JPH03194728A - Optical card - Google Patents

Abstract

PURPOSE:To allow the sure detection of a frame during reading of data and to exactly retrieve the information in the optical card by forming frame detecting marks in the positions near the center of the beam in the range irradiated with a light beam. CONSTITUTION:Frame synchronizing lines 10 are formed near the clock patterns 3 of the respective frames in order to obtain a frame synchronizing signal. Namely, the frame synchronizing lines 10 are disposed in the positions nearest the positions X where the light quantity distribution of the illuminating light is maximized. The frame detecting marks are formed near the center of the illuminating light where the irradiating light quantity is largest. The quantity of the light to be projected is, therefore, sufficiently large and the resolution is high in this way. The generation frequency of reading errors is consequently extremely decreased. The sure frame detection is executed in the reading opera tion of the data in this way and the information in the optical card is exactly retrieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical card as an optical information recording carrier.

[Conventional technology]

Conventionally, a card-shaped optical information recording carrier as shown in FIG. 7 has been proposed. In such an optical card 71, information is recorded as the level of reflectance and is optically reproduced. The optical card 71 includes a data recording area 72 formed by forming a plurality of tracks extending in the longitudinal direction of the card in parallel with the card width direction, and in this recording area 72, attributes of the track are written at both ends corresponding to each track. ID sections 73a and 73b are formed in which the TD sections 73a and 73b are recorded, and data is recorded in a data section 74 between these TD sections 73a and 73b.

FIG. 8 shows an example of the track format of the optical card 71. In this example, each track 75 is divided almost equally into 20 lines (numbered 1 to 20 at the bottom of the drawing), and the 10th line counting from number l is
A clock pattern 76 for clock generation, focus error detection, and tracking error detection is formed by equally spaced black patterns over the portion 73a, data portion 74, and ID portion 73b. Also, ID sections 73a and 73b
A common recognition pattern 77 that exists only in the inner number of each track 75 and does not exist across two tracks, and a pattern 78 indicating the track number.
is the provision.

Furthermore, in the data section 74, each track 75 is provided with frames 79 corresponding to the number of companies, and a frame number section 80 is formed between adjacent frames and between the ID sections 73a, 73b and the frame 79, and each frame number section 80 is formed here. A frame number pattern 81 for recognition is formed.

Furthermore, a black frame synchronization line 82 for obtaining a frame synchronization signal is formed on the 20th line in each frame. The frame synchronization signal corrects synchronization deviations caused by missing clock signals due to dust, scratches, etc. occurring in the clock pattern 76 on the card. Note that 83 indicates the irradiation range of the beam to be irradiated. For example, such an optical card was created in 1983.
Various disclosures have been made, including Publication No. 38369 [
[Problems to be Solved by the Invention] However, since the illumination light irradiated onto the card 71 in the above conventional example has an illuminance distribution as shown in FIG. The resolution is lower than that at the center due to the aberration of the condenser lens. Note that the solid line shows the focused state, the broken line shows the state where the condensing lens approaches the optical card position, and the dashed line shows the state where the condensing lens moves away. Therefore, there is a problem in that reading errors on the 20th frame synchronization line 82 are likely to occur, and therefore erroneous frame detection is likely to occur.

A conceivable way to solve the above problem is to add a correction additional bit to the frame synchronization line 82 to correct the error even if a reading error occurs. but,
There is a problem in that additional bits for correction cannot be added to the frame signal indicating the timing of reading data.

The present invention has been made by focusing on these conventional problems, and makes it possible to reliably detect frames while reading data, and therefore to accurately search for the target information in the optical card. The purpose is to provide a structured optical card.

[Means and Effects for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of mutually parallel tracks containing information including additional bits for error correction and frame detection marks for detecting frames, and a clock signal. By having a plurality of clock tracks to obtain clock signals, and by irradiating these with a beam from a light source using a collimator lens and a condensing lens in a state with an illuminance distribution,
In an optical card configured to record and reproduce information, a frame detection mark for detecting a frame in the track is placed within the range to which the light beam is irradiated, rather than at a position where information including additional bits for error correction is recorded. This was recorded near the center of the beam.

Since the frame detection mark is thus recorded at a position close to the center of the high-resolution illumination light, frame detection when reading data is ensured.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The outline of the optical card is constructed in the same manner as shown in FIG. 7 described as a conventional example.

