JPH01185839A - Optical memory write circuit - Google Patents

Abstract

PURPOSE:To correct the dislocation of pit edge forming position caused by pre-heating effect in case of forming the immediately preceding pit and to improve error margin at the time of reproducing information by delaying the starting of optical beam projection as the interval is small based on the interval to the immediately preceding pit. CONSTITUTION:A write signal (a) is supplied to a one-shot circuit 10 through an inverter circuit 9 in a delay control circuit 2. Since the polarity of the signal (a) is inverted in the circuit 9, an interval check signal (d) of a pulse width TW is obtained at every trailing edge of the write signal (a) in the one-shot circuit 10. This interval check signal (d) is supplied to the input D of a D-type flip-flop circuit 11, and there, the polarity of the signal (d) is decided at every leading edge of it to obtain an interval decision signal (d). This signal (e) is inputted to a selector circuit 12, where a delayed write signal having the optimum delay time is selected, and thus a selected write signal (f) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical storage writing circuit that records information on a storage medium using optical means. The present invention relates to an optical storage write circuit suitable for an optical disk device that records and reproduces information.

[Conventional technology]

2. Description of the Related Art In optical storage devices such as optical disk devices, laser light is used as a means for recording and reproducing information. Information is recorded by converging this laser light into a very small spot using an optical lens and forming bits or magnetization reversal on the storage medium using the optical energy of the laser light. In addition, information is reproduced by detecting means such as changes in reflection intensity due to bits or magnetization reversal on the medium, or the Kerr effect.

A bit or magnetization reversal (hereinafter referred to as a bit) on the medium has an oval shape corresponding to stored information, as shown in waveform example 7 in FIG. Since information is reproduced by detecting the rising and falling timings of the reproduction signal (h) corresponding to the above-mentioned bit edges, it is important to form pit edges at accurate positions during recording.

Conventionally, the write circuit in this type of device receives a write signal (a) corresponding to the information to be recorded as shown in FIG. The pits 7 are formed by irradiating the medium onto the medium.

[Problem that the invention seeks to solve]

In the conventional write circuit described above, the supplied write signal and the irradiation start and end timings of the laser beam irradiated onto the medium are the same. In the case of relatively low recording densities with large pit intervals, there is no particular problem with conventional writing circuits, but
When high recording density is achieved by reducing the pit interval in order to increase the storage capacity of information, the following problems become apparent. In other words, when the pit interval becomes smaller, the medium is preheated due to the propagation of heat generated during the previous pit formation or the spread of the base of the laser beam, and this preheating effect causes the formation position of the pit front to shift toward the immediately preceding pit. appears.

Therefore, in the conventional write circuit, depending on the pattern of the information to be recorded, a shift occurs between the pit front edge when the interval with the immediately preceding pit is large and the pit front edge when the interval between the immediately preceding pit is small. This pit edge shift is a major factor in reducing the data discrimination margin during information reproduction, so conventional methods have the disadvantage of not being able to secure a sufficient reproduction error margin. The drawback was that it was not possible to achieve this.

[Means for solving problems]

The optical storage write circuit of the present invention corrects bit edge deviation, and receives a write signal that instructs the start and end of irradiation of a light beam in accordance with information on a storage medium, and performs writing. a delay means for delaying the light beam irradiation start timing in the write signal; and a recording pause interval that is the interval on the medium between the corresponding light beam irradiation start timing in the write signal and the light beam irradiation end timing in the immediately preceding write signal. and a delay control means for controlling the delay time of the delay means accordingly, and is characterized in that the shorter the recording pause interval, the longer the delay time is used for recording.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention includes a delay line 1 having a plurality of output taps, a delay control circuit 2, a write current drive circuit 3, a write optical head 4, a laser diode 5, and an optical storage medium. 6 and a motor 8. Note that the delay control circuit 2
is composed of an inverter circuit 9, a one-shot circuit 10, a D-type flip-flop circuit 11, a selector circuit 12, and an AND circuit 13. Moreover, FIG. 2 is an operation waveform diagram according to the embodiment of FIG. 1, and each waveform (a) to (g) shows an example of the operation waveform of each part (a) to (g) in FIG. There is.

Write signal (a) corresponding to recorded information on optical storage medium 6
are the delay line 1 and the inverter circuit 9, D in the delay control circuit 2.
It is supplied to a type flip-flop circuit 11. First, the delay line 1 has a plurality of output taps, and from a write signal (a) which is an input signal, a delayed write signal is created by giving various delay times to the same signal as necessary. . However, in the waveform diagram of FIG. 2, the delay time T is the minimum. . delayed write signal (b) and delay time T. Only the l delayed write signal (c) is shown as a representative. These delayed write signals are supplied as selected inputs of the selector circuit 12 in the delay control circuit 2.

