JPH03113845A - Optical card - Google Patents

Abstract

PURPOSE:To obtain an always adequate focus error signal even during seek action by arranging and constituting the track number patterns and recognition patterns of an ID part in such a manner that the area of the incident reflected light on a photodetector for detecting the focus error is smaller than the area of the photodetecting surface of the photodetector. CONSTITUTION:The ID part 3a consists of cells 7-1 to 7-16, the recognition pattern regions 8 and the track number pattern regions 9. The track number patterns and recognition patterns are so arranged and constituted that the area of the reflected light from the regions 7-1, 7-16 of the reflectivity of the ID part 3a entering the photodetector to detect the focus error signal is smaller than the area of the photodetecting surface of the photodetector. The always adequate focus error signal is obtd. in this way even during the seek action.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an optical card.

[Conventional technology]

Conventionally, a card-shaped optical information recording carrier as shown in FIG. 4 has been proposed. In such an optical card 1, information is recorded as the level of reflectance and is optically reproduced. This information is recorded or reproduced in units called tracks, and a plurality of linear strip-shaped tracks 2 are arranged in parallel to constitute one optical card 1.

In the optical card 1 shown in FIG. 4, in order to search for a target track, a track number pattern of the track 2 and a specific recognition pattern common to each track for recognizing the track number pattern are provided at both ends of each track 2. Recorded ID section 3a.

3b, 3c, and data sections 4a, 4b for recording these IO detailed data, as well as a card drive pattern 5 for controlling card drive.

FIG. 5 shows the configuration of the track 2 shown in FIG. 4. In FIG. 5, each track 2 has eight cells 7-1 to 7-8, 7-9 on both sides of the lock pattern 6.
7-16, and the ID section 3a has a cell 7-16.
The recognition pattern common to areas 8 from 5 to 7-12 is cell 7.
A track number pattern indicating the track number is recorded in area 9 of -1 to 7-4 and 7-13 to 7-16. Note that each cell has a width of, for example, ID μm, and the track number pattern is recorded in, for example, a binary code.

An optical card having such an ID section is, for example,
It is also disclosed in Japanese Patent No. 3-145669.

In the recording and/or reproducing apparatus using the optical card 1 described above, the optical card 1 is placed on the frame 15 as shown in FIG. 6A and FIG. It is moved in the track direction via 17a and 17b. Further, an optical pickup 18 that performs recording/reproduction on/from the optical card 1 is disposed facing the optical card 1, and is driven by a seek motor 19 via a screw 20 in the theta direction perpendicular to the track. It has become.

The optical pickup 18 has the configuration shown in FIGS. 7 and 8, for example. In addition, Figure 7 is Figure 6B.
FIG. 8 is a view seen from the same direction as FIG. 6A. In Figure 7 and Figure 8,
Light from a light emitting diode (LED) 21 passes through a collimator lens 22, a half mirror 23, a mirror 24, and an objective lens 25, and is projected onto the optical card 1 to spot illuminate the track. 24, a half mirror 23, and a lens 26, the pattern on the card is magnified by, for example, 2.5 times and is received by a photodetector 27.

The objective lens 25 is directed toward its front axis (focus direction) F
and is supported by the base of an optical head (not shown) via four wires 28 so as to be displaceable in the track width direction (tracking direction) T of the optical card 1, and is supported in the focus direction F and It is designed to be driven in the tracking direction T.

Further, the LBD 21 is at the focal position f of the collimator lens 22.
In this conventional example, the focus position f is shifted from 0. When the optical card 1 is positioned at the object-side focus position of the objective lens 25, the LBD
The illumination light from 1 is converged in front of the optical card 1 to illuminate the optical card 1 in a defocused state. In this way, the illuminance distribution of the illumination light on the optical card 1 will become as shown by the solid line in FIG. 9 in the focused state, and as shown in FIG. 9 in the state where the optical card 1 is closer to the objective lens side. The broken line indicates that the 9th
This is shown by the dashed line in the figure. In this way, the illuminance distribution of the illumination light on the optical card 1 changes depending on the distance between the objective lens 25 and the optical card l, but as is clear from FIG. An unchanging part on the ring where the illuminance hardly changes even if the distance between the objective lens 25 and the optical card 1 changes (indicated by the reference numeral 29 in FIG. 9)
occurs, and changes in illuminance due to changes in the focal state of the objective lens 25 are opposite between the inside and outside of this unchanged portion 29. That is, when the optical card 1 approaches the objective lens side rather than the focal position of the objective lens 25, the illuminance increases on the inside of the unchanged portion 29 compared to when in focus, but decreases on the outside, and vice versa. When the optical card 1 moves away from the focal point of the objective lens 25, the illuminance decreases inside the unchanged portion 29 compared to when it is in focus, but increases outside it. In this conventional example, the tracks of the optical card 1 are effectively illuminated inside the unchanged portion 29, and the above-mentioned change in illuminance distribution between the inside and outside of the unchanged portion 29 is utilized. The focus error signal is detected.

