JP2662873B2 - Method for making write pit diameter uniform on optical information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention focuses a beam from a laser light source on an optical information recording medium by an optical pickup, detects a reflected beam thereof, and moves the pickup. Especially, in writing (recording) of information (data) in the information recording / reproducing method provided with the above servo system, the diameter of the writing spot for forming the information pit is made uniform regardless of the variation in the reflectance of the recording medium surface. For this purpose, the present invention relates to a method for controlling the emission energy from a laser light source, which is effective when optically used for writing on a recording medium, for example, a disk, a card, or the like.

2. Description of the Related Art In general, information recorded on an optical disk, for example, a laser card, is printed by forming a train of pits at a certain interval with a beam spot along a guide track on the surface of the card. It is clear that the recording density is improved by reducing the diameter and the pit interval.

On the other hand, when a continuous pit row is formed in order to use the enhanced energy for writing than in reproducing (reading) the information, the energy of the laser beam is not only consumed by burning the pit but also by heat conduction around the pit. Heat spreads radially to
Subsequently, when the pits are burned, if the energy time product consumed during the previous pit formation is used as it is, the pit diameter becomes large and must be irregular.

In addition, the detection signal of the reflected beam corresponding to the reflectance of the card is used for focus and tracking movement control of the pickup, but the reflectance of the card itself varies remarkably for each production lot, and the information bit diameter varies. When the same energy-time product is used, the variation greatly changes as well as the variation of the reflectance, and there is an indeterminate obstacle factor such that the condition given to the reading performance at the time of reproducing the recorded information is greatly changed. .

[Problems to be Solved by the Invention] As described above, the present invention can form a uniform pit despite the fluctuation of the reflectance, which is one of the attributes of the information recording medium, and as a result, a high recording density of information can be obtained. It is another object of the present invention to improve read accuracy and reduce error rate in reproducing recorded information.

"Means for Solving the Problems" In order to solve the above-mentioned technical problem, the irradiation time of the laser beam suitable for forming a uniform pit diameter according to the difference in the reflectance of the information recording medium is described. Can be achieved by varying the write pulse width.

Example An example of the present invention will be described below in detail with reference to the drawings.

First, FIG. 1 is a circuit block diagram of a system for implementing a method for equalizing the writing pit diameter of an optical information recording medium according to the present invention.

DA is an 8-bit preset data and write data, that is, a data input terminal to which information is input, and WPSD is a parallel 8-bit write preset data P ₁ , P ₂ , which enters the data input terminal.
In this embodiment, preset data is output four times at the input end of the preset serial data for generating a latch signal of P ₃ ..., And the preset latch signal 1 is used as the preset latch signal 1.
The preset data for setting the pulse width of the write pulse WP, which is sent in parallel to 41, 42, 43 and 44, respectively, is latched in these preset latch blocks.
WD is a write data latch signal for causing the parallel 8-bit write data t ₁ , t ₂ , t ₃ ... To enter the data input terminal to be latched at ₂ , and the pulses Q ₁ , Q ₂ ,
Latch with Q ₃ …. On the other hand, ψ is a clock frequency source which is a reference of timing for forming pits.
144 MHz is adopted. The frequency divider 11 divides the frequency by 1/366 to ψ ₁ = 59.57 microseconds, and the frequency divider 12 divides by _２ to ψ ₂ = 0.3255 microseconds And is used as a reference for setting the pulse width of the write pulse WP for controlling the laser light source. Reference numeral 3 denotes a parallel-to-serial converter which converts write data received in 8-bit parallel from the write data latch into serial data S in synchronism with # ₁ and outputs the serial data S, and 5 denotes a write corresponding to the serial data S A preset data selector for selecting the pulse width of the pulse WP, that is, the preset data.
When "1" is input alternately, the number of inputs of "1" is counted. In this embodiment, the count is stopped when "1" is counted four times. Is maintained, and when "0" is input for two consecutive bits, the "1" counter is cleared. Preset data is selected according to the count value of "1". Reference numeral 6 denotes a circuit for generating a write pulse WP. When the serial data S is "1", the circuit counts $ ₂ as many as the number of preset data selected by the preset data selector 5, and during the counting period, the write pulse WP is counted.
To “1”.

