JPH11353654A - Optical information recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a mean level of light emission power in a reproducing pulse section and to stabilize recording by synchronizing a recording signal with an intermittent pulse signal in the reproducing pulse section of the recording signal. SOLUTION: A reproducing clock formation circuit 704 forms a reproducing clock signal RCLK to intermittently light emits a semiconductor laser at prescribed frequency and duty at a reproducing time. The reproducing clock signal RCLK is inputted to a frequency divider circuit 101, and its output signal is inputted to an MPU 701 as a recording clock signal WCLK. The recording clock signal WCLK is used as a reference clock when the MPU 701 generates the recording signal WD to be supplied to a parallel/serial converter in the MPU 701. The reproducing clock signal RCLK is synchronized with the phase of the recording clock signal being the reference clock of the recording signal to fix a mean output of a gain switch circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording / reproducing apparatus for optically recording information on an information recording medium,
In particular, the present invention relates to an optical information recording device of a single light source type.

[0002]

2. Description of the Related Art Conventionally, various types of recording media for optically recording information or reproducing recorded information, such as a disk, a card, and a tape, are known. Among these recording media, there are those that can be recorded and reproduced and those that can only be reproduced. In recording information on a recordable recording medium, information is recorded as an optically detectable information pit row by scanning a light beam in the form of a minute spot modulated according to the recording information on an information track.

When information is reproduced from a recording medium, an information pit array of an information track is scanned with a light spot having a constant power enough to prevent recording on the recording medium, and reflected light or transmitted light from the recording medium is read. Is detected, and the recorded information is reproduced based on the obtained detection signal. An optical head used for recording and reproducing information on and from such a recording medium is configured to be movable relative to the recording medium in the information track direction and in the direction across the track. The spot is accessed to a desired information track, and the information track is scanned.

An optical head is provided with a focusing lens for narrowing a light beam, and an objective lens is used as this lens. Such an objective lens is held so that the optical head body can be independently moved in the optical axis direction (focus direction) and the direction perpendicular to the information track of the recording medium (tracking direction). Such holding of the objective lens is generally performed via an elastic member, and the movement of the objective lens in the focusing and tracking directions is generally driven by an actuator utilizing magnetic interaction.

FIG. 4 is a schematic plan view of a write-once optical card. On the information recording surface of the optical card 401, a number of information tracks 402 are arranged in parallel to the LF direction. On the information recording surface of the optical card 401, a home position 403 serving as a reference position for accessing the information track 402 is provided. The information tracks 402 are 402-1, 40 in order from the one closer to the home position 403.
2-2, 402-3...

As shown in FIG. 5, a tracking track 504 is located adjacent to each of these information tracks 402.
-1, 504-2, 504-3... These tracking tracks are used as a guide for auto tracking (hereinafter abbreviated as AT) for controlling the light spot so as not to deviate from the target information track when scanning the light spot during information recording and reproduction.

Such AT control detects a deviation (AT error) of a light spot from an information track in an optical head, and negatively feeds this detection information back to a tracking actuator that drives an objective lens in a tracking direction. It is controlled by a control circuit. That is, by moving the objective lens with respect to the optical head body in the tracking direction (D direction), control is performed so that the light spot does not deviate from the target information track.

In addition, when scanning an information track with an optical spot at the time of information recording and reproduction, an auto lens with respect to an objective lens is formed in order to form (focus) a light beam on the optical card surface into a spot of an appropriate size. Focus (hereinafter, AF
) Is performed. In such AF control, a deviation (AF error) of a light spot from an in-focus state in an optical head is detected, and this detection signal is negatively fed back to a focus actuator for moving an objective lens along an optical axis direction, and the By moving the objective lens with respect to the head body in the focus direction, the light spot is controlled to be focused on the optical card surface (recording layer).

Here, in FIG. 5, S1, S2, S3,
S4, S5, S6 and S7 indicate light spots irradiated on the information tracks of the optical card, and among them, the light spots of S1 and S5 partially applied to the tracking tracks 504-2 and 504-3 are used. AT control is performed. Also, AF control, creation of information pits at the time of recording, and reading of information pits at the time of reproduction are performed using the light spot of S3, and verification of the information pit immediately after recording is performed by the light spots of S2 and S4. In addition, information pits are read out at the time of reproduction with the light spots of S6 and S7. In the drawing, 505-1 and 505-2 are light spots S.
3 and the information pit 505-
Numeral 1 indicates that the recording was performed by scanning the light spot in the L direction, and information pit 505-2 was performed by scanning the light spot in the F direction.

FIG. 6 is a block diagram showing an optical information recording / reproducing apparatus using an optical card as an information recording medium. In FIG. 6, reference numeral 221 denotes a semiconductor laser as a light source, which emits 830 nm wavelength laser light polarized in a direction perpendicular to the track. Reference numeral 223 denotes a collimator lens, 250 denotes a diffraction grating having a two-dimensional grating for splitting a light beam, and 226 denotes a polarization beam splitter. 227 is a quarter-wave plate, 228 is an objective lens, 229 is a spherical lens, 230 is a cylindrical lens, and 231 is a photodetector.

