JPH1139685A - Optical information recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent saturation in an amplifier and to prevent the leakage of a carrier to an adjacent photodetector by bypassing a feedback resistor connected between the input/output of the amplifier amplifying the output signal of the photodetector not using its signal for the period of a reproducing photodetector, or recording power. SOLUTION: A diode D1 bypasses the resistor Rf so that the photocurrent of the photodetector in the recording power at a recording time doesn't flow through the resistor Rf . By using such a diode D1 , a limit due to the diode D1 isn't applied at a reproducing time, and a regenerative signal is amplified by a gain decided with the resistor Rf . Further, the recording power at the recording time is limited by the diode D1 before arriving at a saturated voltage limited by a power source of an operational amplifier 101, and since the resistor Rf is bypassed, the saturation of the operational amplifier 101 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for optically recording or reproducing information on an information recording medium.

[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 information 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 array 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 accesses a desired information track, and the information track is scanned to record or reproduce information.

An optical head is provided with a focusing lens for narrowing a light beam, and an objective lens is used as this lens. As such an objective lens,
The optical head body is held so as to be independently movable in the optical axis direction (focus direction) and the direction (tracking direction) orthogonal to the information track of the recording medium in each direction. Such an objective lens is generally held through an elastic member, and the focus and the movement of the objective lens in the tracking direction are generally driven by an actuator utilizing magnetic interaction.

FIG. 6 shows a schematic plan view of an 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. An information track 402 is provided on the information recording surface of the optical card 401.
Home position 403 as a reference position for access to
Is provided. The information tracks 402 are 402-1 and 402-
2,402-3...

As shown in FIG. 7, a tracking track 504 is adjacent to each information track 402.
-1, 504-2, 504-3... These tracking tracks are used as guides for auto tracking (hereinafter abbreviated as AT) for controlling the light spot so as not to deviate from the information track during light spot scanning during information recording and reproduction.

Such an AT control detects an offset (AT error) of a light spot from an information track and uses the detected information to control a tracking actuator for driving an objective lens in a tracking direction. It is controlled by returning to. That is, the servo control circuit moves the objective lens in the tracking direction (D direction) according to the AT error, thereby controlling the light spot so as not to 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 abbreviated). Such AF control detects a deviation (AF error) of a light spot from a focused state,
The detection signal is controlled by feeding it back to an AF control circuit for controlling a focus actuator for moving the objective lens in the optical axis direction. That is, by moving the objective lens in the focus direction according to the AF error, the control is performed so that the light spot is focused on the optical card surface (recording layer).

Here, in FIG. 7, S1, S2, S
Reference numerals 3, S4, S5, S6, and S7 indicate light spots irradiated on the information tracks of the optical card. AT control is performed using the light spots S1 and S5 of which the tracking tracks 504-2 and 504-3 are partially applied. Further, the light spot S3 is used to perform AF control, create information pits during recording, and read information pits during reproduction. Further, the information pits immediately after recording are verified using the light spots S2 and S4.
The information pit is read out at the time of reproduction using steps 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. 8 is a block diagram showing an optical information recording / reproducing apparatus using an optical card as an information recording medium. FIG.
221 denotes a semiconductor laser as a light source, which emits a laser beam having a wavelength of 830 nm polarized in a direction perpendicular to the track, for example. 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. The light detector 231 is
As shown in FIG. 9, the light receiving elements 231a, 231b, 231
c, 231e, 231f, and 231g, and one quadrant light receiving element 231d divided into four.
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. 261 is a laser driver (hereinafter, LD)
Reference numeral 262 denotes an MPU.

Here, when information is recorded on the optical card 401 by the optical head, in accordance with a recording command from the MPU 262,
A drive current at a recording level is supplied to the semiconductor laser 221 by the LD driver 261. When reproducing information, the LD driver 261 supplies a reproduction level current to the semiconductor laser 22 according to a reproduction command from the MPU 262.
1 is supplied. The semiconductor laser 221 is driven in this manner, and the light beam emitted from the semiconductor laser 221 becomes a divergent light beam and enters the collimator lens 223. After being collimated by the collimator lens 223, the light enters the two-dimensional diffraction grating 250,
, The light beam is divided into seven effective light beams (0th-order diffracted light and 1st-order diffracted light in three directions).

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 into minute light spots by the objective lens 228 and irradiated onto the optical card 401. As shown in FIG. 7, the irradiated light is divided into light spots S1, S2 and S6 (+ 1st-order diffracted light), S3 (0th-order diffracted light), S4,
S5 and S7 (-1st-order diffracted light). Light spot S3
Indicates recording, reproduction and AF control as described above, and S1 and S5 indicate A
T 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. 7, the spot positions on the optical card 401 are such that the light spots S1 and S5 are on adjacent tracking tracks, and the light spots S2, S3 and S4 are information tracks 402- between the tracking tracks.
2, the light spot S6 is on the information track 402-1 adjacent to the information track 402-2, and the light spot S7 is on the information track 402 adjacent to the information track 402-2.
-3. The light spots S2 and S4 for verification are located before and after the light spot S3.

