JPS6262436A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a clock signal having a good S/N ratio and to attain the accurate recording and reproducing of information by providing an optical detector that detects the clock signal as the one divided into two pieces and standing in line in the longitudinal direction of a clock track and taking the difference between two outputs. CONSTITUTION:When the information is recorded on a recording area 4, spots S1-S3 are irradiated on each of a clock track 21, the recording area 4 and a tracking track 31. These spot are scanned in arrow head direction (a) by the movement of an optical card 1 and reflecting light from the spot S1 is made incident on an optical detector 17, regenerating the clock signal. Therefore, the scanning of a clock part by the spot S1 causes the movement of the spot on a corresponding optical detector 17 in the longitudinal direction of the clock track and as a result, the generation of a difference in light intensity between the light made incident on A and B, and C and C, and the clock signal having a good contract by taking the difference of the outputs between A and B and C and D can be obtained. A recording is performed on the recording area 41 based upon the clock signal, a tracking signal and a focusing signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording/reproducing device, and more particularly to a device used for an optical information recording medium provided with a track for obtaining a tracking signal and a clock signal. .

In the present invention, an optical information recording/reproducing device refers to a device for storing information on an optical information recording medium as described above, a device for reproducing information recorded on an optical information recording medium, and a device for performing both recording and reproduction. Show the device.

[Prior Art] Conventionally, optical information recording media that record information using light and read out the recorded information have been disk-shaped,
Various types such as card-shaped, tape-shaped, etc. are known. Among these, card-shaped optical information recording media (hereinafter referred to as optical cards) are expected to be in great demand as small, lightweight, easy-to-carry, large-storage-capacity media6. The optical card described in item 1-1 creates an optically detectable recording pit array (information truck)
Information is recorded as .

At this time, in order to accurately record information without causing problems such as crossing of information tracks, it is necessary to control the irradiation position of the light beam in a direction perpendicular to the scanning direction (W (auto tracking, hereinafter referred to as AT). It was necessary to do so. Also,
In order to compensate for variations in scanning speed, it was also necessary to obtain a clock signal.

Therefore, the applicant of the present application is Drexla Technology Co., Ltd.
xler Technology Corpora
According to a technical disclosure received from Japan, an optical card has been proposed in which a track for obtaining a tracking signal and a clock signal is formed in advance on the card. A first example of such an optical card is shown in FIG.

FIG. 10(A) is a schematic plan view of the optical card.
1 has a recording area 44 l+ 442 1-m---
On one side, a clock track 421, 422 is formed in the shape of an intermittent broken line.

Tracking tracks 431, 432-433+-1111 are formed on the other side, respectively. Here, the tracking track 43. ．．
-----One is made into a continuous line.

FIG. 1θ (B) shows a partially enlarged view of the recording surface of the optical card 41. When recording information on the optical card 41, three beams are emitted from the optical head, and each beam is made into a minute beam. Spora) The light is focused as S+, S2, and S3. These spots are scanned in the direction of arrow a by the relative movement of the optical card and the optical head, and are scanned in the recording area 4.
41, information is recorded like a recording pit 45 by a spot S2 in the middle. Further, the reflected light from the spora 33 is guided to a detection means in the optical head, and a tracking signal is detected using a well-known method such as the so-called push-pull method. Based on this tracking signal, spots St,
These spots are moved together in a direction (b direction) perpendicular to the scanning direction (a direction) of 32153, and controlled so that the spora S+ always accurately traces the clock track 421. Therefore, the recording pits 45 are accurately formed along the clock track 421, 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 of the spot 31 and used as a clock for the recording signal. Furthermore, information is reproduced in the same manner.

However, in the above-mentioned optical card, the clock signal is detected using the change in the amount of light caused by the diffraction and scattering of the light beam on the clock track on the card. If the edge portion of the clock pattern is almost the same as the area and the change in the edge portion of the clock pattern is not steep, there is a problem that the S/N ratio of the clock signal is poor and a good lock signal cannot be obtained.

An example of an optical information recording/reproducing device that solves this problem is proposed in the above-mentioned technical disclosure. This is shown in FIGS. 11 and 12.

Figure ti shows the above-mentioned spora) S+ on the card surface.

s2 and s3 correspond to photodetectors 101, 102, respectively.
103 and spots S+', S2', 33'
This shows the state in which a is formed. In this example, spot S
Focusing on the fact that the corresponding spot s+' moves in the track direction when the clock signal 1 crosses the clock track, the edge of the photodetector lO1 is set using a parallel plate glass inserted in advance at the position of the spora) 31' in the middle of the optical path. A signal is generated only when the spot moves into the photodetector 101. However, this method requires shifting only S+' out of the three spots, which requires a member such as parallel flat glass, and in order to insert parallel flat glass, the three spots must be spaced apart. Therefore, it is not practical from the viewpoint of downsizing the device.