FIG. 1 shows an embodiment of the track format of an optical card, in which 10 sections 1a and lb are formed at both ends, and data is recorded in a data section 2 between these 10 sections 1a and lb. Each track 4 is divided almost equally into 20 lines (portions numbered 1 to 20 at the bottom of the drawing), and the 10th line counting from number 1 contains the 10th section 1a, the data section 2, and the ID section 1b. In this way, a clock pattern 3 for clock generation, focus error detection, and tracking error detection is formed, which is composed of black patterns at equal intervals. Further, the 10 parts 1a and 1b are provided with a common recognition pattern 5 that exists only in each track 4 and does not exist across two tracks, and a pattern 6 that indicates the track number.

Further, in the data section 2, each track 4 is provided with a plurality of frames 7, and adjacent frame inter- and I
A frame number section 8 is formed between the D section 1a, lb and the frame 7, and a frame number pattern 9 for recognizing each frame is formed therein.

Next, in each frame, a black frame synchronization line 10 is formed near the clock pattern 3 in order to obtain a frame synchronization signal.

In other words, the frame synchronization line 10 is placed at the eighth line, that is, at the position closest to the position X where the light intensity distribution of illumination light as shown in FIG. 6 is at its maximum. This frame synchronization line 10 is formed as a black pattern within each frame 7, and is formed as a white pattern at a position indicating a boundary between frames. Note that 11 indicates the irradiation range of the beam to be irradiated. Next, the operation of reading the data section 2 will be explained. For example, as shown in FIG. 2-A and B, the optical card 12 is placed on a frame 13 in a playback device using the optical card 12.
2 to the rubber roller 15a by the card motor 14.

15b is rotated and moved in the track direction. Further, an optical pickup 16 that performs playback on the optical card 12 is arranged opposite to the optical card 12, and is driven in the theta direction perpendicular to the track via a screw 18 driven by a seek motor 17. It has become.

The one-light backup 16 has the configuration shown in FIGS. 3 and 4, for example. 3 is a view seen from the same direction as FIG. 2-B, and FIG. 4 is a view seen from the same direction as FIG. 4-A. Light from a light emitting diode (LED) 19 passes through a collimator lens 20, a half mirror 21, a mirror 22, and a condensing lens 23, and is projected onto the optical card 12 to spot illuminate the track. The pattern on the card is multiplied by n through the mirror 22, half mirror 21, and lens 24, and is received by the photodetector 25.

The condensing lens 23 is oriented in the front axis direction (focusing direction) F and in the track width direction (tracking direction) of the optical card 12.
It is supported on the base of an optical head (not shown) via four wires 26 so as to be able to be displaced in the direction T, and can be driven in the focus direction F and the tracking direction T by a known focus and tracking actuator (not shown). Further, the LED 19 is shifted from the focal position fO of the collimator lens 20, and in this embodiment is arranged slightly farther than the focal position fO. In this way, in a focused state where the optical card 12 is located at the object-side focal position of the condenser lens 23, the illumination light from the LED 19 is converged in front of the optical card 12, and the optical card 12 is illuminated in a defocused state. I'll do what I do.

In this way, the illuminance distribution of the illumination light on the optical card 12 becomes as shown by the solid line in FIG. On the other hand, when the object is far away, it becomes shown as a dashed line. In this way, the illuminance distribution of the illumination light on the optical card 12 changes depending on the distance between the condenser lens 23 and the optical card 12, but as is clear from FIG. Even if the distance between the condensing lens 23 and the optical card 12 changes, there is an unchanging part (indicated by reference numeral 27 in FIG. 6) on the ring where the illuminance hardly changes. The change in illuminance on the outside is opposite due to the change in the focal state of the condenser lens 23. That is, when the optical card 12 approaches the condensing lens 23 side rather than the focal position of the condensing lens 23, the unchanged portion 27
On the inside of the boundary, the illuminance increases compared to when in focus, while on the outside it decreases.Conversely, as the optical card 12 moves away from the focal position of the condenser lens 23, the illuminance inside the unchanged portion 27 decreases. While it decreases compared to when in focus, it increases outside.

In this way, the track of the optical card 12 is changed to the unchanged portion 2.
In addition, the focus error signal is detected by utilizing the change in the illuminance distribution between the inside and outside of the unchanged portion 27 as a boundary.

FIG. 5 shows the configuration of the photodetector 25.

