JPH0727643B2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention records information on an optical information recording medium,
The present invention relates to an optical information recording / reproducing apparatus capable of reproducing information recorded on the medium and / or erasing the information recorded on the medium, and more particularly to an auto-focus or auto-tracking pull-in circuit.

[Prior Art] Conventionally, various types of media such as a disc, a card, and a tape are known as forms of a medium for recording information using light and reading the recorded information. Among these, a card-shaped optical information recording medium (hereinafter referred to as an "optical card") is expected to be in great demand as a medium having a large recording capacity that is small and lightweight and convenient to carry.

FIG. 4 is a schematic plan view of such an optical card 101.
02 is an information recording area, 103 is an information track, 104 and 104 'are track selection areas, and 105 is a home position of a light beam spot.

The optical card 101, by scanning with a light beam that is modulated according to the recording information and is focused on a minute spot,
Information is recorded as a record bit string (information track) that can be optically detected. At this time, in order to record information accurately without causing trouble such as crossing of information tracks, the irradiation position of the light beam spot is controlled in the direction perpendicular to the scanning direction within the optical card surface (auto tracking , Hereinafter referred to as "AT"). Also, in order to irradiate the light beam as a minute spot of a stable size despite the bending and mechanical error of the optical card, control is performed in the direction perpendicular to the optical card surface (autofocusing, hereinafter referred to as "AF"). There is a need. Also, the above-mentioned AT and AF are required even during reproduction.

FIG. 5 shows a block diagram of an apparatus for recording and reproducing information on and from an optical card. 106 is a motor for driving the optical card 101 in the direction of the arrow in the figure, and 107 is a semiconductor laser or the like. A light source, 108 is a collimator lens for collimating the light from the light source 107, 109 is a beam splitter, 110 is an objective lens,
Reference numeral 111 is a tracking coil, 112 is a focusing coil, 113 and 114 are condenser lenses, 115 and 116 are photoelectric conversion elements, 117 is a tracking control circuit, and 118 is a focusing control circuit. Based on a tracking signal and a focusing signal detected by the photoelectric conversion elements 115 and 116, an electric current is applied to the tracking coil 111 and the focusing coil 112 in accordance with commands from the control circuits 117 and 118, respectively, to move the objective lens 110 to perform AT and AF. . 119 is a system controller for controlling the recording / reproducing apparatus, and 120 is a group of various control signals output from the controller. From the controller 119, 120
Other signals are also output, but not shown here.
Reference numeral 121 denotes an optical head, and 122 denotes a drive motor for moving the optical head in the direction orthogonal to the paper surface in FIG.

The light from the light source 107 is collimated by the collimator lens 108, passes through the beam splitter 109, and then is condensed by the objective lens 110 on the recording track of the optical card 101. The light reflected by the recording track is now reflected by the beam splitter 109.
Through the beam splitter 109, and they are condensed by the condenser lenses 113 and 114 on the tracking signal detecting photoelectric conversion element 115 and the focusing signal detecting photoelectric conversion element 116, respectively. The signals obtained by the photoelectric conversion elements 115, 116 are tracking control circuits 117, respectively.
The focusing control circuit 118 causes the tracking error signal and the focusing error signal to flow through the tracking coil 111 and the focusing coil 112 to move the objective lens 110, thereby performing AT and AF.

FIG. 6 is a detailed diagram of the focusing control circuit 118.

In the figure, 201 is an amplifier that amplifies the electrical focusing signal from the photoelectric conversion element 116 to an appropriate voltage.
Reference numeral 202 is a phase compensation circuit for stabilizing focusing servo control. Reference numeral 203 denotes an analog switch. One of its input terminals receives the signal from the phase compensation circuit 202 via the point B, and the other input terminal passes through point C and the output signal of the triangular wave generation circuit 206. Is entered. Reference numeral 204 denotes a driver, which receives a signal from the analog switch 203 and receives a focusing coil 112.
It is for supplying a drive signal current to. A focusing controller 205 receives the signal 120 from the system controller 119 and controls the entire focusing control circuit 118. 211 is a window comparator,
This is the comparator 207,208, the voltage is V + and V-
Of reference voltage and NOR gate 209. twenty one
Reference numeral 0 is a D flip-flop circuit to which the signal from the NOR gate 209 is input. Although FIG. 6 shows that the focusing controller 205 inputs a signal only to the analog switch 203, the focusing controller 205 also outputs other signals (not shown).