As shown in FIG. 10, the photodetector 231
Light receiving elements 231a, 231b, 231c, 231
e, 231f, 231g and one 4 divided into four
It is composed of a divided light receiving element 231d. Each of the above optical elements is integrated as an optical head, and is configured to be able to access a desired information track of the optical card 401. Reference numeral 261 denotes a laser driver (hereinafter, referred to as an LD driver) that switches the power of the semiconductor laser 221 between the recording light power and the reproduction light power according to the recording signal WD. When light is emitted with the reproduction light power, intermittent light emission is performed at a predetermined frequency and duty to reduce the effect of astigmatism caused by the difference in the emission power of the semiconductor laser. Reference numeral 262 denotes a recording signal creation circuit that controls each unit of the optical information recording / reproducing device.

Here, when information is recorded on the optical card 401 by the optical head, a recording level current is supplied to the semiconductor laser 221 by the LD driver 261 in accordance with a recording command from the recording signal creation circuit 262. When reproducing information, the LD driver 261 supplies a current of a reproduction level to the semiconductor laser 221 so as to emit light intermittently at a predetermined frequency and duty according to a reproduction command from the recording signal creation circuit 262. Thus, the semiconductor laser 221 is driven, and the semiconductor laser 221 is driven.
Is emitted as a divergent light beam and enters the collimator lens 223. Then, the collimator lens 223
After being collimated by the diffraction grating 250, the light is incident on the two-dimensional diffraction grating 250, and seven effective light beams (0
(First order diffracted light in three directions).

FIG. 7 is a schematic diagram of a diffraction grating 250 used in the optical information recording / reproducing apparatus. In the drawing, reference numeral 250a denotes an AT diffraction grating forming unit for generating an AT control light beam which becomes spots S1 and S5, and reference numeral 250b denotes a spot S2.
And a diffraction grating forming unit for DV for generating a direct-verifying light beam to be S4 and S4.
An RFR / RFL diffraction grating forming unit 301 for generating an information reproduction light beam 7 is an incident light beam. By the way, the diffraction angle θn of the diffracted light is determined by θn = n · λ / d (where n is the order) from the grating pitch d and the wavelength λ of the incident light flux. The diffraction direction is determined by the inclination δ of the grating with respect to the incident light beam, and the direction is substantially perpendicular to the grating. The diffracted light beam and the zero-order light beam that are diffracted are irradiated as light spots S1 to S7 on an optical card via an objective lens or the like as shown in FIG.

The light power ratio of each spot is the recording light power at which the recording spot S3 (zero-order diffracted light) generates recording pits when the recording light is emitted, and the light power of the spots other than S3 is the light power at which no recording pit is generated. And the pulse width is determined. The light power ratio of each spot can be determined by setting the diffraction efficiency of each diffraction grating. That is, the light power of the light spot S3 is the sum of the zero-order light of each diffraction grating, and the light power of the other spots is set by the diffraction efficiency of the diffraction grating that generates the spot.

The seven split light beams enter the polarization beam splitter 226 as a P-polarized light beam, pass through the light beam, enter the quarter-wave plate 227, and pass through the quarter-wave plate 227. Converted to circularly polarized light. The seven luminous fluxes converted into circularly polarized light are narrowed down to a minute light spot by the objective lens 228, and are focused on the optical card 401. The focused light is used as the small light spots S1, S2 and S6 in FIG.
(+ 1st-order diffracted light), S3 (0th-order diffracted light), S4, S5, and S7 (-1st-order diffracted light). The light spot S3 is used for recording, reproduction, and AF control as described above.
Is used for AT control, S2 and S4 are used for verifying information pits immediately after recording, and S6 and S7 are used for reproducing information on an information track adjacent to an information track irradiated with recording light.

As shown in FIG. 5, the spot positions on the optical card 401 are such that the light spots S1 and S5 are located on the adjacent tracking tracks, the spots S2, S3 and S4 are located on the information track 402-2 between the tracking tracks. S6 is located on the information track 402-1 adjacent to the information track 402-2, and the spot S7 is located on the information track 402-3 adjacent to the information track 402-2. The light spots S2 and S4 for verification are located before and after the light spot S3. Thus, the light spot is irradiated on the optical card 1, and a part of the light spot is reflected on the optical card surface and enters the objective lens 228. This reflected light passes through the objective lens 228 again to become a parallel light flux,
Further, by transmitting through the quarter-wave plate 227, the light beam is converted into a light beam whose polarization direction is rotated by 90 ° from that at the time of incidence. Then, the light enters the polarization beam splitter 226 as an S-polarized beam, and is reflected toward the detection optical system by its characteristics.
It is separated from the incident light beam from the semiconductor laser 221.

