JPS58150141A - Optical information reader - Google Patents

Abstract

PURPOSE:To eliminate malfunction in information reproducing and stopping relating to a pause for operation, by putting information reproduction into a pause state while keeping an optical disc rotating and to improve operation response by constituting a titled device in such a way that an optical system is driven and controlled by a tracking servocontrol loop from one tracking position to the other tracking position. CONSTITUTION:The light beam from a disc 1 is conducted through an optical element to a photodetector 5, by which the tracking error signal, indicating the deviation between the tracks to be scanned and an optical system, as well as a focus error signal and an information signal are detected. The information signal is applied through an amplifier 6 to a decoder 7 where the eooros in the signal are detected and are corrected. This signal is fed through a DA converter 8 and an amplifier 9 to a speaker 10, from which the information is reproduced. On the other hand, the tracking error signal detected by the photodetector 5 is inputted to a tracking driving circuit 12 through a controlling circuit 11, which in turn inputs the tracking signal for correcting errors to a driving device 4, thereby controlling the driving in the tracking direction.

Description

[Detailed Description of the Invention] The present invention reproduces information by irradiating and scanning an information recording disk, a so-called optical disk, in which information such as video or audio is recorded in optical form on a thinly wound track. The present invention relates to an optical disc playback device.

Optical discs record much more information on high-density tracks than conventional mechanically traced discs, and information is reproduced by rotating these optical discs at high speeds. When bringing the disc to a pause state, once the rotation of the disc has stopped, it takes time to reach the predetermined number of revolutions in order to reach the next playback state, etc., so the responsiveness of the operation related to the pause operation Expected to worsen.

In order to eliminate the above-mentioned drawbacks, the present invention relates to a tracking servo that drives and controls an optical system so that a scanning point (beam spot) accurately scans a recording track, while the disk is rotated from a playback state to a pause state. This invention proposes an optical disc playback device that has a novel function of causing the scanning point to constantly follow the recording track corresponding to the pause position.The present invention will be described below. will be explained in detail by taking one example.

In FIG. 1, reference numeral 1 denotes an optical disk having tracks on which digitized music information, control information, etc. are recorded at high density, and is rotated by a drive motor 2 controlled by a rotation control means (not shown). .

The optical system 3 is equipped with optical elements such as a light source and a scanning objective lens.The optical system 3 is configured to be movable in the radial direction of the disk (hereinafter referred to as the tracking direction) by a tracking drive device 4, and emits light from the light source. The light beam is focused by an optical system 3, scans the recording track, and is transferred to the optical disc 1.
Read the 6-bit recording information.

Further, the light beam from the disk 1 is guided to a photodetector 5 via an optical element, and a tracking error signal, a focus error signal, and an information signal representing the deviation between the track to be scanned and the optical system 3 are detected.

The focus error signal is guided to a focus drive circuit (not shown).
Although the optical system 3 is driven by a focusing drive device (not shown), illustration and detailed explanation thereof will be omitted in this embodiment for the sake of brevity.

In addition to music information, the information signal includes an information start signal indicating the start point of one section of information, a song number signal indicating the order of information, and a time signal indicating the passage of time in one song. It will be done.

This information signal is applied to a decoder 7 via an amplifier 6,
After detecting and correcting errors in the signal, digital
Information is reproduced from a speaker 10 via an analog converter 8 and an amplifier 9.

On the other hand, the tracking error signal detected by the photodetector 5 is input to the tracking drive circuit 12 via the control circuit 11 described later, and the drive circuit inputs the tracking signal to the aforementioned drive device 4 in order to correct this error. and performs drive control in the tracking direction.

Next, referring to FIG. 2, the configuration of the control circuit 11 will be explained in relation to the CPU 13. ) FIG. 2 shows the control circuit 11, and the input terminal A is connected to the amplifier 14.
The output of the amplifier 14 is connected to the output terminal B via the switch 15 and the amplifier 16.
4 is passed through a low-pass filter 17 on one side and connected to a switch 15 via a pre-holding circuit 22 consisting of a switch 18, a resistor 19, a capacitor 20, and an operational amplifier 21, and on the other side is connected to a low-pass filter 23.
, are connected to a counter 25 via a waveform shaping circuit 24.

Each of the switches 15 and 18 has a control terminal for inputting a common control signal from the OR gate 26, and the OR gate 2
When the control signal No. 6 is at a high level, the switch is switched to the contact P side, and when it is low level, the switch is switched to the contact Q side.

Further, the input terminal of the OR gate 26 is connected to the counter output terminal on the τ side and to the control output terminal of the CPU 13 on the other side.

The waveform shaping circuit 24 generates a sinusoidal tracking waveform detected every time a track is crossed when the driving device 4 drives the optical system 3 with a predetermined driving force in the tracking direction and causes the scanning point to jump across the track. is shaped into a shaped pulse, which is fed to the counter 25.

The counter 25 counts the short pulses, and when the counted value reaches a predetermined value, outputs a high level from the output terminal.
It is also connected to the input terminal of U13.

Further, the reset terminal of the counter 25 and the control output terminal of the CPU 13 are connected, and when the control signal of the CPU 13 is at a high level, the counter 25 is in a reset state.

The control signal output of the OR gate 26 is
, 18 and also to the triangular wave generation circuit 27.

The triangular wave generating circuit 27 outputs zero when the OR gate 260 control signal is at a high level, and outputs a triangular wave voltage when the OR gate 260 control signal is at a low level.

-! The output terminal of the triangular wave generating circuit 27 is connected to the output terminal C via an amplifier 28.

