s in the middle is in the recording area 341.

Information is recorded as recording bit 35. Further, the reflected light from either spot S or S8 is guided to a detection means in the optical head, and a tracking signal is detected using a known method such as a so-called push-pull method. Based on this tracking signal, Spora) S, , S, , S3
The position of the spot S8 in the vertical direction (direction b) is moved integrally with the scanning direction of the clock track 321, thereby controlling the spot S8 to always accurately trace the clock track 321. Therefore, the recording pits 35 are accurately formed along the clock tracks 32□, and it is possible to prevent the information tracks from crossing over. At the same time, a clock signal is reproduced from the reflected light from the spot S1 or S, and is used as a clock for the recording signal. Also,
Reproduction of information is performed in the same manner.

FIG. 5 shows a schematic perspective view of an optical head of an optical information recording and reproducing apparatus that performs recording and reproducing on the optical card 31 shown in FIG. 4 (4). In the figure, a beam emitted from a light source 1 such as a semiconductor radar is collimated by a collimator lens 2 and divided into three beams by a diffraction grating 3. These beams are imaged by the objective lens 4 onto the optical card 31 as shown in FIG. 4 (4), and each has a beam spot S□.

s,,s,'1 is formed. Here, the optical card 31 is moved in the direction of arrow R by a drive means (not shown), and is scanned by the beam spot in the direction in which the tracking track and clock deviation extend.

The reflected light from the beams S1, S, S3 passes through the objective lens again, is reflected by a mirror 5, is projected onto a condenser lens 6, and onto photodetectors 7, 8.9 placed on the focal plane, respectively. be done. In this figure, the reflected light from the spora) S□ is incident on the photodetector 7, and a clock signal is reproduced.

[Problem that the invention seeks to solve]

However, since the three beams are split from one light source using a diffraction grating, etc., the beam spot S8 used to reproduce the clock is modulated by the information signal to be recorded, and is not modulated. A different waveform is output than when the clock track is reproduced with a light beam. Although many attempts have been made to derive a stable clock signal from this waveform, there is currently no efficient method.

[Problem 'f: Means for Solving the Problem 3 The above problem lies in the optical information recording/reproducing system which is characterized by having means for changing the amplitude of the reproduced signal from the clock in accordance with the recorded information signal. Solved by the device.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the optical information recording/reproducing apparatus of this invention will be described in detail based on an Example.

FIG. 1 is a schematic block diagram of an optical information recording/reproducing apparatus according to the present invention. In the figure, the internal structure of the optical head 19 is the same as that of the optical head shown in FIG. However, the photodetector 8.9 and its optical signal processing circuit are not shown because they are not directly related to the present invention. In addition, in the figure, 31 is an optical card,
18 is a driving means for moving the card in the R direction. Second
The pulse diagrams in FIGS. (4) to (D) show the waveforms of signals at positions (4) to (b) in the block diagram of FIG. 1. Hereinafter, clock signal reproduction will be described with reference to FIGS. 1 and 2.

The information to be written is modulated by the modulation circuit 16, and the power of the light source 1 is, for example, the second
There are two intensities, KPL and PH, as shown in Figure (4). A when information is 0? The reason why it is not a qua-O is because it is necessary for regenerating the clock.

Now, when the clock track is scanned with the power of the light source 1 set to a constant value PL, the output from the photodetector 7 is the preamplifier 10.
As shown by the broken line in Fig. 2 (B) at the point of complete passage π,
If the Q of the light source is set to a constant value PH, the waveform will be as shown by the dashed line in FIG. 2(B). If the clock track is scanned with the light from the light source 1 modulated by the recorded information as shown in FIG. 2(A), the waveform will be as shown by the thick solid line in FIG. 2(B). When the arm of the light source is changing from PH to PL in this way, the amplitude of the output waveform is not constant.

Therefore, in the present invention, the amplification amplifier 11 is configured to take two values, the amplification degree A and the amplification degree (PL/P□)A. /PH)A. In FIG. 1, signal S is an amplification direct switching signal sent from modulation circuit 16 to amplification amplifier 11. In FIG. By doing this, the amplitude of the output waveform of the amplification amplifier 11 remains constant, and when this is passed through the bandpass filter 12, it becomes a waveform as shown in FIG. 2(C)K. This waveform zero cross comparator 1
3, converts it into a binary V-pel, and then passes it through a PLL circuit to obtain a stable clock signal as shown in FIG. 2 (b).

In addition, as shown in Figure 2 C), when switching to direct amplification,
Switching noise N (input) normally cannot be suppressed completely with a band-pass filter and becomes a problem. To solve this problem, the phase of the recording information signal is shifted by 1/2 clock unit from the rising and falling timing of the clock by the phase converter 15 (in other words, when the signal is a sine wave, π
The influence of noise can also be prevented by delaying the time at which noise enters from the zero-crossing time (by shifting the phase by /2).

FIG. 3 shows that the phase of the recording information signal is shifted by 172 clock units on the recording medium 31. FIG. 3(4) shows a conventional method in which the rising edge 9 of the recording bit 35 and the rising edge 9 of the clock bit 32 coincide. FIG. 3B shows an improved method, in which the rising edge of the recording bit 35 and the rising edge of the clock bit 32 do not coincide, making it possible to prevent the influence of noise.

In the above embodiment, a clock track provided close to a recording area was described as an example of information bits pre-recorded on a recording medium. It is clear that the method of the invention can also be applied to clock signal recovery of information bits that are

〔Effect of the invention〕

As explained above, according to the optical information recording/reproducing apparatus of the present invention, a stable clock signal can be reproduced by switching the amplification factor of the amplifier according to the optical power of the recording modulation signal. It has become possible.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an optical information recording/reproducing apparatus according to the present invention. FIG. 2 is a diagram showing waveforms in each part of the apparatus of the present invention, and FIG. 3 is a diagram showing differences from the conventional method on a recording medium. Figure 4 (6) is a schematic diagram of the optical card), Figure 4 (B)
FIG. 2 is a diagram showing how recording is performed on an optical card. FIG. 5 is a schematic perspective view of the optical head. 31: Optical card, 32: Clock track, 35: Recording bit.

Claims (1)

[Claims] (1) Using one of multiple light beams split from the same light source to reproduce information pits previously recorded on a recording medium, use another light beam to record information on a track or An optical information recording and reproducing apparatus for reproducing information, characterized by comprising means for changing the amplitude of a reproduced signal from a clock in response to modulation of a recorded information signal.