Next, the relationship between the time of each signal and the time of each signal in the system block diagram of FIG. 1 will be described with reference to the timing charts of the signals of the respective parts in the system block diagram of FIG.

Figure 2 is 8 bits of the pre-excisional data t _1, t _2, t ₃ ... and the write data WD _1, WD ₂ ... data DA and the parallel data t
_1, t _2, t ₃ and the input P ₁ of the pre-excisional serial data WPSD, and P _2, P ₃ ... corresponding to ..., Q _1, Q ₂ inputted from the write data latch signal input terminal WD, ... and clock source which is a graph showing the timing of severally of write pulse to be applied as a control signal to the divide by serving as a reference obtained were pit formed clock signal [psi ₁ and the laser light source.

As can be seen from the above description, the 8-bit data WD ₁ and WD ₂
, And the write data latches Q ₁ , Q _2, and the serial data S obtained by parallel / serial conversion finally becomes a trigger signal for the laser light source, and the preset data is a parameter for the irradiation time of the laser beam for writing. It has become. Can be arbitrarily changed according to the difference in the reflectance of the information recording medium.
The preset data selector 5 selects preset data t ₁ , t _2, ..., Which are preset latch outputs, while monitoring the serial data S, and counts the number of latches of the selected preset data. During this counting period, a writing pulse WP is applied to the laser light source to perform a writing operation.

[Effect] According to the method for making the writing pit diameter uniform according to the present invention, the reflected beam from the laser light source is controlled based on the energy time product required for writing, even if the reflectivity varies from part to part. Therefore, information can be written on a pit having a uniform diameter by a uniform beam spot.

Further, there is no waste in energy consumption from the laser light source added to make the pit diameter uniform, and interference between pits is prevented, and the pit diameter does not fluctuate.
In reading or reproducing recorded information, the error rate of the read data is greatly reduced, and the uniformity of the pits makes the reading accuracy remarkable and can be improved, which is of great practical benefit.

If the attribute of each information recording medium, that is, the reflectivity in the present invention is individually registered, it is suitable for extracting data from the memory of the microprocessor and adopting it as automatic processing by a computer.

[Brief description of the drawings]

FIG. 1 is a block diagram of a system for implementing the method of the present invention, and FIG. 2 is a graph showing the timing of serial data, clocks, control write pulses, and the like. WPSD …… Preset serial data P ₁ , P ₂ …
1 ...... pre excisional data la Tutsi signal unit, WD ...... write data latch signal Q _1, Q ₂ ...... input terminal, 2 ...... write data latch portion, 3 ...... parallel-serial converter, [psi ...... clock frequency source,
11, 12… divider, ψ ₁ , ψ ₂ … dividing frequency, S… serial data, DA… t ₁ , t ₂ … 8 bit data of WD ₁ ,
41, 42, 43, 44... Preset latch section, 5... Preset data selector, 6... Counter, WP.

Claims (1)

(57) [Claims] 1. An optical information recording / reproducing method for recording and reproducing information by focusing and irradiating a laser beam along a guide track on an information recording medium which cannot be optically added and erased, and detecting the reflection. At the time of writing information to the information recording medium, parallel conversion is performed from a latch output of 8-bit data and write data and a frequency-frequency-divided output as a trigger signal for causing the laser light source to emit the beam. Serial data is generated, the irradiation time is regulated by 8-bit preset data which is a parameter relating to the emission time of the laser beam, and the preset data is received in synchronism with the serial data. Latching the preset data so that the irradiation time can be varied; and receiving the serial data and the latch output. The preset data is arbitrarily selected while monitoring the serial data by a data selector, and the number of latches selected by the preset data selector is counted by a counter receiving the output of the preset data selector and the clock frequency. A method for equalizing a writing pit diameter of an optical information recording medium, wherein information is recorded by irradiating a pulsed beam onto the optical recording medium during a counting period.