FIG. ID shows the configuration of an example of the photodetector 27 shown in FIG. An image of 2.5 times the size of the pattern on the optical card is projected on the photodetector 27, and the image is, for example, 12 μm x 12 μm so that 16 pieces of data in the width direction on each track 2 can be read simultaneously. Satte 16
Light receiving areas 41-1 to 41-16 for reading data are provided. Further, across each track 2, ID number of clock generation light receiving areas 42-1 to 42-ID are provided in the track direction at a pitch of 172 of the clock pattern image so as to receive an image of 602.5 times the clock pattern. 6 in the track width direction so as to receive light from both edge portions of the clock pattern image in the track width direction.
Four pairs of servo light-receiving areas 43-1 to 43-8 are provided facing each other and spaced apart from each other with a size of 7 μm. Note that the light receiving areas 41-1 to 41-16 for data reading, the light receiving areas 42-1 to 42-ID for clock generation, and the light receiving areas 43-5 to 43-8 for servo use L which is irradiated onto the optical card 1.
The servo light receiving areas 43-1 to 43-4 are arranged to correspond to the outside 1 of the unchanged portion 29 of the illumination light of the BD 21.

In this way, in this conventional example, the servo light receiving area 43
A focus error signal is obtained by determining the difference between the total amount of light received by the servo light receiving areas 43-5 to 43-8.

In addition, the total amount of light received by the servo light receiving area 43-5.43-7 and the servo light receiving area 43-6.43-8
A tracking error signal is obtained by calculating the difference between the total amount of light received at While performing focus servo using this focus error signal, the optical pickup 18 is moved in the track width direction, and the ID section 3a,
3b or 3C, and when a recognition pattern is detected based on the tracking error signal and the output of the data reading light receiving areas 41-1 to 41-16, the track number pattern is read to search for a desired track. I have to.

In addition, when reading data on the searched track 2, the optical card 1 is moved in the track direction while performing focus and tracking servo based on the focus and tracking error signals, and the outputs of the clock generation light receiving areas 42-1 to 421O are read. A clock signal is obtained based on this clock signal, and the outputs of the data reading light receiving areas 41-1 to 41-16 are taken in and data is reproduced in synchronization with this clock signal.

[Problem to be solved by the invention]

However, in the conventional optical card 1 described above,
Cells 7-1 to 74 and 7 in the ID section of each track
Since the track number pattern is recorded in area 9 from -13 to 7-16, the track number is, for example, 16.
(ID base), MSB in binary code
000ID000 LSB, and the relationship between the image of the ID portion pattern projected onto the photodetector 27 during the seek operation and each light receiving area of the photodetector 27 is as shown in FIG. In FIG. 11, assuming that the size of one cell of the card pattern is multiplied by 2.5 times by the optical system of the optical pickup 18, it becomes 25 μm when the cell width is ID μm. In this way, the servo light receiving area 4 of the photodetector 27
When all the ID part patterns projected on 3-1 to 43-8 have low reflectance, the servo light receiving areas 43-1 to 43-8
Since the amount of light received at 43-8 decreases, the change in the illuminance distribution between the inside and outside of the unchanged portion 29 of the illuminance distribution decreases, and as a result, the ratio of the focus error signal to noise decreases. There's a problem. In addition, when the amount of light received by the servo light receiving areas 43-1 to 43-8 decreases, the sensitivity of the focus error signal to the focus direction decreases, so the focus servo is likely to come off during the seek operation. There is a problem. This kind of problem is not limited to when the track number is 16, but also when the track number is 16.
A similar problem occurs when three or more 0'' (regions of low reflectance) occur in succession.

The present invention has been made in view of these conventional problems, and is designed to be appropriately configured so that a proper focus error signal can always be obtained even during a seek operation, and therefore a target track can be accurately searched. The purpose is to provide optical cards.