In this manner, the light spot is irradiated onto the optical card 401, 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, and
7 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, is reflected toward the detection optical system by its characteristics, and is separated from the incident light beam from the semiconductor laser 221. The detection optical system is a spherical lens 2
29, a cylindrical lens 230, and a photodetector 231. The 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 used as a light detector 231 composed of a plurality of light receiving elements.
Is detected by Each light receiving signal of the plurality of light receiving elements of the photodetector 231 is sent to the recording / 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. . In other words, MPU
The gain for amplifying the signal is switched in accordance with the recording / reproduction gain switching signal output from the H.262, so that the signal of each light receiving element is maintained at a constant signal level.

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 an MPU 262. In the addition and subtraction circuit 263, as described later in detail, an AF control signal (focus error signal) and an information reproduction signal RF
The subtraction circuit 264 generates an AT control signal (tracking error signal) and sends it to the MPU 262.
The selection switch 266 includes an MPU 262 as described later.
A verifying signal is selected in accordance with a moving direction signal (a signal indicating a scanning direction of a light spot) from the camera. MPU2
At 62, a focus actuator and a tracking actuator (not shown) are driven based on the AF control signal and the AT control signal, and the objective lens 228 is displaced in the focus direction and the tracking direction.
Performs focus control and tracking control.

When reproducing information, the MPU 26
In step 2, information reproduction signals RF and RFR and RFL are each 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 verifying at the same time as recording, that is, direct verifying.

FIG. 10 is a schematic diagram of the diffraction grating 250.
In the drawing, reference numeral 250a denotes an AT diffraction grating forming unit for generating an AT control light beam that becomes the spots S1 and S5;
Is a DV diffraction grating forming unit for generating direct verification light fluxes to be spots S2 and S4, and 250c is an RF for generating information reproduction light fluxes to be spots S6 and S7.
An R and RFL diffraction grating forming unit 301 is an incident light beam. Here, 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 beam. 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 as shown in FIG.

The light power ratio of each light spot is such that a recording spot S3 (0-order diffracted light) is emitted when the recording light is emitted.
Is a recording light power for generating a recording pit, and a light spot S3.
The light power of the other spots is determined so that the recording pit is not generated. 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.

FIG. 11 is a specific circuit configuration diagram of the LD driver 261. In FIG. 11, reference numeral 801 denotes a current source that outputs a driving current corresponding to recording light power, and 802 denotes a current source that outputs a driving current corresponding to reproduction light power.
A switch 803 superimposes a recording light current on a reproduction light current in accordance with a recording signal. Reference numeral 221 denotes a cathode ground semiconductor laser. At the time of reproduction, the recording signal is off, and a current corresponding to the reproduction light power is supplied to the semiconductor laser 221 from the current source 802.

On the other hand, at the time of recording, the recording signal is on, the switch 803 is turned on or off in accordance with the recording signal WD, and the semiconductor laser 221 supplies the reproduction light current with the switch 803 on and off from the current source 801. The recording light current is supplied in a superimposed state. Here, as is apparent from FIG. 11, since the semiconductor laser 221 is driven using only the positive power supply _Vcc , the switch 803 uses a PNP transistor type. In order to further stabilize the optical power for reproduction and recording, a semiconductor laser 22 is generally used.
APC (automatic power control) for monitoring a part of the light output of No. 1 and applying feedback.

FIG. 9 shows a photodetector 231, a recording / reproduction gain switching circuit 265, an addition / subtraction circuit 26 of the apparatus shown in FIG.
3, a signal processing circuit including a subtraction circuit 264 and a selection switch 266. Reference numeral 231 denotes a light detector, which includes light receiving elements 231a, 231b, 231c, 231e, 231f,
231g and a four-divided light receiving element 231d.
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. AT
The reflected light from the control light spots S1 and S5 is
1c, 231e, the reflected light of the light spot S3 for AF control, recording, and reproduction is a four-divided light receiving element 231d, and the reflected light of the light spots S2, S4 for verifying is a light receiving element 231.
b, 231f, light spots S6, S for RFR, RFL
The reflected light of No. 7 is received by the light receiving elements 231a and 231g, respectively.