FIG. 12 shows an attempt to obtain the same effect as the example of FIG. 11 by shifting the photodetector 101 by a certain amount in advance instead of shifting the spot S+'.

This method solves the above problems, but since the positional relationship of the photodetectors is fixed, if the spot size changes, the S/N ratio of the signal changes, and when assembling the device. The problem is that adjustment is difficult.

In addition, in the method described above, the role of the photodetector is fixed, and two types of tracks are used for each information track: a clock track for obtaining a clock signal and a tracking track for obtaining a tracking signal. There was a need to form the data on the card, which placed a limit on the recording capacity per area.

[Means for solving the problem] The above problem lies in the device for recording or reproducing information on an optical information recording medium in which tracking tracks and clock tracks are arranged alternately and a recording area is provided between each track. means for forming three beam spots on the optical information recording medium and scanning the recording area with a first beam spot to record or reproduce information; and second and third beams. means for scanning the tracking track to detect a tracking signal in one of the spots; means for detecting a clock signal from the clock track in the remaining spots; and means for detecting a clock signal from the clock track in the remaining spots;
2. In an optical information recording and reproducing apparatus having means for switching between the means for detecting the tracking signal and the means for detecting the clock signal according to the arrangement of the king tracks, the means for detecting the clock signal is arranged according to the length of the clock track. This problem is solved by the optical information recording/reproducing device of the present invention, which has two detection areas arranged in a horizontal direction, and detects a clock signal based on the output of one of the detection areas or the difference signal between the two outputs. Here, the length direction of the clock track indicates the scanning direction of the beam spot.

[Example 1 Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic plan view of an optical card using the device of the invention.

In FIG. 2, the optical card 1 has clock tracks 2+, 22.23, ----1 formed in the form of intermittent broken lines with clock signals recorded in advance, and tracking tracks formed in the form of a continuous line. Track 31. 32, ---
-- are arranged alternately at equal intervals. And a recording area 4+-4 for recording information between each track.
2*43*--1-- is provided. That is,
The optical card 1 has a recording area entirely between the clock track and the tracking track.

3, 4, and 4 are diagrams for explaining the structure of an embodiment of the optical information recording/reproducing apparatus of the present invention, in which FIG. 3 is a perspective view and FIG. 4 is a side sectional view. A beam emitted from a light source 11 such as a semiconductor laser is collimated by a collimator lens 12 and divided into three beams by a diffraction grating 13. These beams are imaged by an objective lens 14 onto an optical card l as shown in FIG.
2, form S3. Here, the optical card 1 is moved in the direction of arrow R by a driving means (not shown), and is scanned by the spot in the direction in which the tracking track and the clock track extend.

Spot) S+, 32. The reflected light from 33 passes through the objective lens again, is reflected by the mirror 15, and is directed to the photodetector 17.18.1 placed in the focal plane by the condenser lens 16.
9 respectively. These photodetectors are arranged side by side in the Z direction shown in the figure, as shown in FIG. Further, the light receiving surface of the photodetector 17.19 is divided into four parts as A, B, C, and I).

Next, the operation of recording information on an optical card using the above-mentioned apparatus will be explained with reference to FIGS. 5 to 7. FIG. 5 shows a partially enlarged view of the recording surface of the optical card. First, when recording information in the recording area 41, spots Sl, S2,
S3 is applied to the clock track 21, recording area 41, and tracking track 3I, respectively. These spots are scanned in the direction of the arrow a by the movement of the optical card l as described above. The reflected light from Spora) S+ enters the aforementioned photodetector 17, and a clock signal is reproduced. That is, the light-receiving surface of the photodetector is arranged at A, B, C, and D with respect to the Z-axis direction corresponding to the direction in which the clock tracks are arranged as shown in FIG.
It is divided into Therefore, when the spot S1 scans the clock section, the spot on the corresponding photodetector 17 moves in the length direction of the clock track, resulting in A, B
There is a difference in the intensity of light incident on C and D, and these A and B
By taking the difference between the outputs of C and D, a clock signal with good contrast can be obtained. Recording is performed in the recording area 41 based on this clock signal, a tracking signal, and a focusing signal, which will be described later.

FIG. 6 is a diagram showing the output from the photodetector.

