Optical writing and reading method and optical writing and reading apparatus

Claim 2

An optical writing and reading method for writing a mark and data on each recording section of a recording medium, said recording section having a mark recording region and a data recording region, said mark indicating that said data is already written on said data recording region, said method comprising the steps of: irradiating light on said mark recording region to write a mark, discriminating, during said irradiating step to write a mark, whether or not a mark is already written on said mark recording region, by comparing the light quantity reflected from said mark recording region with a reference value, and inhibiting the subsequent writing of data when a discrimination is made in said discriminating step that a mark is already written on said mark recording region.

Claim 3

An optical writing and reading method as claimed in claim l, wherein said mark is written by continuously irradiating light on said mark recording region for a period longer than any period of irradiation for writing data.

Claim 4

An optical writing an reading method as claimed in claim l, wherein said recording medium has a characteristic of a lower reflection coefficient at a portion where recording light is already irradiated, and during said irradiating step of write a mark, when the light quantity reflected from said mark recording region is discriminated as lower than said reference value, a discrimination is made that a mark is already written on said mark recording region.

Claim 5

An optical writing and reading method as claimed in claim l, wherein said recording medium has a characteristic of a higher reflection coefficient at a portion where recording light is already irradiated, and during said irradiating step for writing a mark, when the light quantity reflected from said mark recording region is discriminated as higher than said reference value, a discrimination is made that a mark is already written on said mark recording region.

Claim 6

An optical writing and reading method as claimed in claim l, wherein said reference value is obtained from a digital/analog converter having an input for receiving a voltage control signal, said voltage control signal being a digital data representing the light quantity irradiated on said recording medium.

Claim 7

An optical writing and reading method as claimed in claim l, wherein said reference value is obtained directly from a laser diode for emitting light to be irradiated on said recording medium.

Claim 8

An optical writing and reading method as claimed in claim 6, wherein said reference value is obtained directly from the light to be irradiated on said recording medium.

Claim 9

An optical writing and reading method as claimed in claim 6, wherein said reference value is obtained from a monitoring light emitted from said laser diode.

Claim 10

An optical writing and reading method as claimed in claim l, wherein said method employs a one beam system utilizing one light beam for both writing and reading operations, said light beam having a larger power during writing, and said light beam having a smaller power during reading.

Claim 11

l0. An optical writing and reading method as claimed in claim l, wherein said method employs a two beam system utilizing two light beams having different frequencies, one of said light beams being used for writing and the other of said light beams being used for verifying and reading the written data, said two light beams being respectively irradiated on said data recording region and on said mark recording region simultaneously.

Claim 12

An optical writing and reading method as claimed in claim l0, wherein the reflected write beam and the reflected read beam are separated by a dichroic mirror.

Claim 13

An optical writing and reading method as claimed in claim l, wherein said method employs a two beam system utilizing two light beams having the same frequency, one of said light beams being used for writing and the other of said light beams being used for verifying and reading the written data, said two light beams being respectively irradiated on said data recording region and on said mark recording region simultaneously.

Claim 14

An optical writing and reading method as claimed in claim l2, wherein the reflected write beam and the reflected read beam are seperated by a spatial filter.

Claim 15

An optical writing and reading apparatus comprising: a recording medium (l) having a plurality of recording sections, each of said recording sections having a mark recording region and a data recording region, said mark indicating that said data is already written on said data recording region, a light irradiating means (7,2) operative­ly receiving said mark and said data to irradiate light on said recording medium for writing said mark and said data; a light detecting means (23) for detecting a light quantity reflected from said recording medium during writing of said mark; a light-voltage converting means (235) for converting said reflected light quantity into a detected voltage ((a)); a reference voltage generating means (3} for generating a reference voltage ((b)) corresponding to a predetermined reflected light quantity; a comparing means (4), operatively connected to receive said detected voltage ((a)) and said reference voltage ((b)), for comparing said detected voltage ((a)) with said reference voltage ((b)) to provide an output signal (c) indicating whether or not a mark is already written in said mark recording region; and a gate means (6), operatively connected to receive the output signal (c) of said comparing means and said data, for inhibiting, depending on said output signal (c), supply of said data to said light irradiating means.

Claim 16

An optical writing and reading apparatus comprising: a recording medium (l) having a plurality of recording sections, each of said recording sections having a mark recording region and a data recording region, said mark indicating that said data is already written on said data recording region, a light irradiating means (7,2) operative­ly receiving said mark and said data to irradiate light on said recording medium for writing said mark and said data; a light detecting means (23) for detecting a light quantity reflected from said recording medium during writing of said mark; a light-voltage converting means (235) for converting said reflected light quantity into a detected voltage ((a)); a reference voltage generating means (3} for generating a reference voltage ((b)) corresponding to a predetermined reflected light quantity; a comparing means (4), operatively connected to receive said detected voltage ((a)) and said reference voltage ((b)), for comparing said detected voltage ((a)) with said reference voltage ((b)) to provide an output signal (c) indicating whether or not a mark is already written in said mark recording region; and a gate means (6), operatively connected to receive the output signal (c) of said comparing means and said data, for inhibiting, depending on said output signal (c), supply of said data to said light irradiating means.

Claim 17

An optical writing and reading apparatus as claimed in claim l4, wherein said mark is written by continuously irradiating light on said mark recording region for a period longer than any period of irradiation for writing data.

Claim 18

An optical writing and reading apparatus as claimed in claim l4, wherein said reference voltage generating means (3) comprises a digital/analog con­verter (3a) for converting a reference digital voltage control signal into an analog voltage, said reference digital voltage control signal corresponding to the light quantity emitted from said light irradiating means.

Claim 19

An optical writing and reading apparatus as claimed in claim l4, wherein said reference voltage generating means (3) comprises: a beam split prism (3l) for monitoring the light quantity emitted from a laser diode in said light irradiating means to said recording medium; a photo detector (32) for converting the light quantity monitored by said beam split prism into an electric signal; and an amplifier (33) for converting said electric signal output from said photo detector into said reference voltage ((b)).

Claim 20

An optical writing and reading apparatus as claimed in claim l4, wherein said reference voltage generating means (3) comprises: a photo detector (34), arranged to receive a monitoring light quantity emitted from a laser diode in said light irradiating means, said monitoring light quantity being emitted in a direction different from the direction of the light quantity emitted from said laser diode to said recording medium, said photo detector operatively converting said monitoring light quantity into an electric signal; and an amplifier (35) for converting said electric signal output from said photo detector into said reference voltage ((b)).

Claim 21

An optical writing and reading apparatus as claimed in claim l4, wherein said apparatus employs a one beam system utilizing one light beam for both writing and reading operations, said light beam having a larger power during writing, and said light beam having a smaller power during reading.

Claim 22

An optical writing and reading apparatus as claimed in claim l4, wherein said apparatus employs a two beam system utilizing two light beams having different frequencies, one of said light beams being used for writing and the other of said light beams being used for verifying and reading the written data, said two light beams being respectively irradiated on said data recording region and on said mark recording region simultaneously.

Claim 23

2l. An optical writing and reading apparatus as claimed in claim 20 further comprising a dichroic mirror for separating the reflected read beam and the reflected write beam.

Claim 24

An optical writing and reading apparatus as claimed in claim l4, wherein said apparatus employs a two-beam system utilizing two light beams having the same frequency, one of said light beams being used for verifying and reading the written data, said two light beams being respectively irradiated on said data recording region and on said mark recording regin simultaneously.

Claim 25

An optical writing and recording apparatus as claimed in claim 22 further comprising a spatial filter for separating the reflected read beam and the reflected write beam.