JPH04311825A - Optical memory device - Google Patents

Abstract

PURPOSE:To improve reliability by detecting the central value of the amplitude of a track error signal, feeding back through a track offset control circuit, controlling an offset quantity and automating the offset adjustment. CONSTITUTION:A track error signal 105 is inputted to a terminal 104, and while the track servo is not loaded, a central value detecting circuit 102 detects a central value 108 of the amplitude of a track error signal. By receiving the central value 108, a track offset circuit 103 decides the offset quantity added to an adder 101. The adder 101 adds and outputs a signal 109 to give the offset voltage to the signal 105, and a track error signal 106 is outputted to a terminal 107.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to track servo offset adjustment of an optical memory device.

0002

2. Description of the Related Art In conventional optical memory devices, offset adjustment of a track servo is generally performed using a volume when assembling and adjusting the device. Adjustment is performed so that the track servo is applied at the center of the amplitude of the track error signal.

FIG. 4 shows a track servo offset adjustment circuit diagram in a conventional optical memory device. A track error signal 205 is input from the terminal 204 . An operational amplifier 201 adds an offset voltage to the track error signal, and a track error signal 206 to which the offset has been added is input to a drive circuit 202 . The offset voltage at this time is adjusted using the volume 203. A signal 207 for driving the track actuator is output from the terminal 208.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, offset adjustment for track errors is only performed once during assembly and adjustment of the device. If this occurs, the track servo will not work at the center of the track, and recording or playback will not be possible at the center of the track. If this condition worsens, there will be a problem that the error rate will increase during recording and reproduction exchanges with other optical memory devices, reliability will decrease, and compatibility between devices will not be maintained. SUMMARY OF THE INVENTION The present invention aims to solve these problems and to provide a highly reliable optical memory device by automating the adjustment of track servo offset.

[0005]

[Means for Solving the Problems] The optical memory device of the present invention includes a focus servo for always focusing the light focused by an optical head using a semiconductor laser or the like as a light source on an optical recording medium, In an optical memory device that performs track servo and records/reproduces information based on a track error signal obtained by detecting a deviation between the focal point and a guide groove on the optical recording medium, a) an offset voltage is applied to the track error signal; an adder circuit for adding b)
c) a center value detection circuit that detects the center of the amplitude of the track error signal; and c) a track offset control circuit that controls the offset amount of the track servo system based on the value output from the center value detection circuit. do.

[0006]

EXAMPLES (Example 1) Examples of the present invention will be described below based on the drawings. FIG. 1 is a block diagram of an optical memory device according to the present invention. The track error signal 10 is connected to the terminal 104.
5 enters. When the track servo is not applied, the center value detection circuit 102 outputs the track error signal 10.
The center value of the amplitude of 6 is detected and output. In response to the amplitude center value 108 of this signal, the track offset control circuit 10
In step 3, the amount of offset to be added to the adder circuit 101 is determined. The adder circuit adds a signal 109 giving an offset voltage to the track error signal 105 and outputs the result, and this track error signal 106 is output to a terminal 107 .

FIG. 2 shows a specific circuit diagram as an embodiment of the present invention. A portion 101 surrounded by a dotted line in the figure is an adder circuit,
102 is a center value detection circuit, and 103 is a track offset control circuit. First, the addition circuit 101 will be explained. This circuit consists of an operational amplifier 113 and resistors 110 and 111.
, 112 and track error signal 105
This circuit adds and amplifies the signal 109 and the signal 109 that provides an offset voltage. The weighting of each signal in addition is done by resistors 110 and 111, and the amplification factor is by resistor 1.
10, 111 and the resistance 112.

Next, the center value detection circuit 102 will be explained. FIG. 3 is a diagram showing how the track error signal is offset.
By detecting the peak voltage 134 and bottom voltage 135 of 6 and averaging them, the center amplitude value 108 of the signal is determined.
This is a circuit that searches for . The details will be explained below. First, operational amplifiers 114 and 118, a diode 115, and a capacitor 116 constitute a peak hold circuit. The resistor 117 is for determining the hold time. Further, operational amplifiers 119 and 123, a diode 120, and a capacitor 121 constitute a bottom hold circuit. The resistor 122 is used to determine the hold time, similar to the peak hold circuit. The operational amplifier 127 and the resistors 124, 125, and 126 are the adder circuit mentioned above, and after adding the peak voltage and the bottom voltage, 1/
By doubling, the center amplitude value 108 of the signal is obtained. For this purpose, the ratio of resistors 124, 125, and 126 is 2:
The ratio is 2:1.

The track offset control circuit 103 is a CP
It is composed of U130, A/D converter 128, and D/A converter 132. The CPU 130 controls ON/OFF of the focus servo and track servo, and outputs a digital signal 131 that determines the offset amount when the focus servo is ON and the track servo is OFF. The D/A converter 132 converts this digital signal 131 into an analog signal and outputs it to the adding circuit 101. Further, the A/D converter converts the amplitude center value 108 of the signal from an analog signal to a digital signal 129. The CPU 130 that received the digital signal receives the digital signal 12.
9 and the reference level 133 of the operational amplifier 113, and if these values are different, the digital signal 131 with an offset added thereto to compensate for the difference is sent again.

By repeating the above steps, the offset of the track error signal is automatically adjusted, and the track error signal 106 is output from the terminal 107. Also, CPU13
0 monitors the ON/OFF of the focus servo and track servo as described above, so the offset level is stabilized and after the track servo is turned on following the focus servo, the offset amount remains constant without adjustment. Control is performed so that the track servo is applied to the position.

If the above-described operation is performed every time a disk is replaced, it is possible to adjust the track offset in response to changes in the device over time and changes in the surrounding environment. Additionally, compatibility between devices is maintained. If more detailed adjustment is required, the CPU 130 may control the offset adjustment to be performed at regular intervals.

0012

As described above, according to the present invention, the offset amount of the track servo is automatically adjusted without being influenced by changes over time or environmental changes, so that the reliability of the optical memory device is improved. Furthermore, since there is no need to adjust the offset of the track servo during assembly and adjustment, the hassle of adjustment is relieved and the assembly time of the device can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical memory device of the present invention.

FIG. 2 is a circuit diagram of an embodiment of the optical memory device of the present invention.

FIG. 3 is a diagram showing an offset state of a track error signal according to the present invention.

FIG. 4 is a circuit diagram of a track offset adjustment section of a conventional optical memory device.

[Explanation of symbols]

101 Addition circuit 102 Center value detection circuit 103 Track offset control circuit 108 Signal amplitude center value 128 A/D converter 130 CPU 132 D/A converter 133 Reference level

Claims (1)

[Claims] 1. A focus servo is provided for always focusing the light focused by an optical head using a semiconductor laser or the like as a light source on an optical recording medium, and the focus servo is provided with a guide groove on the optical recording medium and the focal point. In an optical memory device that performs track servo and records/reproduces information based on a track error signal obtained by detecting a deviation from the track error signal, the optical memory device includes: a) an adder circuit for adding an offset voltage to the track error signal; and b) c) a center value detection circuit that detects the center of the amplitude of the track error signal; and c) a track offset control circuit that controls the offset amount of the track servo system based on the value output from the center value detection circuit. optical memory device.