The detection optical system includes a spherical lens 229, a cylindrical lens 230, and a photodetector 231. AF control by the astigmatism method is performed by a combination of the spherical lens 229 and the cylindrical lens 230. The seven light beams reflected from the optical card 401 are detected by a photodetector 231 including a plurality of light receiving elements.
Each light receiving signal of the plurality of light receiving elements of the photodetector 231 is recorded /
The signal is sent to the reproduction gain switching circuit 265. The recording / reproducing gain switching circuit 265 is a circuit for correcting the fluctuation of the signal level of each light receiving element caused by the modulation of the recording light spot, that is, the change of the recording power and the reproducing power, and keeping it at a substantially constant signal level. . That is, the recording signal creation circuit 26
The gain for amplifying the signal is switched in accordance with the recording / reproducing gain switching signal output from the second unit 2 so that the signal of each light receiving element is maintained at a constant signal level.
Here, the meaning of keeping the signal of each light receiving element at a constant signal level means that the reflectance becomes the same level when the light reflected from the same surface is detected.
Therefore, an accurate signal level can be obtained according to the reflectance.

The output signal of the recording / reproduction gain switching circuit 265 is sent to an addition / subtraction circuit 263, a subtraction circuit 264, a selection switch 266, and a recording signal creation circuit 262. The addition and subtraction circuit 263 includes an AF
Control signal (focus error signal) and information reproduction signal R
F, an AT control signal (tracking error signal) is generated in the subtraction circuit 264, and the recording signal generation circuit 2
Sent to 62. The selection switch 266 selects a verifying signal according to a moving direction signal (a signal indicating the scanning direction of the light spot) from the recording signal generation circuit 262, as described later. The recording signal creation circuit 262 generates an AF control signal,
A focus actuator and a tracking actuator (not shown) are driven based on the AT control signal, and the objective lens 228 is displaced in a focus direction and a tracking direction, thereby performing focus control and tracking control. In reproducing information, the recording signal generation circuit 2
At 62, the information reproduction signal RF and RFR, RFL are respectively subjected to predetermined signal processing to generate reproduction data. Further, at the time of recording information, the verifying signal selected by the selection switch 266 is binarized, and this is compared with the recording signal to perform verification at the same time as recording, that is, direct verification.

FIG. 8 is a detailed diagram of the recording signal creation circuit 262. 8, first, the recording signal creation circuit 262
Is composed of an MPU 701, a recording clock generation circuit 702, and a reproduction clock generation circuit 704. The host computer 703 is a higher-level control device. MPU70
1 mainly controls hardware such as a scanning motor and AT and AF actuators, and a host computer 703.
The recording area signal WZ is generated based on the format information for dividing one track from a plurality of sectors into a plurality of sectors for recording and the pulse signal ENC indicating the position information of an encoder attached to a scanning motor (not shown). .

The MPU 701 generates a recording signal WD corresponding to an information pit string in accordance with format information and recording data from the host computer 703, and outputs the recording signal WD with reference to the recording area signal WZ so that it can be recorded in a desired sector. I do. At the time of reproduction, the recording signal WD is off. Recording clock signal W generated by recording clock generation circuit 702
CLK is used as a reference clock when the MPU 701 generates the recording signal WD, and is input to the parallel / serial converter in the MPU 701. The reproduction clock signal RCLK generated by the reproduction clock generation circuit 704 is used as a clock for causing the semiconductor laser 221 to emit light intermittently at a predetermined frequency and duty during reproduction.
Although not shown in FIG. 8, the information reproduction signal obtained at the time of reproduction is subjected to predetermined signal processing to generate reproduction data, which is transferred to the host computer 703, or obtained at the same time as recording at the time of recording. A circuit is provided for binarizing the verifying signal, comparing the signal with a recording signal, and performing verification at the same time as recording, that is, direct verification.

FIG. 9 is a specific circuit configuration diagram of the LD driver 261. 9, an LD driver 261 supplies a current source 801 for outputting recording light power, a current source 802 for outputting reproduction light power, and an output current Iw of the current source 801 to the semiconductor laser 221 in accordance with a recording signal WD. A switch 803 for supplying, an AND gate 805 for calculating a logical product of an output of the inverter 806 for inverting the logic of the recording signal WD, and a switch for supplying the output current Ir of the current source 802 to the semiconductor laser 221 according to the output signal of the AND gate 805. 804. Semiconductor laser 221
Is the cathode ground, and RCK is the output of the reproduced clock generation circuit 704.

When the information is reproduced, the switch 803 is turned off because the recording signal WD is off, and the current source 80 is turned off.
1 is not supplied to the semiconductor laser 221. On the other hand, when the recording signal WD is off, the inverter 806
Is turned on, the reproduced clock RCLK is output to the output of the AND gate 805. Then, the switch 804 is turned on only during the ON period determined by the predetermined frequency and the duty of the reproduction clock RCLK, and the current source 8
02 is supplied to the semiconductor laser 221.
The semiconductor laser 221 emits light intermittently with the reproduction light power Pr corresponding to the output current Ir.

In recording information, the switch 803 is turned on because the recording signal WD is turned on, and the output current Iw of the current source 801 is supplied to the semiconductor laser 221. On the other hand, when the recording signal WD is on, the output of the inverter 806 is off, and the output of the AND gate 805 is also off. Therefore, the switch 804 is turned off, and the current source 80
The second output current Ir is not supplied to the semiconductor laser 221. That is, only the output current Iw of the current source 801 is supplied to the semiconductor laser 221, and the semiconductor laser 221 emits light with the recording light power Pw corresponding to the output current Iw. Although not shown in FIG. 9, in order to further stabilize the optical power for reproduction and recording, APC (automatic power control) for monitoring a part of the optical output of the semiconductor laser 221 and applying feedback is generally performed.