Here, the operations of auto-focus pull-in (hereinafter referred to as AF pull-in) and auto-focusing will be described with reference to FIGS. 7 and 8.

FIG. 7 shows point A (output of amplifier 201), point C (output signal of triangular wave generation circuit 206), point E (signal from NOR gate 209), point D (command of focusing controller 205) in the circuit of FIG. FIG. 4 is a time chart showing an example of signal waveforms of a signal) and a point F (command signal from the D flip-flop circuit 210 to the switch 203).

First, the signal D from the focusing controller 205
Becomes "L", the D flip-flop 210 is cleared,
The signal F becomes "L". This allows the analog switch 203
Is in a state where the point B side is open and the point C side is closed. Then, the triangular wave C output from the triangular wave generation circuit 206 causes a current to flow in the focusing coil 112,
The objective lens 110 is driven up and down. At this time, at times I and III in FIG. 7, the objective lens moves away from the optical card, and at time II, the objective lens moves closer to the optical card. In the vicinity of the focus of the objective lens on the optical card in the range of time I, the voltage at the point A, which is the focus error signal, changes to an S-shape (so-called S-shape curve) (indicated by symbol S1). In the range of time II, an S-shaped curve with reverse polarity is obtained in the range of S2.

Here, in order to perform the AF pull-in, it is necessary to change the voltage at the point A in the regions T1, T2, etc. within a substantially linear range. This is because if the focusing servo loop is closed in another area, the position control of the objective lens is not performed properly, and as a result, the AF pull-in becomes impossible.

For the above reason, the window comparator 211 is used to detect the range where the voltage change at the point A is substantially linear. With this window comparator 211, the point E becomes "H" in the range of V- [V] to V + [V], and becomes "L" in the other range (voltage at the point E in FIG. 7). See the time chart).

When the AF is pulled in here, the signal D from the focusing controller 205 is set to "H" (time t1). After that, an S-shaped curve appears in the range of S3, and at time t2 when the voltage at the point A exceeds V- [V] from the negative side, the point E which is the output of the window comparator 211 becomes "H" and D
The point F which is the output of the flip-flop 210 becomes "H".
As a result, the analog switch 203 is in a state in which the point B side is closed and the point C side is open. This closes the focusing servo loop and completes the AF pull-in.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, when there is dust or scratches on the medium surface of the optical card and a noise No occurs at point A as shown in FIG. 8, at time t3, The focusing servo loop is closed even though the voltage change at point A is not in a substantially linear region. As a result, there was a drawback that the AF pull-in failed.

[Means for Solving the Problems] An object of the present invention is to prevent the focusing servo loop from being closed in an area that is not a substantially linear area such as when there is dust or scratches on the medium surface of the optical card and to perform servo pull-in. It is an object of the present invention to provide an optical information recording / reproducing apparatus in which the focusing servo loop is closed only at the position where the optical recording should be performed.

The above-mentioned object is to provide an optical system for irradiating an information track of an optical information recording medium with a light spot, and a drive means for moving the light spot in parallel to the optical axis of the optical system or orthogonal to the information track. A signal generating means for supplying a driving signal to the driving means for reciprocating the light spot in a first direction and a second direction opposite to the first direction, and focusing or tracking error signal of the light spot. Detection circuit, a command circuit that compares the error signal with a reference value and outputs a command signal, and when a command signal is output from the command circuit, the supply of the drive signal to the drive means is stopped, and An optical information recording device that includes a switch circuit that switches so as to supply the error signal to the driving means, and that performs auto-focusing or auto-tracking pull-in. In the recorrecting device, when the error signal takes a value larger than the zero-cross point as positive, the command circuit, when the error signal goes from the positive maximum value to the zero-cross point, the reference value is positive, This is achieved by the optical information recording / reproducing apparatus, wherein the reference value is switched to a negative value when the error signal goes from the negative minimum value to the zero crossing.

[Operation] According to the present invention, by changing the reference value for comparing the error signal depending on the direction in which the light beam spot is moved, even if the medium surface of the optical card has dust or scratches, the servo pull-in can be performed without error. Will be possible.

