Information recording device having variable data transfer rates and verification of recording quality

• US 5,363,361 A
• Filed: 09/28/1992
• Issued: 11/08/1994
• Est. Priority Date: 03/04/1992
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Bakx, Johannes L.
• Primary Examiner(s): Psitos, Aristotelis
• Assistant Examiner(s): Wilkinson, Duncan
• Application Number:
  US07/952,027
• Time in Patent Office: 771 Days
• Field of Search: 369/54, 369/58, 369/59, 360/53, 360/51, 364/280.8, 364/281.3
• US Class Current: 369/47.33
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: G11B 2020/10731 wherein the buffer I/O can be temporarily suspended, e.g. by refusing to accept further data to be buffered
• CPC Class Codes: G11B 2020/1074 involving a specific threshold value
• CPC Class Codes: G11B 2020/10777 instructions or commands
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/005 Reproducing at a different information rate from the information rate of recording for television signals H04N5/783
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06

Abstract

An information recording device for recording digital information at a higher bit rate than that at which it is received. The difference in bit rate is compensated by an input buffer memory, read-out of a packet of information stored therein and recording thereof being periodically interrupted so as to maintain the filling level within a predetermined range. During each recording interruption, the recorded information pattern corresponding to the last recorded packet of information is read-out from the record carrier and the read-out signal is analyzed by an analysis circuit to derive an indication signal indicative of recording quality. The indication signal can be used to optimize the write parameters of the recording device, and also to determine whether re-recording of any or all of the last already recorded information packet should be performed before resuming read-out and recording of subsequent information packets from the buffer memory.

Claims

1. A device for recording information on a recording track of a record carrier at a rate greater than that at which the information is received, said device comprising:

a read and write head for producing a scanning spot at a position on the recording track determined by the position of the read and write head relative to the record carrier;

scanning means for translating the read and write head so that the scanning spot scans along the recording track;

said read and write head being adapted to be selectively set to either of a write state and a read state, in the write state being responsive to a write signal supplied thereto to record an information pattern corresponding to said write signal in the portion of the recording track then being scanned, and in the read state producing a read signal corresponding to a recorded information pattern in the portion of the recording track then being scanned;

an input buffer memory for successively receiving and temporarily storing successive packets of the information to be recorded;

buffer control means for retrieving the stored information packets from the input buffer at a rate higher than the rate at which they are received in the input buffer;

a write control circuit coupled to said read and write head and to the input buffer for receiving each packet of information retrieved from the input buffer, converting said packet into a write signal, supplying said write signal to said read and write head, and setting said read and write head to said write state so as to record said write signal as an information pattern on said recording track;

system control means coupled to said read and write head, said write control circuit, said scanning means and said buffer control means, said system control means being programmed to;

(i) cause said buffer control means to interrupt retrieval of stored information packets from the input buffer during periodic interruption intervals so as to maintain a filling level of the input buffer between predetermined limits;

(ii) during each retrieval interruption interval cause said write control circuit to set the read and write head to the read state and cause said scanning means to return the read and write head to again scan the portion of the recording track wherein the last information packet already retrieved from the input buffer has been recorded and produce a read signal corresponding to said last recorded information packet; and

(iii) upon completion of each retrieval interruption interval, cause said write control circuit to return the read and write head to the write state and cause said buffer control means to resume retrieval of packets of information from the input buffer, so that recording of succeeding packets of information is resumed; and

analysis circuit means coupled to said read and write head to receive the read signals produced thereby during said retrieval interruption intervals, and derive from said read signals a signal indicative of the quality of the recorded information patterns produced on said track during recording, whereby the retrieval interruption intervals for maintaining a predetermined filling level of the buffer memory are also utilized to derive an indication of the quality of the recorded information patterns produced during recording.

2. A recording device as claimed in claim 1, characterized in that said system control means receives said indication signal from said analysis circuit means and based thereon adjusts a write parameter applicable to said write control circuit and said read and write head which influences the relationship between information being recorded and the recorded information pattern produced therefrom.

3. A recording device as claimed in claim 1, further comprising a read circuit coupled to said read and write head for receiving the read signal produced thereby during a recording interruption, regaining from said read signal the information represented thereby, and supplying the regained information to said analysis circuit;

and wherein said analysis circuit comprises means for detecting errors in the regained information and means for counting said errors in accordance with a predetermined counting criterion, the indication signal produced by said analysis circuit being indicative of the number of counted errors.

4. A recording device as claimed in claim 3, further comprising storage means coupled to said input buffer for storing the last packet of information retrieved therefrom prior to a recording interruption;

said system control means being adapted to control said scanning means and said write control circuit so as to cause the read and write head to record at least a portion of the packet of information stored in said storage means when said indication signal signifies that the quality of the portion of the recorded information pattern corresponding to said portion of information packet fails to conform with a predetermined criterion.

5. A recording device as claimed in claim 3, further comprising means for adding an error-correcting code to the information to be recorded, and wherein said means for detecting errors is adapted to detect errors which are not correctable by means of said error-correcting code, the indication signal produced by said analysis circuit being indicative of the number of said incorrectable errors.