JP2798246B2 - Optical disk drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal source for activating a focus servo of an optical disk device. [Prior Art] FIG. 2 is a configuration diagram of a focus servo system circuit of a conventional optical disk device disclosed in, for example, Japanese Patent Application Laid-Open No. 60-263335, wherein 1 is an optical disk medium, and 2 is this optical disk medium. 1, an objective lens for focusing a light spot,
Reference numeral 3 denotes an optical disk medium 1 in which a light spot focused by the objective lens 2 is reflected by the optical disk medium 1.
Position detecting means 4 for converting a relative distance between the object lens 2 and the objective lens 2 into a detection signal 3a.
The determination means 5 for determining whether or not there is a reference numeral 5 indicates that when the objective lens 2 is out of the focus servo operation area, for example, when the power is turned on, the objective lens 2 is forcibly moved to a position where the objective lens 2 becomes the focus servo operation area. A moving means for actually moving the objective lens 2 by an output signal 5a of the controlling means 5;
7 is when the objective lens 2 is out of the focus servo area.
First signal generating means for generating a low-frequency signal for moving the objective lens 2; second signal generating means 8 for generating an electric signal having a higher frequency than the signal generated by the first signal generating means 7; Reference numeral 9 denotes a superimposing means for superimposing the respective signals generated by the first signal generating means 7 and the second signal generating means 8. The conventional optical disk device is configured as described above, and its operation will be described below. When the objective lens 2 is out of the operation area of the focus servo system circuit, for example, when the power is turned on in the optical disk device, the objective lens 2 is forcibly moved in the optical axis direction by the low frequency electric signal of the first signal generating means 7. Will be moved through. As the objective lens 2 moves, the relative position between the optical disk medium 1 and the objective lens 2 is detected by the position detecting means 3, and a detection signal 3a is output. The detection signal of the position detecting means 3
According to 3a, the determination means 4 determines that the relative position between the optical disk medium 1 and the objective lens 2 has entered the operation area of the focus servo system circuit. In this way, when the determination unit 4 determines that the relative position between the optical disk medium 1 and the objective lens 2 is within the operation area of the focus servo system circuit, the control unit 5 controls the objective lens 2 by the first signal generation unit 7 described above. Is stopped, and the objective lens 2 is moved following the detection signal 3a from the position detecting means 3.
Moves to the normal focus servo operation. Therefore, the second signal generating means 8 generates a high-frequency signal higher than the low-frequency signal generated by the first signal generating means 7, and the superimposing means 9 generates both signals 7a and 8a from the respective signal generating means 7 and 8. Are superimposed on each other and the objective lens 2 is driven, so that the servo pull-in area can be easily detected. Next, FIG. 3B shows the output signal waveform of the first signal generating means 7 in FIG. 2 described above. In order to shorten the activation time of the focus servo, it is necessary to move the objective lens 2 up to the focus pull-in level quickly. Retraction becomes unstable. Therefore, the signal frequency of the first signal generating means 7 becomes lower than a certain frequency due to the focus servo characteristic. [Problems to be Solved by the Invention] Since the conventional optical disk apparatus is configured as described above, two signal generating means and two signals from these signal generating means are required to activate the focus servo. There has been a problem that it is necessary to have a superimposing means for superimposing a signal, and it is not possible to shorten the start time of the focus servo by a certain amount or more. The present invention has been made to solve the above problems, and in particular, two signal generating means and a superimposing means of the two signals which have been conventionally used are combined into one signal by using a CPU. It is an object of the present invention to provide an optical disk device that can be used as a source and that can obtain an optimal focus servo pull-in signal and shorten the focus servo activation time. [Means for Solving the Problems] An optical disc apparatus according to the present invention performs an automatic focus pull-in for moving an objective lens facing an optical disc in an optical axis direction to pull the objective lens into an operation area of a focus servo system circuit. In the optical disc device, an arbitrary function generator for operating a moving unit for forcibly moving the objective lens in the optical axis direction, and a memory, a CPU, and a D / A for configuring the arbitrary function generator Conversion means, the CPU sets an output voltage code by the signal from the memory in which a signal at the time of focus servo activation is preliminarily incorporated, and the output voltage code is set to the D /