FIG. 10 is a circuit diagram showing in detail a signal processing circuit of the optical information recording / reproducing apparatus. In FIG. 10, 2
31 is a photodetector of FIG. The light spot on the light receiving surface of each light receiving element indicates the reflected light of the light spot applied to the information track in FIG. Light spot S for AT control
The reflected light of S1 and S5 is received by the light receiving elements 231c and 231e, the reflected light of the light spot S3 for AF control, recording and reproduction is received by the four-divided light receiving element 231d, and further the light spot S2 for verification and The reflected light of S4 is light receiving element 2
Light is received at 31b and 231f. Furthermore, RFR, REL
The reflected light from the light spots S6 and S7 for
a and 231g are received. Output signals from the light receiving elements 231b to 231f of the photodetector 231 are input to the respective gain switching circuits 265b to 265f of the recording / reproduction gain switching circuit 265.

That is, the recording / reproduction gain switching circuit 265 is composed of eight gain switching circuits 265b to 265f, and the output signal of the light receiving element 231b is applied to the gain switching circuit 26.
5b, the output signal of the light receiving element 231c is
65c, the output signals of the four light receiving element pieces of the light receiving element 231d divided into four parts are gain switching circuits 265d1 to 265d4.
Respectively. The output signal of the light receiving element 231e is input to the gain switching circuit 265e, and the output signal of the light receiving element 231f is input to the gain switching circuit 265f. The gain switching circuits 265b to 265f switch the gain for amplifying the signal in accordance with the recording power and the reproduction power of the semiconductor laser 221 as described above, and the output signals of the light receiving elements 231b to 231f are changed by the respective gain switching circuits. Is maintained at a constant signal level by the gain switching operation.

Next, the output signal of the light receiving element 231a is input to the gain circuit 265a, and the output signal of the light receiving element 231g is input to the gain circuit 265g. These two light receiving elements use the signals only at the time of reproduction and are not used at the time of recording, so that the gain switching is unnecessary, and only the gain corresponding to the reproduction power is obtained. Here, the recording / reproduction gain switching signal uses a recording signal WD which is turned on / off in accordance with a pit to be recorded.

FIG. 11 shows gain switching circuits 265b to 265.
The circuit configuration of f is shown. In the following description, the output voltage / input current (that is, feedback resistance) is expressed as a gain. First, a series circuit of a feedback resistor Rr, which determines a gain at the time of reproduction, an analog switch 1004 switched by a recording / reproduction gain switching signal, and a feedback resistor Rw is connected in parallel between the (−) input and the output of the operational amplifier 1001. Also,
A capacitor Cr is connected in parallel with the feedback resistor Rr, and a capacitor Cw is connected in parallel with the feedback resistor Rw. The recording / reproduction gain switching signal uses a recording signal WD that is turned on and off in accordance with a pit to be recorded.

When the recording / reproduction gain switching signal is turned on, the analog switch 1004 is turned on, and the parallel resistance of the feedback resistor Rr and the feedback resistor Rw is set to the gain at the time of recording. The feedback resistor Rr is determined to have an appropriate gain so that the output of the operational amplifier is not saturated with the light receiving element signal during reproduction. Further, the gain at the time of recording, that is, the parallel resistance of the feedback resistor Rr and the feedback resistor Rw is determined such that the output of the operational amplifier 1001 at the time of recording has the same magnitude as the average output of the operational amplifier 1001 at the time of reproduction. For example, when the ratio between the average value of the reproduction light and the recording light is 1: 100, the gain at the time of reproduction and the gain at the time of recording are set to 100: 1. The capacitors Cr and Cw function as low-pass filters at the time of reproduction and recording, respectively, and at the time of reproduction, smooth out intermittent pulses to create a smooth signal.

FIG. 12 shows RFR and RFL gain circuits 265a and 265a for amplifying the outputs of the light receiving elements 231a and 231g.
It is a figure showing the circuit composition of 65g. A feedback resistor Rf is connected between the (−) input and output of the operational amplifier 901 to determine an appropriate gain that does not saturate the output of the operational amplifier with a light receiving element signal during reproduction. Further, a capacitor Cf is connected in parallel with the feedback resistor Rf. The capacitor Cr acts as a low-pass filter, and averages the intermittent pulses during reproduction to create a smooth signal.

Here, returning to FIG. Gain switching circuit 2
The output signals of 65c and 265e are output to a subtraction circuit 264, and the subtraction circuit 264 detects the difference to generate an AT control signal. Also, the gain switching circuits 265d1 to 265d1
265d4 corresponds to the four light receiving element pieces of the four-divided light receiving element 231d, but the gain switching circuits 265d1 and 265d1 corresponding to the light receiving element pieces in the diagonal direction of the light receiving element 231d.
The output signal of 65d3 and the output signals of gain switching circuits 265d2 and 265d4 are added to adders 601 and 60, respectively.
It is added by two. The difference between the output signals of the adders 601 and 602 is detected by the subtractor 603, and the difference is output as an AF control signal.

