JPS63255881A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To decrease a data error by providing an off-setting deciding circuit to decide whether a data error detected by a data error detecting circuit is increased or decreased and output the signal of a constant code and a constant level with the deciding result. CONSTITUTION:When an off-setting deciding circuit connected to an error detecting circuit 2 decides that the data errors are increased, the positive or negative off-setting by a step of a constant quantity is set to an off-setting memory 20 and the off-setting in accordance with the contents of the off-setting memory 20 is added to a servo system. For the result to add the off-setting, it is decided whether or not the off-setting should be added, by observing the number of data errors again by the off-setting deciding circuit 19. By turning such a long, the loop system with the smallest number of data errors can be constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording and reproducing apparatus for recording and reproducing information signals using an optical disk.

BACKGROUND OF THE INVENTION In recent years, optical disk devices have come to occupy an important position as the next generation's main recording media, and the progress in their research, development, and commercialization has been very remarkable.

This optical disk device records information.

When reproducing or erasing, it is necessary to make the minute light spot created by the laser beam accurately follow the information pits, information marks, or guide grooves on the optical disk recording medium, and for this purpose, the objective lens actuator is used. The focus and tracking servo circuits used are always used.

A conventional servo circuit of this kind is, for example, shown in a reference document (``Key Points of Optical Pickup System Design'', supervised by Kazuo Noda, Japan Industrial Technology Center, January 1, 1988).

Hereinafter, the conventional optical recording/reproducing apparatus as described above will be explained with reference to the drawings.

FIG. 2 shows an optical recording/reproducing circuit including a control loop for one of the two-dimensional servo systems consisting of a focus servo circuit and a tracking servo circuit.

The configuration and operation of an optical disk device that supports a conventional servo system will be explained.

Digital input data 1 to be recorded sent from an external device such as a computer is processed by an error detection and correction circuit (hereinafter referred to as EC).
C) and a signal processing circuit 2 add an error code to the signal, perform signal processing such as interleaving, and send it to a modulation circuit 3. The modulation circuit 3 applies digital modulation appropriate to the characteristics of the optical disk medium, and then sends the signal to the laser drive circuit 4, which causes the laser 6 of the optical head 5 to emit light. The light from the laser 6 is focused by the optical system 7 and passes through the objective lens of the objective lens actuator 8 to become the disc incident light 9.
As a result, a light spot is accurately connected on the track of the disk 1o, and recording is performed.

The reflected light 11 from the disk 1o is returned to the objective lens actuator 8 and sent to the signal detection circuit 12 through the detector of the optical system 7. The signal detection circuit 12 passes the output of the detector through the signal processing circuit 12 to obtain a servo error signal 13 and an RF signal 15. Servo error signal 1
3 is a signal representing the amount of deviation of the optical spot from the mark on the track of the disk 1o;
There are a focus error signal and a tracking error signal.

In FIG. 2, these two are shown together.

The servo error signal 13 is subjected to phase compensation by a compensation circuit 14, and is passed through an amplifier (not shown) to a drive signal 16 to drive the objective lens actuator 8. At this time, the servo loop operates so that the servo error signal becomes 0, so that the light spot can accurately follow the information mark on the track. The nine RF signals 15 detected by the signal detection circuit 12 during reproduction are sent to the data detection circuit 16.
The data is converted into digital data and becomes detected data 17.

The detected data 17 passes through a demodulation circuit 18, which is exactly opposite to the modulation circuit 3 during recording, and is deinterleaved by the ECC and signal processing circuit 2 to detect error data.

After correction, output data 1 becomes the same as input data 1.

In this way, the circuit shown in FIG. 2 can also control the light spot to follow the information marks on the track and record and reproduce the information marks.

Problems to be Solved by the Invention However, in the conventional optical recording/reproducing device, the control loop was only configured and optimized so that the servo error signal became 0. Temperature changes due to

There was a problem in that it was not possible to follow the total heat change over time.