Embodiment An embodiment of the optical information recording / reproducing apparatus of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention and is a circuit diagram showing a focusing control circuit according to an optical information recording / reproducing apparatus.

In the figure, members having the same functions as those in FIG. 6 are designated by the same reference numerals, 301 and 302 are NAND gates, and 306 is the NA.
A triangular wave generation circuit that outputs a predetermined signal to the ND gates 301 and 302, and 303 is an inverter. The triangular wave generation circuit 306 according to the present embodiment is configured to set the signal J to "H" when the objective lens is moved away from the optical card, and to output "L" when the signal is approached. Inverter 30
3 and the NAND gate 301 input the signal E to "L" only when the error signal A is on the negative side of V- [V] when the objective lens moves away, and when it approaches, the error signal A is V +. The signal E can be set to "L" only when it is on the positive side of [V]. Thus, when the moving direction of the objective lens is different, the reference values for comparing the servo error signals are changed to V + and V-.

FIG. 2 shows points A (output of amplifier 201), point C (output signal of triangular wave generation circuit 306), and point J (output to NAND gate 301 and inverter 303 of triangular wave generation circuit 306) in the focusing control circuit of FIG. Signal), G point (output signal from comparator 207), H point (output signal from comparator 208), E point (signal from NOR gate 209), D point (command signal of forcing controller 205), 7 is a time chart showing an example of signal waveforms at point F (command signal from D flip-flop circuit 210 to switch 203).

In FIG. 2, when the signal D is set to “H” at time t1,
At t2, the signal F becomes "H", and AF pull-in is completed. Also, there is dust or scratches on the medium surface of the optical card.
As shown in the figure, even when the noise No. occurs in the error signal A, the signal F does not become "H" at the time t3, and the servo loop can be closed at the time t5.
Retraction is possible.

The present invention is not limited to the above embodiment, and various modifications and applications are possible.

As described above, in the above-mentioned embodiment, the pulling-in of the auto focusing is explained, but the pulling-in of the auto tracking can be applied.

Further, the present invention can be applied not only to a device using a write-once type recording medium but also to a rewritable type device such as magneto-optical recording due to the nature of the invention. It is obvious that it can be applied to the above.

[Effects of the Invention] As described above, according to the optical information recording / reproducing apparatus of the present invention, the optical card is changed by changing the reference value for comparing the error signals depending on the direction in which the light beam spot is moved. Even if there is dust or scratches on the medium surface and noise is mixed in the error signal, the servo pull-in can be performed without error.

[Brief description of drawings]

FIG. 1 is a block diagram of a focusing control circuit according to the optical information recording / reproducing apparatus of the present invention. 2 and 3 are time charts of respective parts of the focusing control circuit embodying the present invention. FIG. 4 is a plan view of the optical card. FIG. 5 is a block diagram of an optical card recording / reproducing apparatus. FIG. 6 is a block diagram of a conventional focusing control circuit. FIG. 7 and FIG. 8 are time charts of respective parts of the conventional focusing control circuit. 116: Photoelectric conversion element 202: Phase compensation circuit 203: Switch 209: NOR gate 306: Triangular wave generation circuit 303: Inverter 301, 302: NAND gate

Claims (1)

[Claims] 1. An optical system for irradiating a light spot on an information track of an optical information recording medium, a driving means for moving the light spot in parallel with an optical axis of the optical system or orthogonal to the information track, The light spot in the first direction and in the first
Signal generating means for supplying a driving signal to the driving means for reciprocating in a second direction opposite to the direction, a detection circuit for detecting the focusing or tracking error signal of the light spot, and the error signal. A command circuit that outputs a command signal in comparison with a reference value, and when the command signal is output from the command circuit, the supply of the drive signal to the drive means is stopped and the error signal is supplied to the drive means. In an optical information recording / reproducing apparatus configured to include a switch circuit for switching and performing auto-focusing or auto-tracking, when the error signal has a value larger than a zero-cross point, the command circuit outputs the error signal. Is toward the zero cross from the positive maximum value, the reference value is positive,
An optical information recording / reproducing apparatus, characterized in that when the error signal goes from a negative minimum value to a zero cross, the reference value is switched to a negative value.