The output signals of the adders 601 and 602 are added by the adder 604, and the signals are divided into four divided light receiving elements 231d.
Is generated. The sum signal of the four divided light receiving elements is output as an information reproduction signal RF. Adder circuit 60
1, 602, 604 and the subtraction circuit 603 correspond to the addition and subtraction circuit 263 of FIG. The output signals of the gain switching circuits 265b and 265f are output to the selection switch 266, and one of the DV (direct verify) signals according to the moving direction signal from the recording signal generation circuit 262.
The signal is selectively output.

More specifically, if the scanning direction of the light spot is the F direction as shown in FIG.
Reference numeral 6 is connected to the F side, and the signal on the light receiving element 231b side is output to the recording signal creation circuit 262 as a verifying signal. On the other hand, if the scanning direction of the light spot is the L direction, the selection switch 266 is connected to the L side, and the signal on the light receiving element 231f side is used as the verification signal as the recording signal creation circuit 26.
2 is output. That is, since the verifying light spots S2 and S4 are radiated to both sides of the recording light spot S3, if the scanning direction of the light spot changes between the forward path and the return path of the optical card 1, the recording light spot corresponding thereto is changed. After that, the verifying signal reproduced by the light spot to be scanned is selected. The recording signal creation circuit 262 performs verification at the same time as recording using the selected verifying signal.

FIG. 13 is a timing chart of a laser drive signal when verifying is performed simultaneously with recording. FIG.
3 (a) is an output RCL of the reproduced clock generation circuit 704.
K, FIG. 13B shows the recording signal WD, and FIG.
This is the output RCLK2 of the D circuit 805. First, when the recording signal WD is off, that is, during reproduction (reproduction pulse section), the output RCLK2 of the AND circuit 805 is output to the switch 804. At this time, the switch 80 is turned on only during the ON period determined by the predetermined frequency and the duty of the pulse signal RCLK2.
4 is turned on, the output current Ir of the current source 802 is supplied to the semiconductor laser 221, and the semiconductor laser 221 emits intermittently with the power Prmax corresponding to the output current Ir. Next, when the recording signal WD is turned on (recording pulse section), the output RCLK2 of the AND circuit 805 is turned off, so that the switch 804 is turned off, and the output current Ir of the current source 802 is not supplied to the semiconductor laser 221. on the other hand,
At this time, since the switch 803 is turned on, the current source 801 is turned on.
Is supplied to the semiconductor laser 221 and the recording laser power Pw corresponding to the current Iw is applied to the semiconductor laser 221.
Emits light.

The semiconductor laser 221 emits light intermittently at the time of reproduction (reproduction pulse section), so that the maximum power at the time of reproduction is increased. Therefore, the astigmatism of the semiconductor laser at the time of reproduction and the astigmatism at the time of recording are increased. Can be reduced. That is, the change in the size of the light spot between recording and reproduction due to astigmatism is reduced, so that a signal of a constant level can be obtained. The average power at the time of intermittent light emission at the time of reproduction is a power at which reproduction light deterioration does not cause a problem when a certain track on the optical card 1 is scanned a predetermined number of times or less. In the above description, during playback,
It refers to both non-recording (reproduction pulse section) between recording pulses during recording and reproduction at the time of reading information. During the recording period, direct verification is performed using a signal between recording pulses and a signal at the time of the recording pulse.

[0035]

However, in the above-mentioned conventional apparatus, since the recording signal WD and the reproduction clock RCLK are not synchronized, the average value of the light emission power in the reproduction pulse section of the recording signal does not become a constant value. There is a problem that the average level of the detection signal of the photodetector 231 changes, and the S / N of the AT and AF control signals and the verifying signal deteriorates. This problem will be described in detail with reference to FIG. FIG. 14 shows the recording signal WD and the reproduction clock signal RCLK.
4 is a timing chart in which a laser drive signal P and the like during recording / reproduction are enlarged. 14A shows a reproduction clock RCLK signal, and FIG. 14B shows a recording clock signal WCL.
K, (c) is the recording signal WD, (d) is the reproduction clock signal RCLK2, and (e) is the laser drive signal P. Also,
(F) is the output waveform of the gain switching circuit when there is no Cr and Cw capacitors in FIG. 11, and (g) is the actual output waveform of the gain switching circuit.

In the conventional information recording / reproducing apparatus, the reproduction clock of (a) and the recording signal of (c) are not particularly synchronized, so that the number of intermittent pulses in the reproduction pulse section of the recording signal is not constant. That is, A in FIG. 14C has a length of 1T and B has a length of 2T. In the case of the timing of the reproduction clock and the recording signal in FIG. 14, the number of reproduction pulses in the 1T section of A is 4 and 2 in B.
The number of reproduction pulses in the T section is seven. In this case, 1
Assuming that there are n reproduction pulses in the T section, in order to keep the reproduction average power Prv constant, 2n, 3T in the 2T section
3n is required for the section and 4n is required for the 4T section,
If the number of intermittent pulses in the reproduction pulse section differs in this manner, the average level of the output of the gain switching circuit during reproduction does not become constant as shown in FIG. / N becomes worse.