On the other hand, the write signal (a) is supplied to the one-shot circuit 10 via the inverter circuit 9 in the delay control circuit 2. In the inverter circuit 9, the polarity of the write signal (a) is inverted, so in the one-shot circuit IO, the write signal (a)
An interval check signal (d
) is obtained. Note that the pulse width Tw of the interval check signal (d) is T, <T, <2T with respect to the minimum write signal interval T0.
, is set at the time of. This interval check signal (d
) is supplied to the D input of the D-type flip-flop circuit 11, where the polarity of the write signal (a) is determined every time the write signal (a) rises, and an interval determination signal (e) is obtained. That is, by the operations of the one-shot circuit 10 and the D-type flip-flop circuit 11, it is determined whether the 0 level interval of the write signal immediately before the rise of the write signal (a) was To.

This interval determination signal (e) is supplied as the first selection condition to the selector circuit 12, and the write track position information on which information is to be recorded is input to the selector circuit 12 as the second selection condition. The delayed write signal having the optimum delay time is selected from both selection conditions, and the selected write signal (f) is obtained.

In the waveform diagram of FIG. 2, if the O level interval immediately before the rise of the write signal (a) is To, the delayed write signal (c) with a delay time of Tn+ is selected; otherwise, the delay time T. . This shows that the delayed write signal (b) is selected as the selected write signal ('').Next, in the AND circuit 13, the selected write signal ('') and the delayed write signal (b) are selected as the selected write signal (''). A match is made and a write drive signal (g) is obtained.

With the above circuit operation, the write drive signal (g) has a signal waveform whose rise is delayed by (Tn+TDO) when the 0 level interval of the write signal immediately before the rise of the write signal (a) is To. In other cases, the write signal (a
) has the same signal waveform.

The write current drive circuit 3 converts the write drive signal (g) into a current, which is supplied as a laser drive current to the laser diode 5 in the write optical head 4. Since the laser diode 5 obtains an optical output proportional to the supplied drive current, the waveform of the laser light is the same as the write drive signal (g). Thereafter, the laser beam is focused by an optical lens in the writing optical head 4, and is focused on a storage medium 6 which is rotated at a constant rate by a motor 8.
Because of the upward irradiation, pits 7 as shown in FIG. 3 are formed on the medium.

According to the above embodiment, since the storage medium 6 rotates at a constant rotational speed, the moving speed of the medium is detected from the write track position information corresponding to the diameter of the medium, and also corresponds to the irradiation pause time of the light beam. The recording pause interval on the medium is detected by checking the time from the fall to the rise of the write signal (a).

Therefore, the correspondence between the amount of deviation in the formation position of the bit edge and the bit interval, which occurs due to the shortening of the distance from the immediately preceding pit, is determined in advance through experiments, and the delay of the delayed write signal is set for each track in order to cancel out the amount of deviation. If the position is determined in advance, the circuit operation of this embodiment makes it possible to form a pit edge at an accurate position on the medium.

In addition, in the above embodiment, the correction on the recording information button is performed only when the bit interval corresponding to the pause in the light beam irradiation becomes the minimum To, but this is not particularly limited. Depending on the conditions, it is also possible to perform a plurality of corrections corresponding to each bit interval occurring on the information button.

〔Effect of the invention〕

As explained above, the present invention is capable of delaying the start timing of light beam irradiation as the interval becomes smaller, depending on the interval from the previous bit, when forming pits on the medium in response to the supplied write signal. As a result, the deviation of the bit edge formation position caused by the preheating effect during the immediately preceding pit formation is corrected, so there is an effect of improving the error margin during information reproduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an operation waveform diagram of the embodiment shown in FIG. 1, and FIG. It is a diagram showing correspondence. ■...Delay line, 2...Delay control circuit,
3... Write current drive circuit, 4... Write optical head, 5... Old laser diode, 6...
・Optical storage medium, 7... pit, 8...
Motor, 9... Inverter circuit, 10...
・・One shot circuit, 11・・D type flip-flop circuit, 12・・Selector circuit, 13・
...And circuit. Agent Patent Attorney Uchihara Otohama 2 (Ko \ku-\-

Claims (1)

[Claims] In an optical storage writing circuit that records binary digital information on a storage medium using a focused light beam, writing that corresponds to information on the storage medium and instructs the start and end of irradiation of the light beam delay means for receiving a signal and delaying the light beam irradiation start timing in the write signal;
a delay for controlling a delay time in the delay means according to a recording pause interval that is an interval in the storage medium between the light beam irradiation timing in the write signal and the light beam irradiation end timing in the immediately preceding write signal; 1. An optical storage write circuit comprising: a control means, the shorter the recording pause interval, the longer the delay time to record information.