In the figure, the solid line indicates the difference between the outputs of A, B and C, D, and the broken line indicates the output of a single conventional photodetector or the difference between the outputs of A, B and C.
, D. When one photodetector is used, if the difference between the reflectance of the clock part of the clock track and the reflectance of the peripheral part is small, an output with good contrast cannot be obtained. Even if a method such as the conventional example shown in FIG. 11 or 12 is used, sufficient contrast cannot be obtained with the output from one photodetector.As already explained, when the spot crosses the clock section, the photodetector Since lateral movement of the spot occurs on the surface, in order to detect this, it is better to take the difference between the outputs of two photodetectors than to use one photodetector, as is well known from autofocus signal detection technology. The contrast is also good, and the detection sensitivity is also good.

Next, the reflected light from the spora) S3 enters a photodetector 19, and a tracking signal is detected by a so-called push-pull method. That is, the light-receiving surface of the photodetector is A, C, and B with respect to the y-axis direction corresponding to the length direction of the tracking track as shown in FIG.

It is divided into D. Therefore, if the spora) 33 deviates from the tracking track 3I, a difference will occur in the intensity of light incident on A, C and B, D, and a tracking signal can be obtained by comparing the signals from these light receiving surfaces. . Based on this tracking signal, an unillustrated tracking means (for example, a means for moving the objective lens 14 in the Z direction in FIG. 3) moves the spora) S+, S
2. S3 is integrally moved in the direction perpendicular to the scanning direction (direction b), and AT is performed. Then, recording pits 5 are accurately recorded in the recording area 41 along the tracking track 31 by the spot S2.

Further, in the above recording, the photodetector 19 detects a focusing signal for controlling # (autofocusing, hereinafter referred to as AF) so that the spot is accurately focused on the recording surface of the optical card, at the same time as AT. This detection principle is explained in the seventh
This is explained briefly with a diagram.

In FIG. 7, members common to those in FIG. 4 are denoted by the same reference numerals, and detailed explanations will be omitted. As shown in the figure, the incident light 20 forming S3 is obliquely incident on the recording surface 21 of the optical card, and the reflected light 22 is reflected when the subo 2 is accurately focused on the recording surface. In this case, the light enters the mirror 15 parallel to the incident light 20 and is guided to the detection surface 23 . However, if the recording plane is shifted vertically at points 21' and 21'' with respect to the focal position, the reflected light will be non-parallel to the incident light at points 22' and 22'', respectively, and the irradiation position will be shifted on the detection plane 23. moves in the y direction. Therefore, a focusing signal can be obtained by detecting such a change in the light intensity distribution in the y direction as a difference in output between the light receiving surfaces A, B and C9D of the photodetector 19 placed on the detection surface 23. According to this focusing signal, the objective lens 14 is moved in the optical axis direction to perform AF.

Next, when recording information in the recording area 42, by moving the optical system and the optical card relatively in the Z direction as shown in FIG.
,S? , S3 are the tracking tracks 31, respectively.
, recording area 42. The clock track 22 is arranged to scan. Then, while performing AT and AF by receiving the reflected light from the spot S+ with the photodetector 17,
3 regenerates the clock signal from the photodetector 19;
Information is recorded at spot S2.

In this way, in one aspect of the present invention, two spots are used exclusively for reading the tracking track and the clock track, respectively, and information is recorded in all recording areas by switching the operations as described above. .

Reproduction of information recorded in this manner is also performed in the same manner as during recording, using the above-described apparatus. On the recording surface of the optical card, there are clock tracks 2+ + 22 as shown in Figure 8.
, +++- and tracking track 31,--
--Information track 25 consisting of a recording bit string between
．． ．． 252, ----1 is formed. First, information track 25! When reading the information of spot S
l, S2. 33, the clock track 21, the information track 251, and the tracking track 3! arrow a
The information recorded on the information track 251 is read by the photodetector 18 while scanning in the direction, reproducing the clock signal with the photodetector 17, and performing AT and AF with the photodetector 19.

Also, in the playback of Information Tra-7ri 252, Spot S+
, S2 and S3 respectively tracking track 3I,
The information track 252 and the clock track 22 are scanned in the direction of arrow a, the photodetector 19 reproduces the clock signal, and the photodetector 17 performs AT and AF while the photodetector 18 records the clock signal on the information track 252. Read information. By switching operations like this, information recorded in any area of the optical card can be reproduced.