Here, the time of the reproduction pulse section is Tr, the reproduction pulse width is Tp, the power of the reproduction pulse is Prmax,
The average reproduction power Pav when the number of reproduction pulses in the reproduction pulse section is n is obtained as follows: Pav = (Prmax · Tp · n) / Tr (1) Therefore, Tr, Tp, Prm are obtained from the equation (1).
It can be seen that, even if ax is constant, if n is not constant, the reproduction average power Prv will not be constant.
In this case, n indicates that there are n in the 1T section, and in order to keep the reproduction average power Prv constant, it is 2n in the 2T section, 3n in the 3T section, and 4n in the 4T section.

The detection signal level of the photodetector is determined as follows. When the currents flowing through the light receiving elements are PIw and PIrab (which are respectively proportional to the light emission powers) when the light is reflected by a reflection surface having the same reflectance at the time of the light emission powers Pw and Pav, the gain is switched between recording and reproduction. The relationship between the feedback resistances Rw and Rp of the amplifier, the reproduction average current PIrv, and the recording current PIw for equalizing the output voltage of the circuit is as follows.

The output voltage of the gain switching circuit = PIav · Rr = PIw · (Rw // Rr) (2) When the reproduction average power PIrab is not constant, the output voltage of the gain switching circuit is equal between recording and reproduction. (PIrmax in FIG. 14 (f) is the reproduction power Prmax.
Shows the current flowing in the light receiving element at the time of (1).

For example, if the reproduction pulse section of the 1T pit is 4
us, the reproduction pulse width Tp is about 0.2 us, and n becomes about 20. If n is different from one another, a fluctuation of the light emission power of 5% occurs, which is a size that cannot be ignored. Such a change in the output voltage deteriorates the S / N of the signal. Then, when the S / N of the AT and AF control signals deteriorates,
Focusing and tracking control become unstable as an influence on the AF control signal, so that recording and reproduction cannot be performed normally. If the S / N of the verifying signal deteriorates, the waveform of the verifying signal is adversely affected. There was an inconvenience of disappearing.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an optical information recording apparatus capable of performing a stable recording with a constant average level of light emission power in a reproduction pulse section.

Another object of the present invention is to provide an optical information recording apparatus capable of stabilizing the level of a verifying signal and performing highly reliable simultaneous recording.

[0043]

An object of the present invention is to divide a light beam emitted from a light source into a plurality of light beams for recording and servo control, and to drive the light source according to a recording signal. A means for intermittently emitting light in response to an intermittent pulse signal during a reproduction pulse section of the recording signal; a means for relatively moving a recording light beam of the light source and a recording medium to record information on the medium; An optical information recording apparatus comprising: means for detecting reflected light of a control light beam from a medium; and means for generating a servo control signal by switching a gain for amplifying a detected signal according to a recording signal. , The recording signal is synchronized with an intermittent pulse signal in a reproduction pulse section of the recording signal.

It is another object of the present invention to provide a means for dividing a light beam emitted from a light source into a plurality of light beams for recording and verification, driving the light source in accordance with a recording signal, and Means for intermittently emitting light in response to an intermittent pulse signal in a reproduction pulse section; means for relatively moving a recording light beam of the light source and a recording medium to record information on the medium; and a medium for the verifying light beam. Means for detecting reflected light from the device, means for generating a verifying signal by switching the gain for amplifying the detected signal in accordance with the recording signal, and recording by comparing the generated verifying signal with the recording signal. And a means for performing simultaneous verification with the recording signal, wherein the recording signal is synchronized with an intermittent pulse signal in a reproduction pulse section of the recording signal. It is achieved by an optical information recording apparatus characterized.

[0045]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the overall configuration of the optical information recording / reproducing apparatus according to the present embodiment is the same as that shown in FIG. 6, and the optical card shown in FIG. 4 is used as a recording medium. The LD driver 261 uses the circuit shown in FIG. 9, the signal processing circuit uses the circuit shown in FIG. 10, and the gain switching circuit 265 uses the circuits shown in FIGS. However, this embodiment is characterized by the configuration of the recording signal creation circuit 262.

FIG. 1 is a block diagram showing a configuration of a recording signal generation circuit used in the present embodiment. The same parts as those of the conventional circuit of FIG. In FIG. 1, first,
The MPU 701 includes a scanning motor, an AT,
It controls hardware such as the F actuator.
The MPU 701 also receives a pulse signal EN indicating format information from the host computer 703 for dividing one track into a plurality of sectors for recording and position information of an encoder attached to a scanning motor (not shown).
A recording area signal WZ is generated based on C. Further, a recording signal WD corresponding to the information pit string is generated according to the format information and the recording data from the host computer 703, and the recording signal WD is output with reference to the recording area signal WZ so that the recording signal WD can be recorded in a desired sector. . At the time of reproduction, the recording signal WD is off.

