Binarization device

• US 20030048726A1
• Filed: 09/12/2002
• Published: 03/13/2003
• Est. Priority Date: 09/13/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Sasa, Noboru
• Granted Patent: US 7,085,429 B2
• Time in Patent Office: Days
• US Class Current: 369/59.17
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence

Abstract

The present invention provides a binarization device that realizes reproduction with a low error rate, even where optimum recording conditions such as recording power have not been set in the recording device, or where optimum recording has not been carried out for the reproducing device. The binarization device includes a binarization unit, a slice level setting unit, and a weight adding function. The binarization unit binarizes a reproduction signal obtained by reproducing information recorded by mark length recording on a recording medium to output high-level signals and low-level signals based on a slice level. The slice level setting unit calculates the average value of the high-level signals output from the binarization unit, and determines the slice level from the average value. The determined slice level is set to the binarization unit. Either the binarization unit or the slice level setting unit adds a predetermined weight to each signal having a short high-level time among the high-level signals.

Claims

1. A binarization device comprising:

a binarization unit that binarizes a reproduction signal obtained by reproducing information recorded by mark length recording on a recording medium to obtain high-level signals and low-level signals based on a slice level;

a slice level setting unit that calculates the average value of the high-level signals output from the binarization unit, further calculates the slice level based on the average value, and sets the slice level to the binarization unit; and

a weight adding means of adding a predetermined weight to each signal having a short high-level time among the high-level signals.

4. The binarization device as claimed in claim 1, wherein the weight adding means serves to decrease the level value of each of the high-level signals with a lapse of output time.

5. The binarization device as claimed in claim 1, wherein the weight adding means serves to give a level value to each signal having a short high-level time in such a manner that the shorter high-level time a signal has, the greater level value the signal is given.

6. The binarization device as claimed in claim 1, wherein a fluctuation of the slice level is made greater than a fluctuation of the center value of amplitude of the second shortest mark length in the reproduction signal.

7. The binarization device as claimed in claim 1, wherein the weight adding means adds a predetermined weight to each signal having a short high-level time, so that curves representing recording mark length dependencies of the differences among mark lengths and space lengths recorded on the recording medium cross between the shortest mark length and the second shortest mark length.

8. The binarization device as claimed in claim 1, further comprising:

an amplitude center value detecting unit that detects the amplitude center value of the shortest mark length in the reproduction signal; and

a slice offset adding unit that adds a slice offset value to the slice level determined by the slice level setting unit, so that the slice level to be set to the binarization unit matches with the amplitude center value detected by the amplitude center value detecting unit.

9. The binarization device as claimed in claim 1, wherein the recording medium has physical change parts that are formed in two non-recording areas between which a track having marks recorded thereon is located, with the center line of the track being the center line of the asymmetrical situation of the physical change parts.

2. A binarization device comprising:

a binarization unit that binarizes a reproduction signal obtained by reproducing information recorded by mark length recording on a recording medium to output high-level signals that are above a slice level and low-level signals that are below the slice level, and further binarizes the reproduction signal to output low-level signals that are above the slice level and high-level signals that are below the slice level;

a slice level setting unit that calculates the average value of the former high-level signals and the average value of the latter high-level signals, further calculates the average value of the former high-level signal average value and the latter high-level signal average value, determines the slice level from the last average value, and sets the slice level to the binarization unit; and

a weight adding means of adding a predetermined weight to each signal having a short high-level time among all the high-level signals.

3. A binarization device comprising:

a binarization unit that binarizes a reproduction signal obtained by reproducing information recorded by mark length recording on a recording medium to output high-level signals that are above a slice level and low-level signals that are below the slice level, and further binarizes the reproduction signal to output low-level signals that are above the slice level and high-level signals that are below the slice level;

a slice level setting unit that calculates the average value of the former high-level signals and the average value of the latter high-level signals output from the binarization unit, selects one of the two average values based on the condition of the reproduction signal, calculates the slice level from the selected average value, and sets the slice level to the binarization unit; and

a weight adding means of adding a predetermined weight to each signal having a short high-level time among all the high-level signals.