JPS5841444A - Information writing system of optical disc - Google Patents

Abstract

PURPOSE:To reduce registering time of data and to prevent destruction of files, by recording written flags and the data altogether. CONSTITUTION:In addition to normal writing units such as a clock synchronizing signal 17, a data synchronizing signal 18, and user's data 19, data 16 representing the end of writing is provided prior to them to constitute the minimum unit of the writing data. The data representing the end of writing is written at the same time when the user's data is written and a write protection function can be provided by detecting duplicated writing of the data after being written.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an optimal write protection method for an optical disk device that can simultaneously monitor data on a medium while writing data on the medium.

The write protect function for conventional optical disk devices is similar to that for magnetic disks, reading the ``written'' FLAG and protecting double W&. If you do this, writing user data and
'Since it is not possible to write to the colored FLAG at the same time, in devices such as optical disk devices that rotate more than lθ times slower than magnetic disk devices, the time it takes to register user data becomes significantly longer, resulting in a decrease in processing performance. Connect.

The purpose of the present invention is to shorten the registration time of user data by writing the ``written'' FLAG and user data together, and to prevent file destruction due to runaway of one program or hardware abnormality.

In current optical disk devices, while data is being written on the medium through the recording head, information at the same location can be simultaneously monitored using the reading head.

Therefore, when a waveform different from the 7 write waveforms is read, it can be detected that information has already been written on the medium. Because of this, double writing can be detected simultaneously during a write operation, and if this is detected before reaching the user data area, the user data area can be detected. It will not be destroyed.

An embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 describes the configuration of the optical head and the manual input of the waveform difference detection circuit. The operation will be explained below. The omitted data 1 and the write clock 2 are input to the write amplifier 4, and the output thereof is sent to the optical head 15.
into the laser diode 5. The output of the laser diode 5, that is, the laser beam, is transmitted through a lens 6, a prism 7, a reflecting mirror 8, a lens 9. A hole (information) is made in the medium 12 by passing through the hole. At this time, the laser beam hitting the medium is reflected, passes through a folding lens 9, a reflection shifter 8, and a prism 7, and enters a photodetector 10. As a result, it is possible to see the state of the medium of color at the same time as the vow. The output of the photodetector 10 is passed through a read amplifier 11 and becomes an input to a waveform difference detection circuit 120. The output of the write amplifier 4 is also input to this waveform difference detection circuit 12 . By looking at these inputs, the waveform difference detection circuit 12 determines whether the waveform is written in a previously written area or whether the waveform indicates normal writing. The result determined in this way is valid only at detection timing 14,
Issues signal 3 to interrupt writing.

FIG. 2 shows the user data area in track format. Usually, the clock synchronization signal 17, data synchronization signal 18, and user data 19 are the minimum write unit. In the method of the present invention, prior to these, “written”
Add data 16 (allowing multiple writing) indicating . Therefore, 16 to 19 are taken as the minimum unit of v/i@ included data. Then, when double writing is detected in one area where one area has been written, the next writing after 17 is interrupted.

By doing this, data indicating "written" can be written at the same time as user data is written, and by detecting double writing of "1 written" data,
Achieves write protection function.

3 and 4 are diagrams showing details of the waveform difference detection circuit 12.

FIG. 3 is a time chart showing the relationship between the output 20 of the write amplifier 4 and the output 21, 21' of the read amplifier 11. The signal 21U is the output waveform during normal operation, and the signal 21' is the waveform during double writing. Further, the bit 22 shown by a solid line indicates a bit that has already been written, and the next bit 23 shown by a dotted line indicates a bit newly written by the write signal 2°. Dotted line 24
．． 25f'i indicates the rounding boundary level for detecting differences.

As can be seen from this figure, the direction in which the difference appears in the double-written portion differs depending on the positional relationship with the bit signal 20. That is, there are two types: positive direction and negative direction with respect to the DC level.

FIG. 4 shows a circuit for detecting the difference waveform in the double writing portion shown in the time chart and for detecting double writing. This circuit consists of comparators 31, 32, AND circuit 33, O
It is composed of R, a circuit 34, and a collar 7fi30. The comparator 31 receives the boundary level 25 and the output 21' of the read amplifier 11 in order to detect the above-mentioned difference waveform in the negative direction, and detects the write clock 20 and the misaligned bit. In order to detect a difference waveform in the positive direction, the boundary level 24 and the output 21' of the read amplifier 11 are input to the zero comparator 31, and the result is inverted. Then, this and the output 20 of the write amplifier 4 are connected to A
The input to the ND circuit 32 creates a signal 28 indicating that the bit has already been written. signal 26.28
becomes the input clock of the counter 30 via the OR circuit 34. The counter 30 is cleared by a reset signal 29 issued when starting writing to the 'written' area, and a signal 14 indicating the period of one 'written' area.
It is counted only during As a result, a signal 3 for detecting double writing and interrupting the write operation is generated when the counter 30 exceeds a predetermined number.

According to the present invention, since the ``written'' data and the original user data can be written simultaneously, the recording of user data can be completed in one rotation of the disk, and the write protect function can be easily implemented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the relationship between the optical head and the waveform difference detection circuit, FIG. 2 is a diagram showing the format of the user data area on the track, and FIGS. It is a figure showing an example. Agent Patent Attorney Toshiyuki Usuda ε Sho￥h 1 Figure 2 Figure 2

Claims (1)

[Claims] In an information writing method for an optical disc that has a read head that can monitor the same position at the same time while the write head is in operation, it is necessary to read whether or not data has already been written. An information writing method for optical discs that detects the output of the disk head and adds "written" data immediately before the user data to be written as a t% mark.