If there is a temperature drift in the optical components or optical detector that generates the servo error signal, or a physical position shift due to changes over time, setting the servo error signal to 0 will cause a focus shift or tracking shift. It is also supposed to cause

The present invention is intended to solve these conventional problems, and aims to provide an excellent optical recording and reproducing device that is free from focus deviation and tracking deviation, and therefore has fewer data errors.

Means for Solving the Problems In order to achieve the above object, the present invention determines whether the data errors detected by the data error detection circuit are increasing or decreasing; An offset determination circuit that outputs a signal with a constant sign and a constant level; an offset memory circuit that stores the output of the offset determination circuit; and by reading the contents of the offset memory circuit, the servo error signal has a constant sign and a constant amount. The configuration includes an offset adding circuit that adds an offset of .

Operation The present invention has the above-described configuration, and when the offset determination circuit connected to the error detection circuit determines that the number of data errors has increased, the offset is set in positive or negative increments of a certain amount. It is set in memory and added to the offset force servo system according to the contents of the offset memory. As a result of adding the offset, it is determined whether or not an offset should be added (by observing the number of data errors again in the offset judgment circuit). By running such a loop, a loop system with the least number of data errors can be constructed.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the same blocks as in FIG.

Signals are indicated by the same numbers and explanations are omitted.

In FIG. 1, an offset determination circuit 19 receives information on the number of data errors detected by the FCC and signal processing circuit 2, and determines whether the data errors are increasing or decreasing based on a certain threshold value. do. If there is a decreasing trend, a fixed amount of offset with the same sign as the offset set one cycle ago is added to the offset set one cycle ago and written in the offset memory 20. If the number of data errors in the correspondence is increasing, add a certain amount of offset with the opposite sign to the offset set one cycle ago to the offset set one cycle ago, and write an offset memo I.
Write to J-20. Therefore, in this case, a certain amount of offset is subtracted from the offset amount one cycle before.

The offset of the contents of the offset memory 2o is read out by the offset adding circuit 21 and is processed as follows. A certain amount of offset is added to the servo error signal 22 of the servo system. As a result, the servo system is driven to produce a certain amount of servo error signal 22, and the temperature drift of the optical system, track deviation due to constant pressure change over time, and focus deviation are canceled. The control system is then configured to reduce data errors.

Also, offset memo! The J-20 may be provided with two memories: a long-time memory that corresponds to changes over time, and a relatively short-time memory that corresponds to temperature changes, and the offset adding circuit 21 may read out the sum of both. In this case, the long-term memory may be a memory that does not volatilize depending on whether the power of the device is turned on or off. In the offset determination circuit 19, the memory is rewritten for a long period of time in the initial comparison cycle when the power is turned on, and the memory is rewritten for a short time as the temperature of the device increases. In this way, detection data 17 with relatively few data errors can be obtained even when the power is turned on.

Effects of the Invention As described above, according to the present invention, a servo system with less track deviation and focus deviation due to temperature changes and changes over time can be constructed, and an optical recording/reproducing device with extremely few data errors can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram relating to signal processing of an optical recording/reproducing apparatus showing one embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1... Input/output data, 2... ECC and signal processing circuit, 3... Modulation circuit, 4...
...Laser drive circuit, 5...Optical head, 6.
...Laser, 7...Optical system. 8... Objective lens actuator, 9...
...Incoming light. 10...disc, 11...reflected light,
12... Signal calibration circuit, 13... Servo error signal, 14... Compensation circuit, 16...
... Drive signal, 16 ... Data detection circuit, 1 completion ... Detection data, 18 ... Demodulation circuit,
19...Offset judgment circuit, 20°...
・Offset memo! J-, 21... Offset addition circuit, 22... Servo error signal.

Claims (1)

[Claims] an offset determination circuit that determines whether the data errors detected by the data error detection circuit are increasing or decreasing, and outputs a signal of a constant sign and a constant level according to the determination result; By reading out the offset memory circuit to store and the contents of the offset memory circuit, the servo error signal is given a certain sign,
An optical recording/reproducing device comprising an offset adding circuit that adds a certain amount of offset.