The reproduction clock generation circuit 704 generates a reproduction clock signal RCLK, and this RCLK is a clock for causing the semiconductor laser 221 to emit light intermittently at a predetermined frequency and duty during reproduction (reproduction pulse section).
Here, in the present embodiment, the reproduced clock generation circuit 704
Is input to the frequency dividing circuit 101, and the output signal of the frequency dividing circuit 101 is input to the MPU 701 as the recording clock signal WCLK. That is, by dividing the reproduction clock signal RCLK, the recording clock signal W
CLK is created. The recording clock signal WCLK is M
It is used as a reference clock when the PU 701 generates the recording signal WD, and is supplied to a parallel / serial converter in the MPU 701.

Therefore, since the recording clock signal is created by dividing the reproduction clock signal, the reproduction clock signal R
CLK is synchronized with the phase of the recording clock signal which is the reference clock of the recording signal. This is to make the average output of the gain switching circuit constant during reproduction (reproduction pulse section) as described later in detail. Although not shown in FIG. 1, the information reproduction signal is subjected to predetermined signal processing at the time of reproduction to generate reproduction data, and a verifying signal is binarized simultaneously with a circuit for transferring to the host computer 703 and recording. There is provided a circuit which compares this with a recording signal and performs verification at the same time as recording, that is, direct verification.

FIG. 2 is a time chart showing signals of various parts of this embodiment. FIG. 2A shows the reproduced clock signal RC.
LK, FIG. 2B shows the recording clock signal WCLK, and FIG.
(C) is the recording signal WD. 2D shows the reproduced clock signal RCLK2, FIG. 2E shows the laser drive signal P, and FIG. 2F shows the output signal waveforms of the gain switching circuits 265b to 265f when there is no capacitor. 2
(G) is an actual output waveform of the gain switching circuits 265b to 265f. First, the reproduced clock signal R shown in FIG.
CLK is the semiconductor laser 22 during reproduction (reproduction pulse section).
1 is a clock for intermittently emitting light at a predetermined frequency and duty. The frequency of this intermittent light emission is set to a frequency sufficiently higher than the band of the photodetector and the gain switching circuit,
The output of the gain switching circuit is averaged.

Since the recording clock WCLK shown in FIG. 2B is generated by dividing the reproduction clock RCLK by the frequency divider 101, a predetermined number of falling edges of the reproduction clock RCLK are counted and ON / OFF is repeated. ing. This recording clock WCLK is input to a parallel / serial converter built in the MPU 701,
By synchronizing the recording data in byte units transferred from 03 with a recording clock WCLK, a recording signal WD of a serial signal corresponding to a recording pit string is generated. FIG.
(C) is a recording signal WD, which is generated in synchronization with the rising and falling edges of the recording clock WCLK. Therefore, the recording signal WD is synchronized with the reproduction clock signal RCLK. Here, since the recording signal WD is off during reproduction (reproduction pulse section), the switch 803 is turned off, and the output current Iw of the current source 801 is changed to the semiconductor laser 221.
Not supplied to Also, when the recording signal WD is off, the output of the inverter 806 is turned on, so that the AND gate 80
The reproduction clock RCLK2 is output to the output of the counter 5. Then, the switch 804 is turned on only during the on-period determined by the predetermined frequency and the duty of the reproduction clock RCLK2, and the output current Ir of the current source 802 is changed to the semiconductor laser 221.
The semiconductor laser 221 emits light intermittently at the reproduction light power Prmax corresponding to the output current Ir as shown in FIG.

On the other hand, during recording (recording pulse section), the recording signal WD is turned on, so that the switch 803 is turned on.
The output current Iw of the current source 801 is supplied to the semiconductor laser 221. When the recording signal WD is on, the output of the inverter 806 turns off, and the output of the AND gate 805 also turns off. Therefore, the switch 804 is turned off, and the output current Ir of the current source 802 is changed to the semiconductor laser 221.
Not supplied to That is, only the output current Iw of the current source 801 is supplied to the semiconductor laser 221,
1 emits light with the recording light power Pw corresponding to the output current Iw as shown in FIG.

Here, in the information recording area, the recording signal and the intermittent pulse signal in the reproduction pulse section are synchronized as shown in FIG. 2E, and the reproduction light peak power Prmax and the recording light peak power Pw Are consistent.
By synchronizing the recording signal and the intermittent pulse signal in this way, the number of reproduction pulses in the reproduction pulse section becomes 3 at 1T and 6 at 2T as shown in FIG. Is an integral multiple of the number of intermittent pulses at T. Therefore, according to equation (1), the average power Plav during reproduction (reproduction pulse section) is constant.

Therefore, if the feedback resistor is set so that the output voltage of the gain switching circuit becomes equal between recording and reproduction by equation (2), the output waveform of the gain switching circuit when there is no capacitor is shown in FIG. (F), the actual output waveform of the gain switching circuit is as shown in FIG. As is clear from FIG. 2G, the output voltage of the gain switching circuit in the reproduction pulse section is constant, and the quality of the AT and AF control signals and the verifying signal can be improved. Here, the meaning that the output voltage of the gain switching circuit in the reproduction pulse section is constant means that the level becomes the same when the reflected light reflected from the same surface is detected. Therefore, an accurate signal level can be obtained according to the reflectance.