FIG. 9 is a block diagram showing a specific example of a signal processing system from the photodetectors 17, 18, and 19 described above. Here, an example is shown in which an address signal for each track is recorded in advance in the recording area. In the figure, 50 is a separation circuit that separates the address signal Ad and the reproduced signal RF from the read signal, 51 is a control circuit that controls opening and closing of switches SW+ and SW2 according to the address signal Ad, 52, 53, 54,
55.58, 59, 60.61 are addition amplifiers, 56°5
7, 62, and 63 are subtraction amplifiers, and C1 to C9 are terminals. In FIG. 5 described above, when recording is performed in the recording area 4I, the address signal Ad is first read out by the photodetector 18, and the arrangement of the recording area to be scanned and the tracking track is determined by this address signal Ad (at()). It is determined which side of the recording area the rough king track is located on, and the control circuit 51 moves the switch SW+ to the terminal C2 side.
Connect the switch SW2 to the terminal C8 side. Therefore, the difference between the sum of the outputs of the light receiving surfaces A and H of the photodetector 17 and the sum of the outputs of C and D of the photodetector 17 is obtained as a clock signal CL through the addition amplifiers 53 and 54 and the subtraction amplifier 56 at the terminal CI. -Ill record by S2 as a reference signal through a processing circuit. Additionally, terminal C6 has an adding amplifier 5.
9.60 and the subtraction amplifier 63 to the light receiving surface of the photodetector 19, the difference between the sum of the outputs of C and the sum of the outputs of B and D is obtained as a tracking signal AT. This signal AT is supplied to a tracking servo circuit (not shown) from a terminal C6. Further, the difference between the sum of the outputs of the light receiving surfaces A and H of the photodetector 19 and the sum of the outputs of C and D of the photodetector 19 is obtained as a focusing signal AF through the addition amplifiers 58 and 61 and the subtraction amplifier 62 at the terminal C9. This signal AF is supplied from a terminal C9 to a focus servo circuit (not shown).

When recording in the recording area 42, the address signal Ad
The control circuit 51 changes the switch SW +
is connected to the terminal C3 side, and switch SW2 is connected to the terminal CI side. Similarly, a tracking signal AT is obtained at the terminal CI, a clock signal CL is obtained at the terminal C6, and a focusing signal AF is obtained at the terminal C4.

Also, when reproducing information as shown in FIG. 8, the switching operation is performed exactly the same as in the case of recording. here,
The reproduced signal RF read out by the photodetector 18 is separated from the address signal Ad by a separation circuit and taken out from the terminal C5.

In this embodiment, the focusing signal and the clock signal are taken out from separate terminals, but since these two signals are exactly the same, it is also possible to use a common terminal.

Also, the above explanation was about taking the difference between the outputs of two detectors in the length direction of the clock track, but since it only detects the movement of the spot, the output of either one of the two detectors is Of course, it is also possible to obtain a clock signal using only

The present invention can be applied not only to the embodiments described above, but also to various optical cards having clock tracks.

For example, switching by the address signal in Fig. 9,
Applications such as determining whether each photodetector is a tracking track or a clock track and switching between them are also possible.

Furthermore, the methods for detecting tracking signals and focusing signals are not limited to those in the embodiments, and any known method may be used. Furthermore, the focusing signal may be detected by a photodetector at the spot where recording and reproduction is performed. Here, the focusing signal may be detected by the method described in the embodiment or by other methods such as the so-called astigmatism method. However, in this case, the other two photodetectors can be two-split sensors that only detect clock signals or tracking signals.

Furthermore, although the present invention has been explained using a clock track that periodically generates a lock signal as an example, the method of the present invention is also effective when reproducing information from a track that includes general information such as a track number. is clear from the above explanation.

Furthermore, the present invention is applicable not only to devices for recording and reproducing as described above, but also to recording-only devices. It can also be applied to C storage and playback-only devices.

[Effects of the Invention] As explained in detail above, the optical information reproducing device of the present invention uses a two-part photodetector that detects a clock signal as a two-part photodetector arranged in the length direction of the clock track. By taking the difference between the outputs, a clock signal with a good S/N ratio can be obtained, which has the effect of enabling accurate recording and reproduction of information.

[Brief explanation of the drawing]

1 to 9 are diagrams for explaining the present invention in detail. 10 to 12 are diagrams for explaining information recording and reproducing in a conventional optical information recording and reproducing device. ... Diffraction grating 14 - Φ ... Objective lens 15 ... Two lenses 16 ... Condensing lens 17, 18, 19 ... Photodetector Sl, S2 . 33 ... Beam Spot Agent Patent Attorney Yohei Yamashita Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 11 Figure 12

Claims (1)

[Claims] An apparatus for recording or reproducing information on an optical information recording medium in which tracking tracks and clock tracks are arranged alternately and has a recording area between each track,
means for forming three beam spots on the optical information recording medium and scanning the recording area with a first beam spot to record or reproduce information; and either a second or third beam spot. On the other hand, means for scanning the tracking track to detect a tracking signal, means for detecting a clock signal from the clock track in the remaining spots, and detecting the tracking signal according to the arrangement of the recording area and the tracking track. In the optical information recording/reproducing apparatus, the means for detecting the clock signal has two detection areas arranged in the length direction of the clock track, and An optical information recording/reproducing device characterized in that a clock signal is detected by the difference signal between one output or two outputs of a detection area.