Method for reading out optically recorded data and device therefor

Claim 3

The method for reading out optically recorded data from an optical recording medium as claimed in Claim 1 which is characterized in that: the position of the first reference line in said sensing field is detected for temporary store and also for comparison with the stored positional data of the preceding reading to monitor whether there is any drastic change between the two, if there is no drastic change and when the reference at the predetermined order in the field is detected, the data from the track in the data recording region defined by said reference lines is read in as the proper data, and if there is a drastic change, and when a reference line at an order before or after the predetermined order in the field is detected, the data from the track in the data recording region defined by said reference lines is read in as the proper data.

Claim 6

a reading means sequentially reads out data from a starting end of a sensing field, said field covering plural data tracks including the data track to be read and reference lines defining these tracks,

Claim 7

a reading means sequentially reads out data from a starting end of a sensing field, said field covering plural data tracks including the data track to be read and reference lines defining these tracks,

Claim 8

a reference line detecting means takes out from the output signal of the reading means a signal optically corresponding to the reference lines and outputs reference line detection signals, and a reading position indicating means counts said reference line detection signals, and when reference lines at predetermined orders in the field are detected from the reference line detection signals, indicates the position of the data of the track on the data recording region defined by the reference lines. 4. The device for reading out optically recorded data as claimed in Claim 3 comprising a gate circuit which controls output of signals from said reading means, a reading position modification indicating means which detects and temporarily stores the position of the first reference line in said field, compares said position with the position from the preceding reading which is stored in advance to monitor if there is any drastic change between the two, and if there is a drastic change therebetween, directs the data reading position to be on a data recording region either before or after the order predetermined in said field and a reading position directing means which counts said reference line detection signals and if there is no such modification direction as above, when it detects the reference line on the predetermined order, outputs a gate signal to open said gate circuit while if there is such modification direction as above, when it detects the reference line either before or after the predetermined order in said field, outputs a gate signal to open the gate of said gate circuit.

Claim 9

The device for reading out optically recorded data as claimed in Claim 3 which is characterized in that: said reference line detecting means comprising a signal level discriminating means which takes out signals at a level optically corresponding to the reference line from the output signals of the reading sensor, a time duration counter which counts the duration of the signals thus taken out, and a decision means which compares whether the duration counted by the time duration counter reaches the preset reference value, and if it does, outputs reference line detection signals.

Claim 10

The device for reading out optically recorded data as claimed in Claim 4 wherein said reference line detecting means comprises, a signal level discriminating means which takes out signals at a level optically corresponding to the reference lines out of the output signals of the reading sensor, a time duration counter which counts the duration of the signals thus taken out, and a decision means which compares whether the time counted by the time duration counter reaches the preset value or not and if it does, then outputs reference line detection signals.

Claim 11

The device for reading out optically recorded data as claimed in Claim 3 wherein said reading position indicating means comprises: a reference line counter which counts the reference lines by counting the reference line detection signals to detect the reference lines defining the data recording region to be read, and a reading position decision circuit which compares the counted value from the reference line counter with the preset target value to decide the position of the data recording region to be read.

Claim 12

The device for reading out optically recorded data as claimed in Claim 5 wherein said reading position indicating means comprises: a reference line counter which counts the reference lines by counting the reference line detection signals to detect the reference lines defining the data recording region to be read, and a reading position decision circuit which compares the counted value of the reference line counter with the preset target value to decide the position of the data recording region to be read.

Claim 13

The device for reading out optically recorded data as claimed in Claim 4 wherein said reading position modification means comprises: a target reference line detector which detects the first reference line coming into the sensing field, a reading position detector which detects the position of the data in the field the reading sensor is currently reading, and a shift indicator which compares the position in the field of the first reference line detected by said target reference line detector with the position detected in the preceding reading to monitor if there is any drastic change therebetween and if so, outputs a shift indicating signal for shifting the reading position in accordance with the direction of the change.

Claim 14

The device for reading out optically recorded data as claimed in Claim 9 wherein said reading position indicating means comprises: a reference line counter which counts the reference lines by counting the reference line detection signals to detect the reference lines defining the data recording region to be read, and a reading position decision circuit which determines the position of data recording regions from which data should be read from the counted value of said reference line counter and said shift indicating signals.

Claim 15

The device for reading out optically recorded data as claimed in Claim 6 wherein said reading position modification means comprises: a target reference line detector which detects the first reference line coming into said sensing field, a reading position detector which detects the position of the data in the field the reading sensor is currently reading, and a shift indicator which compares the reading position of the first reference line in the field detected by the target reference line detector with the position detected in the preceding reading to monitor if there is any drastic change, and if so, outputs a shift indicating signal for shifting the reading position in accordance with the direction of the change.

Claim 16

The device for reading out optically recorded data as claimed in Claim 11 wherein said reading position indicating means comprises: a reference line counter which counts the reference lines by counting the reference line detection signals to detect the reference lines which define the data recording region to be read, and a reading position decision circuit which compares the counted value of said reference line counter with the preset target value to decide the position of the data recording region to be read.

Claim 19

The device for reading out optically recorded data as claimed in Claim 13 which further comprises a tracking decision means comprising: a reading position detecting means to detect the position of the output signal from the reading sensor in the field, a tolerance setting means to set a tolerance where the reference lines may be present, and a comparator which compares whether the position of the reading position is within the tolerance.