Next, another embodiment of the present invention will be described. 1 and 2, the recording clock WCLK
Is set to coincide with the fall of the reproduction clock RCLK, but in this embodiment, a delay of time Td is provided. FIG. 3 is a time chart showing the operation of the present embodiment. 3A to 3G are FIGS. 2A to 2G, respectively.
It corresponds to. As shown in FIGS. 3A and 3B, the number n of reproduction pulses per 1T in the reproduction pulse section is constant even when there is a delay of time Td between the fall of the reproduction clock RCLK and the rise and fall of the recording clock WCLK. Becomes Accordingly, since the average value of the light emission power during reproduction is constant, the output waveform of the actual gain switching circuit is also the same as that of FIG.
(G), the output voltage of the gain switching circuit in the reproduction pulse section can be kept constant, and the quality of the AT and AF control signals and the verification signal can be improved.

In the above embodiment, the recording clock WCLK is generated by dividing the reproduction clock RCLK by the frequency divider 101. However, the recording is performed by dividing the original clock signal (such as the reference clock of the apparatus). Even if the signal WD and the reproduction clock signal RCLK are created, the reproduction clock signal RCLK and the recording signal WD have a fixed time relationship, and therefore can be synchronized. Although the reproducing light peak power Pr and the recording light peak power Pw are matched, it is not necessary to consider the duty of the intermittent pulse so as to obtain the required reproducing power.

[0056]

As described above, according to the present invention, by synchronizing the recording signal and the intermittent pulse signal in the reproduction pulse section of the recording signal, the average value of the light emission power in the reproduction pulse section can be made constant. The level of the output of the gain switching circuit in the reproduction pulse section can be kept constant. Therefore, since the quality of the servo error signal can be improved, accurate servo control can be performed, and information can be recorded with high accuracy. Further, the quality of the direct verification signal can be improved, and the direct verification can be performed with high accuracy. Further, the output of the clock generator for generating the intermittent pulse signal is divided to generate a recording clock, and this clock and the recording signal are synchronized to synchronize the recording signal and the intermittent pulse signal. One can achieve synchronization, the circuit configuration can be simplified, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of an optical information recording apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the embodiment of FIG. 1;

FIG. 3 is a time chart for explaining an operation of another embodiment of the present invention.

FIG. 4 is a plan view of the optical card.

FIG. 5 is an enlarged view showing a part of the optical card of FIG. 4;

FIG. 6 is a configuration diagram showing a conventional optical card information recording / reproducing apparatus.

FIG. 7 is a sectional view showing a diffraction grating of the apparatus of FIG.

FIG. 8 is a block diagram showing a recording signal generation circuit of the apparatus of FIG.

FIG. 9 is a circuit diagram showing an LD driver of the device of FIG.

FIG. 10 is a circuit diagram showing a signal processing circuit of the device of FIG. 6;

11 is a circuit diagram showing a gain switching circuit of the device shown in FIG.

FIG. 12 is a circuit diagram showing a gain switching circuit for RFR and RFL of the device of FIG. 6;

FIG. 13 is a diagram showing laser drive timing of the apparatus in FIG. 6;

FIG. 14 is a diagram showing the laser drive timing of the apparatus of FIG. 6 in detail.

[Explanation of symbols]

 101 Frequency divider 221 Semiconductor laser 228 Objective lens 231 Photodetector 250 Diffraction grating 261 LD driver 262 Recording signal generation circuit 265 Recording / reproduction gain switching circuit 266 Selection switch 401 Optical card 701 MPU 703 Host computer 704 Reproduction clock generation circuit

Claims (3)

[Claims] 1. A means for splitting a light beam emitted from a light source into a plurality of light beams for recording and servo control, driving the light source in accordance with a recording signal, and intermittently generating a reproduction pulse section of the recording signal. Means for intermittently emitting light in response to a pulse signal, means for recording information on a recording medium by relatively moving a recording light beam of the light source and a recording medium, and light reflected from the medium of the servo control light beam And an optical information recording apparatus comprising means for generating a servo control signal by switching a gain for amplifying the detected signal in accordance with the recording signal, wherein the recording signal and the recording signal An optical information recording device for synchronizing an intermittent pulse signal in a reproduction pulse section. 2. A means for splitting a light beam emitted from a light source into a plurality of light beams for recording and verification, driving the light source according to a recording signal, and intermittent pulses in a reproduction pulse section of the recording signal. Means for intermittently emitting light in accordance with a signal, means for recording information on a recording medium by relatively moving a recording light beam of the light source and a recording medium, and detecting reflected light of the verifying light beam from the medium Means for generating a verifying signal by switching a gain for amplifying the detected signal in accordance with the recording signal;
An optical information recording apparatus comprising means for comparing the generated verifying signal with a recording signal and performing verification at the same time as recording, wherein the recording signal is synchronized with an intermittent pulse signal in a reproduction pulse section of the recording signal. An optical information recording device, characterized in that: 3. A recording clock is generated by dividing an output of a clock generator for generating the intermittent clock signal with a frequency divider, and the recording is performed by synchronizing the generated recording clock signal with the recording signal. 3. The optical information recording apparatus according to claim 1, wherein the signal and the intermittent pulse signal are synchronized.