Information record medium having a header having error correction code added for each block and a method for recording information on such a medium

0001The present invention relates to an information record medium having information thereof divided into a plurality of blocks and a method for recording information on such a medium.

Background Art

0002Floppy disk magnetic tape and compact disk have been used as information record media. In those media, information is written data block by data block such as sector or record. The block includes a data field as well as block information concerning the block per se. In the floppy disk, it may be track number, sector number and CRC (Cyclic redundancy check). For example, U. S. Patent Number 4888753 specification, lines 12-25 and Fig. 1 describes and shows that information is recorded block by block on a card-like optical record medium (optical card) and an address is added to each block. JP-A-5891512 shows a medium in which a CRC error detection code is provided for the block information header field, but the data is not encoded. On the other hand, in an information record medium having a high data error rate, data is converted to information having an error correction code (ECC) added thereto to correct an error for each block. The ECC has a very high error correction capability but it uses a substantial portion of the block.

0003The IBM floppy disc standard, described in WIRELESS WORLD, Volume 88, No 1561, October 1982 pages 80 - 82, 84, Sheepen Place, Olchester; J.R. Watkinson. "Floppy-Disc Drives", employs an error detecting CRC byte following the header field and a separate two-byte error detecting CRC code following the data field. The NASA DSTP data management system described in DIGEST OF PAPERS - 7TH IEEE SYMP ON MASS STORAGE SYSTEMS, Arizona, US, 4-7 November 1985, pages 38 - 42, IEEE, D Thomas: "A high speed data management system with on-line optical disk storage" discloses a medium on which packets comprising a header and error correction encoded data are stored, the coding co-efficients likewise being stored.

0004Accordingly, for information which does not require high quality of data such as image information or music information, the ECC is not used but the corresponding area is used for raw data.

SUMMARY OF THE INVENTION

0005It is an object of the present invention to provide an information record medium which allows reproduction of reliable information while maintaining sufficient capacity to record data, and a method for recording information on such a medium.

0006Accordingly, the invention provides, in one aspect, an information record medium upon which information is recorded in a plurality of blocks, each said block comprising a data field within which information to be reproduced is recorded, and a header field including information identifying that block, the block further comprising header field error encoding data, characterized in that the block further comprises an indicator field indicating whether or not the data field is encoded employing an error correction code. A method of recording, and of reading, such a medium are likewise provided, as are an apparatus for recording and/or reading such a medium.

0007Other aspects and preferred features are as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

0008<ul id="ul0001" list-style="none"><li>Fig. 1 shows an information recording and reproducing apparatus which uses an information record medium of the present invention,</li><li>Fig. 2 shows a plan view of one embodiment of the information record medium of the present invention,</li><li>Fig. 3 shows a flow chart of a procedure for recording information on the medium of the present invention,</li><li>Figs. 4 and 5 show flow charts of a procedure for reproducing the information from the medium of the present invention, and</li><li>Fig. 6 shows a plan view of another embodiment of the information recording medium of the present invention.</li></ul>

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0009In the following description of the embodiments of the information record medium, an optical card is explained.

0010Fig. 1 shows an information recording and reproducing apparatus used in the present invention.

0011The information recording and reproducing apparatus (drive unit) is connected to a host control unit (host) 6 and data is communicated and controlled between the drive 5 and the host 6. A microprocessing unit (MPU) 7 in the drive unit 5 contains a read-only memory (ROM) and a randam access memory (RAM), and it primarily controls a card feed motor 11 and a head drive motor 10. An auto -tracking (AT)/auto-focusing (AF) control circuit 8 receives a signal from a photosensor 13 to drive an AF actuator 14 and an AT actuator 15. A modem circuit 9 records data by changing an intensity of a light source 12 in a record mode, and demodulates data by a signal from the photo-sensor 13 in a reproduce mode.

0012The host 6 sends and receives data to and from the drive unit 5 to record and reproduce information for each block of an optical card 1 which is the information recording medium.

0013Since the optical card 1 has a high error rate because of the nature of the medium, error correction means is necessary when highly reliable information is required.

0014Fig. 2 shows a plan view of the optical card of the present invention.

0015Tracks 2₁, 2₂, 2₃, ..... 2_n which are information record blocks are formed in parallel on the optical card 1. Each of the tracks comprises a header field 4 which contains block information and a data field 3. The header field 4 includes a track number of the corresponding track which is address information of the block and information indicating presence or absence of ECC in the data field 3. The data field 3 has either the ECC added thereto to possess an error correction ability or no ECC added thereto. The optical card 1 is reciprocally moved in the directions of F and R in Fig. 2 to record and reproduce the information. The header field 4 is treated as a unit and the ECC is added thereto so that it possesses the error correction ability. Since the header field requires high reliability, it has always the ECC added thereto, unlike the data field.

0016Fig. 3 shows a flow chart of a procedure to write data onto one track of the optical card. Prior to the writing, data to be recorded is divided into a plurality of blocks by a predetermined information unit. A header field is added to each of the divided data to form one track of information.

0017In a step S1, the data to be recorded in the header field is converted to data with the ECC. In a step S2, whether the ECC is to be added to the data field or not is checked, and if it is not to be added, the process proceeds to a step S4. If it is to be added the process proceeds to a step S3 where the data is converted to data with ECC. In the step S4, one track of data comprising the header field and the data field is recorded on the optical card.

0018Fig. 4 shows a flow chart of a procedure to reproduce the data recorded on the optical card.

0019In a step T1, one track of data recorded on the optical card is read. In a step T2, the header field with the ECC in the track is converted to the original data. In a step T3, whether the data field is with the ECC or not is checked based on the converted header data. If it is without the ECC, the process terminates. If it is with the ECC, the data with the ECC in the data field is converted to the original data. If only the content of the header field is to be detected such as in a track search mode, only the header field may be read instead of the entire one track in the step T1 of Fig. 4.

0020Fig. 5 shows a flow chart of a further detail of the process of data reproduction.

0021In a step U1, one track of data recorded on the optical card is read, and the header field with the ECC is converted to the original data. In a step U2, whether the data reproduction has been completed or not is checked, and if it has been completed, the process proceeds to a step U3 where whether the data field is with the ECC or not is checked based on the data converted header data. If it is without the ECC, the process proceeds to a step U6 where the process waits until entire data field is read. If it is with the ECC, the process proceeds to a step U4 where the data with the ECC is converted to the original data. In a step U5, the process terminate when the entire data is reproduced.

0022Fig. 6 shows a plan view of another embodiment of the optical card of the present invention. In Fig. 6, the like elements to those shown in Fig. 2 are designated by the like numerals and detailed explanation thereof is omitted.

0023In this embodiment, header fields 4A and 4B are provided at the opposite ends of each of the tracks 2₁, 2₂, ..... 2_n. Each of the header fields 4A and 4B contains the same information, that is, a track number and information indicating the presence or absence of the ECC in the data field. Each of the header fields 4A and 4B has separately ECC added thereto. The optical card is reciprocally moved in the directions of F and R to record and reproduce information. In the present embodiment, the header field can be read first in both the forward movement and the backward movement. Accordingly, whether the data field is with the ECC or not is immediately determined and real time information processing is attained.

0024The present invention is applicable to not only the optical card but also any other medium such as disk or tape.