An image whose size is n times the size of the pattern on the optical card is projected on the photodetector 25, and 17 data readings are performed so that 17 pieces of data in the width direction on each track 4 can be read simultaneously. Light receiving areas 28-1 to 28
-17 is the setting. In addition, in order to receive the image of the clock pattern 3 in each track 4, the clock pattern 3 is multiplied by n and ten clock generation light receiving areas 29-1 to 29-10 are provided in the track direction. Four pairs of servo light-receiving areas 30-1 to 30-8 are provided which are spaced apart and opposed to each other in the track width direction so as to receive images of both edge portions of the clock pattern 3 in the track width direction.

In addition, the light receiving areas 28-1 to 2B-17 for data reading
, clock generation light receiving areas 29-1 to 20-10, and
The servo light receiving areas 30-5 to 30-8 are arranged so as to correspond to the inside of the unchanged portion 27 of the illumination light of the LED 19 that is irradiated onto the optical card. 1 to 30-4 are arranged so as to correspond to the outside of the unchanged portion 27. In this way, in this embodiment, the total amount of light received by the servo light receiving areas 30-1 to 30-4 and the servo light receiving areas 30-5 to 30 to
A focus error signal is obtained by calculating the difference between the sum of the amounts of light received at 8 and 8. In addition, a track error signal can be detected by determining the difference between the total amount of light received by the servo light receiving area 30-5, 30-7 and the total amount of light received by the servo light receiving area 30-6, 30-8. It has gained. As described above, while performing focus and tracking servo using the focus and tracking error signals, the optical card 12 and the optical pickup 16 are moved relative to each other in the track direction to scan the data section 2 and the clock generation light receiving area 29-1. A clock signal is obtained based on the outputs of 29-10 to 29-10, and the outputs of the data reading light receiving areas 28-1 to 28-17 are taken in in synchronization with this clock signal.

On the 8th line of data captured in synchronization with the clock signal, frame detection marks are formed every m columns (the data area is a dark area, while the frame number area is a bright area). , the start of the next frame is recognized by detecting the frame detection mark when the m-column data is taken in. At the same time, by detecting the frame detection mark, synchronization errors caused by missing clock signals due to dust, scratches, etc. occurring in the clock pattern on the card are corrected. In addition, since the frame detection mark is formed near the center of the illumination light, the amount of light emitted is sufficiently large.
The resolution is also high. Therefore, the frequency of occurrence of reading errors is extremely low, and therefore, reliable frame position detection is easily possible.

- Data recorded in positions with a small amount of tip and low resolution (1st line and 20th line) are recorded from the 1st line to the 7th line, and from the 12th line to the 20th line using an interleave method (not shown). Data is arranged over the line, and additional bits for error correction are added. Therefore, even if a data reading error occurs, it can be corrected by the error correction.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and many changes and modifications are possible. For example, when data is recorded with a modulation rule in the track direction, and a data sequence that does not occur according to the modulation rule is used as a frame detection mark, the frame detection mark is set to the frame detection mark closest to the position where the illuminance distribution is maximum and the resolution is high. By arranging them in eight lines, it is possible to accurately detect the frame position.

〔Effect of the invention〕

As detailed above, according to the present invention, since the frame detection mark is formed near the center of the illumination light with a large amount of irradiation light, it is possible to easily detect frames reliably during data read operations on an optical card. can be provided.

[Brief explanation of drawings]

FIG. 1 shows the track format of the optical card according to the present invention, FIGS. 2-A and B are a plan view and a side view of the reading device, and FIGS. A and B are block diagrams showing the optical pickup section, Figure 5 is a block diagram of the photodetector shown in Figures 3 and 4, and Figure 6 is the illuminance distribution of illumination light on the optical card. FIG. 7 is a diagram showing an outline of an optical card. FIG. 8 is a diagram showing a track format of a conventional optical card. 1a...ID section 2...Data section 3...Clock track 4...Track 7...Frame 9...Frame number pattern 10...Frame synchronization line 11...Irradiation range 2nd Figure 3 Figure 4 Figure 8 Figure @7 Figure 8

Claims (1)

[Claims] 1. A plurality of mutually parallel tracks containing information including additional bits for error correction and frame detection marks for detecting frames, and a plurality of clock tracks for obtaining clock signals; In an optical card formed to record and reproduce information by irradiating a beam from a light source with a collimator lens and a condensing lens in a state with an illuminance distribution, a frame detection mark for detecting a frame in the track is provided. 1. An optical card characterized in that information including additional bits for error correction is recorded at a position closer to the center of the beam within a range to which the light beam is irradiated than a position where information including additional bits for error correction is recorded.