[Means and effects for solving the problem] In order to achieve the above object, the present invention has a plurality of tracks parallel to each other, and each track has a track number pattern representing a track number for identifying the track. , a specific recognition pattern common to each track for recognizing the track number pattern is formed with a region of low reflectance and a region of high reflectance in the track width direction, respectively.
In an optical card having an n section, the track number pattern and the fFEB identification pattern are determined by the area of the reflected light from the low reflectance region of the ID section that is incident on the light receiving element that detects the focus error signal. The elements are arranged and configured so that the area is smaller than the area of the light-receiving surface of the element.

〔Example〕

FIG. 1 shows the main parts of a first embodiment of the invention. This optical card 45 is constructed in the same manner as shown in FIG. -1.7-2.7-5.7-8.7-9.7
-12°7-15 and 7-16 are the recognition pattern area 8, cells 7-1 and 7-16 are binary code 0'' (area of low reflectance), and other cells are “1”.
(area of high reflectance) is recorded, and the remaining cells 7-3.7-4.7-6, 7-7,
7-ID゜7-11.7-13 and 7-14 are set as area 9 of the track number pattern, and track numbers are recorded in these eight cells in binary code. In addition, in this embodiment, the track number pattern is wiped when it is read so that the LSB (least significant bit) of the track number is located at the center of the illumination light.In other words, as shown in FIG. Since the amount of illumination light on the card is greatest at the center and decreases toward both ends, reading errors are likely to occur at both ends where the amount of illumination light is small.

Therefore, in this embodiment, the MSB (most significant bit), where the track number changes greatly, is placed at the end of the illumination light, and the LSB, where the track number changes little, is placed at the center of the illumination light. In this way, the least significant digit of the track number can always be read effectively, and erroneous seeking to adjacent tracks can be reliably prevented.

According to this example, the track number is MSB 0000
0000 LSB to MSB 11111111 [,
Even if it changes to SB, there will be up to two consecutive cells with low reflectance during the seek operation in the ID section, but three or more cells will not consecutively occur.

Therefore, as in the conventional example, the width of the cell is
The dimension in the track width direction of the servo light-receiving area that forms a pair of μm1 photodetectors is 67 μm.If the magnification of the optical system of the 1-light pickup is 2.5 times, the continuous low reflectivity projected onto the servo light-receiving area is 67 μm. The maximum area is 5 in the track width direction.
0 μm (2X ID μm You can do it by doing this.

Next, recording/recording when using the optical card 45 of this embodiment is as follows.
A seek operation by the playback device will be explained. The recording/reproducing device, its optical pickup, and the photodetector constituting the optical pickup are shown in FIGS. 6A and B, FIG. 7,
The ones shown in Fig. 8 and Fig. ID are used.

The outputs of the servo light receiving areas 43-1 to 43-8 of the photodetector 27 are supplied to an error detection circuit shown in FIG. 2 to obtain a focus error signal and a tracking error signal. This error detection circuit is composed of addition circuits 51 to 54 and 57 to 59 and subtraction circuits 55, 56 and 60, and adds the output of the servo light receiving area 43-1 and the output of the servo light receiving area 43 to 2. The outputs of the servo light receiving area 43-3 and the outputs of the servo light receiving area 43-4 are added together in the adding circuit 51. Further, the output of the servo light receiving area 43-5 and the output of the servo light receiving area 43-6 are added in an adder circuit 53, and the output of the servo light receiving area 43-7 and the output of the servo light receiving area 43-6 are added together.
The outputs of 8 are added by an adder circuit 54.

The outputs of the adder circuit 51 and the adder circuit 53 are sent to the subtracter circuit 55.
The outputs of the adder circuits 52 and 54 are subtracted by the subtracter circuit 56, and the outputs of the adder circuits 52 and 54 are subtracted by the subtracter circuits 55 and 56.
An adder circuit 57 adds the outputs of the FB to obtain a focus error signal (FB).

Further, the output of the servo light receiving area 43-5 and the output of the servo light receiving area 43-7 are added in an adder circuit 58, and the output of the servo light receiving area 43-6 and the output of the servo light receiving area 4 are added.
The outputs of 3-8 are added by an adder circuit 59, and the outputs of these adder circuits 58 and 59 are subtracted by a subtracter circuit 60 to obtain a tracking error signal (TE).