Next, the operation of temporarily stopping information reproduction/playback in the above-described configuration will be described below.

First, the normal play state will be explained.

When the optical system 3 is scanning a recording track on the optical disc 1, a tracking error signal detected by the photodetector 5 is input to the input terminal A of the control circuit 11.

In addition, a high level control signal is output from the CPU 13,
The counter 25 is reset and the OR gate 2
6 will be man-powered.

Therefore, the control signal of the OR gate 26 becomes high level, the output of the triangular wave generation circuit 27 is zero, and the control signal of the switch 15 becomes high level.
+18 is switched to contact P 1M+1.

The tracking error signal input to terminal A is sent to amplifier 14.
A tracking signal corresponding to the error signal is output from the tracking drive circuit, and the drive device 4 causes the optical system 3 to follow the track to be shortened. It controls what is called a tracking servo loop.

On the other hand, the tracking error signal that has passed through the amplifier 14 passes through the low-pass filter 17, the switch 18, and flows into the capacitor 20, so that the capacitor 20 holds the residual tracking error signal value in the closed loop.

Next, in this state, when the operator performs an operation to bring the information playback to a pause state by means not shown, first the C
A low level control signal is inputted to the OR gate 26 by the PU 13, and since the output of the counter 25 is not counting, it is also at the low level k, so that the OR gate 26 outputs a low level control signal.

Along with this, switches 15 and 18 are switched to the contact Q side, and a triangular wave signal is output from the triangular wave generating circuit, and this output is given to terminal C. By switching the 1° switch 15, the tracking servo loop is opened. , by switching the switch 18, the tracking signal that has passed through the low-pass filter 17 passes through the resistor 19,
Flows to earth.

Maru - At the same time, the input of the amplifier 16 is the operational amplifier 21.
Since the capacitor 20 is connected to the output of the low-pass filter 17 and is disconnected from the output of the low-pass filter 17, the capacitor 20 holds the residual tracking error signal value in the closed loop immediately before the switch 18 is switched.

Therefore, the error signal value held by switch 15.
Simultaneously with the switching of 18, it is applied to terminal B via operational amplifier 21, switch 15, and amplifier 16, and is superimposed on the triangular wave signal of terminal C, so the triangular wave voltage changes over time with this signal value as a reference point. Accordingly, if the drive device 4 controls the drive of the optical system 3 from the inner circumference to the outer circumference of the optical disc 1 using a tracking servo loop, the optical system 3 is moved in the inner circumference direction and the scanning point is track-jumped.

Due to this movement, the waveform shaping circuit 24 converts the track jump waveform detected every time the scanning point crosses the track into a rectangular pulse, and the counter 25 counts this.

When the count value reaches a predetermined value, the counter output becomes high level, this is detected by the CPU 13, and the control output of the CPU 13 also becomes the no level.

So, or game! The control signal of 26 also becomes high level,
The switches 15 and 17 are switched to the contact P side, and the output of the triangular wave generating circuit 27 is reduced to zero to complete the track jump operation.

As mentioned above, the optical system 3 moves from the first tracking position where the trunk jump started to the second tracking position corresponding to the high level output of the counter, but by switching the switches 15 and 17, the tracking error signal is , amplifier 14, switch 15, and amplifier 16 to the tracking drive circuit, and the scanning point follows the movement of the recording track from the second tracking position, again by the servo loop.

Also, the capacitor 2o in the prehold circuit 22 is charged again with the residual tracking signal in the closed loop.

If the pause operation is not released, the CPU 13 detects the first tracking position in the drive control of the servo loop, and the optical system 3 performs the same operation as described above between the first tracking position and the second tracking position. repetition,
During this time, the decoder 7 receives a command from C)) U13 and temporarily stops the information reproduction from the speaker 1o.
is commanded to reproduce information from the corresponding recording track during the above-mentioned pause operation, and also always sends a high-level control signal to the OR gate 26 so as not to perform a track jump even when the first tracking position is reached. By giving this, the play state can be established by the closed loop state described above.

As described above, according to the present invention, there is provided an apparatus for reproducing information by optically scanning a recording track on an information recording disk, the optical system deflecting a light beam from a light source and focusing it on the recording track. a photodetector that optically detects the light beam from the recording track; a tracking servo loop that drives and controls the optical system in the radial direction of the recording disk according to the scanning error of the scanning point; control means for jumping a predetermined number of tracks in the radial direction, the optical system opening the tracking servo loop from the first tracking position to the second tracking position in connection with an operation to temporarily stop information reproduction; Although the optical system is driven by the control means in a state where Information playback is paused while the disk is still rotating, and even if the disk is eccentric, the servo loop follows the corresponding recording trunk.
It is an object of the present invention to provide an optical information reading and reproducing device which is free from malfunctions of information reproduction and stop related to the time stop 1-1 operation and has good operational response.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of this embodiment, and FIG. 2 is a circuit diagram explaining the control circuit in FIG. 1. Explanation of symbols

Claims (1)

[Claims] A device for optically scanning a recording track on an information recording disk [2] for reproducing information, comprising: an optical system that deflects a light beam from a light source and focuses it on the recording track; a tracking servo loop that drives and controls the optical system in the radial direction of the recording disk according to the scanning error of the scanning point, and a tracking servo loop that causes the scanning point to jump a predetermined number of ranks in the radial direction. and a control means, in which the optical system opens the tracking servo loop from the first tracking position to the second tracking position in connection with an operation to temporarily stop information reproduction. An optical information reading device characterized in that, when driven, the optical system is configured to be driven and controlled from the second tracking position to the first tracking position by the dragging servo loop.