The objective lens is rapidly moved to the vicinity of the operation area by applying the output signal, which rises rapidly at the time of starting the focus servo, to the moving means while obtaining the output signal by D / A conversion by the A converting means. The output signal is configured to move the objective lens slowly near the pull-in point of the focus servo, and further includes a detection signal of position detection means for detecting a relative position between the optical disc and the objective lens. Is applied to the moving means via the judgment means and the control means. [Operation] In the optical disk device of the present invention, since the generator of the signal applied to the moving means is an arbitrary function generator consisting of a CPU, a memory, and a D / A conversion means, the CPU receives an arbitrary function based on information from the memory. An arbitrary output voltage code can be output at a time, an optimal signal is generated with a simple configuration by performing a rapid movement and an arbitrary deceleration movement of the objective lens, and a stable focus servo activation is obtained, The startup time of the focus servo can be reduced. [Embodiment] An embodiment of an optical disk device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a focus servo system circuit of an optical disk apparatus according to the present invention, and FIG. 3A is a waveform diagram showing a focus servo pull-in signal. Objective lens that focuses the light spot of
Reference numeral 3 denotes a position detecting means for converting the relative distance between the optical disk medium 1 and the objective lens 2 into a detection signal 3a from the light reflected by the optical disk medium 1 by the light spot focused by the objective lens 2; Determination means for determining whether or not the objective lens 2 is in the focus servo operation area based on the detection signal 3a obtained by the detection means 3;
When the objective lens 2 is out of the focus servo operation area, such as when the power is turned on, the objective lens 2 is forcibly moved via the moving means 6 described below until the position of the objective lens 2 becomes the focus servo operation area. A moving means for actually moving the objective lens 2 based on an output signal 5a of the controlling means 5, a memory 10 for storing a signal at the time of starting a focus servo, and a memory 11 for storing the signal.
The CPU 12 generates a focus servo activation signal 11a as a digital output based on the information 10a from 10 and converts the focus servo activation signal 11a into an analog signal and applies a D / A signal to the moving means 6 described above. Conversion means. Therefore, the above-described CPU 11 can set an arbitrary output voltage code at an arbitrary time based on the information in the memory 10, and can convert the output voltage code into an analog voltage by the D / A converter 12, and Memory 10,
An arbitrary function generator 13 is constituted by the CPU 11 and the D / A conversion means 12. The optical disk device according to the present invention is configured as described above, and its operation will be described below. Output signal of the arbitrary function generator 13 configured as described above
Since 12a can set an arbitrary output voltage code at an arbitrary time according to information 10a from the memory 10, it quickly rises as shown in FIG. By applying a signal to the moving means 6, the objective lens 2 is quickly moved to the vicinity of the operation area of the circuit of the focus servo system, and further, is moved slowly near the focus servo pull-in point. be able to. The CPU 11 and the memory 10 described above are provided in the optical disk device. [Effects of the Invention] As described above, according to the present invention, the signal source for starting the focus servo is set by the CPU to an arbitrary output voltage code according to the signal from the memory containing the signal at the time of starting the focus servo. It is composed of an arbitrary function generator consisting of a memory, CPU and D / A conversion means so that it is possible to arbitrarily generate a more optimal signal with a simple configuration and achieve stable focus servo. And start time of the focus servo can be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a focus servo system circuit of an optical disk device according to an embodiment of the present invention, FIG. 2 is a block diagram of a focus servo system circuit of a conventional optical disk device,
FIG. 3A is a signal waveform diagram of a focus servo circuit according to the present invention, and FIG. 3B is a signal waveform diagram of a conventional focus servo circuit. 1 is an optical disk medium, 2 is an objective lens, 3 is a position detecting means, 4 is a judging means, 5 is a controlling means, 6 is a moving means, 10 is a memory, 11 is a CPU, 12 is a D / A converting means, and 13 is arbitrary It is a function generator. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-76032 (JP, A) JP-A-63-138531 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 7/085

Claims (1)

(57) [Claims] In an optical disc device in which an objective lens facing an optical disc is moved in an optical axis direction to perform automatic focus pull-in for drawing into an operation area of a focus servo system circuit, the objective lens is forcibly moved in the optical axis direction. An arbitrary function generator for operating the moving means for the memory, a memory for configuring the arbitrary function generator, a CPU and D / A conversion means, and the memory in which a signal at the time of starting a focus servo is previously stored. The CPU sets an output voltage code according to the signal from
The output means is obtained by D / A conversion by the conversion means, and the objective lens is rapidly moved to the vicinity of the operation area by applying the output signal which rises rapidly at the time of starting the focus servo to the movement means. An optical disk device, wherein the output signal is configured to move the objective lens slowly near a pull-in point of a focus servo. 2. 2. The optical disk according to claim 1, wherein a detection signal of a position detection unit for detecting a relative position between the optical disk and the objective lens is applied to the moving unit via a determination unit and a control unit. apparatus.