In the seek operation, the optical pickup 18 is moved in the theta direction perpendicular to the track via the screw 20 by the seek motor 19 shown in FIG.
Scan section 3a, 3b or 3C. These ID parts 3
Since the recognition pattern $ and the track number pattern are written in a, 3b and 3C as shown in FIG. At the time when the recognition pattern is detected, that is, the light receiving area for data reading 41-2.41-5.41-8°41-9.41
When the outputs of -12 and 41-15 are "1" and the outputs of 41-1 and 41-16 are 1 (O11), the remaining light receiving areas 41-3.41-4.41 for data reading are
-6.41-7.41-ID. 41-11.41-13
Then, the track number is read based on the output of 41-14, and if the desired track is found, the head motor 19 is stopped, and the tracking servo is closed loop, thereby completing the seek operation to the target track. Also,
When reading data on the sought track, the optical card 45 is moved in the track direction while performing focus and tracking servo based on focus and tracking error signals, and data is read based on the outputs of the clock generation light receiving areas 42-1 to 42-ID. A clock signal is obtained, and in synchronization with this clock signal, the outputs of the data reading light receiving areas 41-1 to 4116 are taken in and the data is reproduced.

FIG. 3 shows the main part of a second embodiment of the invention. This optical card 61 is also constructed in the same manner as shown in FIG. 4, but in this embodiment, among the sequential cells constituting each track 2 in each ID section 3a, 3b, 3c, cells 7-1.
7-3.7-5.7-8.7-9.7-12.7-14
and 7-16 as area 8 of the recognition pattern, cell 7
-16 is '0', the cell of that number is '1', and the remaining cells 7-2.7-
4.7-6°7-7,7-ID. 7-11.7-13 and 7-15 as area 9 of the track number pattern,
A track number pattern is recorded in the cells of these areas 9 so that the lower bit is located at the center of the illumination light when reading the track number. Therefore, in this embodiment as well, there are no more than three consecutive If OIf cells in the In section, so it is possible to obtain the same effect as in the first embodiment.

Note that this invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, in the above-mentioned embodiments, the ID section is configured so that three or more cells with a low reflectance of "0" do not occur in a row, but the reflection from the low reflectance area that enters the light receiving element for focus error detection. If the area of light is smaller than the area of the light-receiving surface of the light-receiving element, it is also possible to configure three or more cells with low reflectance in series.

〔Effect of the invention〕

As described above, according to the present invention, the ID section is configured such that the area of the reflected light from the low reflectance region that enters the focus error detection light receiving element is smaller than the area of the light receiving surface of the light receiving element. Since the track number pattern and the recognition pattern are arranged, it is possible to always obtain a proper focus error signal even during a seek operation, and therefore it is possible to accurately search for a target track.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main parts of the first embodiment, FIG. 2 is a diagram showing the configuration of an example of an error detection circuit when using the optical card shown in FIG. 1, and FIG.
Figure 4 is a diagram showing the main part of the embodiment, Figure 4 is a diagram showing an overview of the optical card, Figure 5 is a diagram showing the configuration of a conventional In part, and Figures 6 A and B are an example of a recording/reproducing device. Figures 7 and 8 are diagrams showing an example of the optical pickup shown in Figure 6, Figure 9 is a diagram showing changes in the illuminance distribution of illumination light on the optical card, and ID diagram is Figure 7. A configuration diagram of an example of a photodetector shown in Fig. 1.
FIG. 1 is a diagram showing the positional relationship between the photodetector and the ID section shown in FIG. 7. 2...Trucks 3a, 3b, 3c...
・ID section 6...Clock pattern 7-1 to 7-16
...Cell 8...Recognition pattern area 9...Track number pattern area 27...Photodetector 41-1 to 41-16...Light receiving area for data reading 42-1 to 42-ID...・Clock generation light receiving area 4
3-1 to 43-- Servo light receiving area 45° 61... Optical card same

Claims (1)

[Claims] 1. It has a plurality of tracks parallel to each other, each track has a track number pattern representing a track number for identifying the track, and a common track number pattern for each track for recognizing the track number pattern. a specific recognition pattern,
In an optical card having an ID section formed with a region of low reflectance and a region of high reflectance in the track width direction, the track number pattern and the recognition pattern are incident on a light receiving element that detects a focus error signal. 1. An optical card characterized in that the optical card is arranged such that an area of reflected light from a region of low reflectance is smaller than an area of a light-receiving surface of the light-receiving element.