The light receiving element 231b of the photodetector 231
To 231f are output to a recording / reproduction gain switching circuit 26.
5 are input to the corresponding gain switching circuits 265b to 265f. That is, the output signal of the light receiving element 231b is a gain switching circuit 265b, and the output signal of the light receiving element 231c is
Each of the output signals of the four light receiving element pieces of the gain switching circuit 265c and the four divided light receiving elements 231d is output from the gain switching circuit 265.
These are input to d1 to 265d2, 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. These gain switching circuits 265b to 265f
Represents the gain for amplifying the signal as described above.
The output signal of each of the light receiving elements 231b to 231f is held at a constant signal level by the gain switching operation of each gain switching circuit. 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. Since these two light receiving elements use their signals only during reproduction and are not used during recording, gain switching is not necessary and only the gain corresponding to the reproduction power is obtained.

FIG. 12 shows gain switching circuits 256b to 256b.
The configuration of f is shown. A feedback resistor Rr for determining a gain at the time of reproduction is connected between the-input and the output of the operational amplifier 701, and a series circuit of an analog switch 704 switched by a recording / reproduction gain switching signal and a feedback resistor Rw is connected in parallel with the feedback resistor Rr. As the recording / reproduction gain switching signal, a recording signal WD that is turned on and off in accordance with a pit to be recorded is used. When the recording / reproduction gain switching signal is turned on, the analog switch 704 is turned on and the feedback resistor R
The parallel resistance of r and the feedback resistance 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. Also, the gain at the time of recording, that is, the feedback resistance Rr and the feedback resistance Rw
The parallel resistance is determined by a signal of the light receiving element at the time of recording and the gain at which the operational amplifier output becomes the same output as at the time of reproduction. For example, when the ratio between 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.

FIG. 13 shows the R values of the light receiving elements 231a and 231g.
The configuration of the gain switching circuits 265a and 265g for FR and RFL is shown. A negative input and an output of the operational amplifier 901 are connected to a feedback resistor Rf that determines an appropriate gain so that the output of the operational amplifier is not saturated with a light receiving element signal during reproduction. In this case, the gain switching is unnecessary as described above.

Here, as shown in FIG. 9, the output signals of the gain switching circuits 265c and 265e are output to the subtraction circuit 264, and the subtraction circuit 264 detects the difference to generate an AT control signal. The gain switching circuit 265d1
265d4 correspond to the four light receiving element pieces of the four-divided light receiving element 231d, and the gain switching circuit 265 corresponding to the light receiving element pieces in the diagonal direction of the light receiving element 231d.
output signals of d1 and 265d3 and gain switching circuit 26
The output signals of 5d2 and 265d4 are respectively added to an adder 60
1 and 602 are added. 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 four-divided light receiving element 2
A sum signal of 31d is created. The sum signal of the four divided light receiving elements is output as an information reproduction signal RF.

The output signals of the gain switching circuits 265b and 265f are output to a selection switch 266, and one of the DV (direct verify) signals is selectively output according to the moving direction signal from the MPU 262. More specifically, as shown in FIG. 7, when the scanning direction of the light spot is the F direction, the selection switch 266 is connected to the F side, and the signal on the light receiving element 231b side is used as a verifying signal by the MPU.
262. On the other hand, when the scanning direction of the light spot is L
If the direction is the direction, the selection switch 266 is connected to the L side, and the signal on the light receiving element 231f side is set to MP
Output to U262. That is, the recording light spot S3
Are irradiated with the verifying light spots S2 and S4 on both sides of the optical card. Therefore, when the scanning direction of the light spot changes between the forward path and the backward path of the optical card, the light spot scanned after the recording light spot correspondingly changes. The reproduced verifying signal is selected. The MPU 262 performs verification at the same time as recording using the selected verification signal.

[0028]

By the way, in the conventional apparatus, recording is performed at the recording spot S3, reproduced at the same time as recording is performed at the verifying spots S2 and S4, and recorded and reproduced using the obtained verifying signal. Verification is being performed at the same time. Also, the gain switching circuit switches the gain of the output signals of the verifying light receiving elements 265b to 265f, thereby removing the modulation component due to the modulation of the recording spot from the verifying signal. On the other hand, since the light receiving elements 265a and 265g for reproduction are not used at the time of recording, there is no need to switch the gain.
The output signals a and 265g are amplified by the amplifier circuit shown in FIG. These light receiving elements 265a and 265g are used together with the light receiving element 265d for simultaneously reproducing three tracks.

However, since the light receiving elements of the photodetector 231 are arranged close to each other, carriers leak from the light receiving elements 231a and 231g to the adjacent verifying light receiving elements 231b and 231f during information recording, and the verify operation is performed. There is a problem that the application signal is disturbed by the leak current. More specifically, in the gain switching circuit shown in FIG.
_If the resistance value of the resistor _Rf is reduced so that the operational amplifier 901 is not saturated with the output signal of 31 g, the S / N deteriorates, and _if the resistance value of the resistor _Rf is increased to improve the S / N, In addition, since the light amount of the semiconductor laser increases at the time of recording power, the operational amplifier 901 is saturated, and the input impedance increases. Therefore, the verifying light receiving elements 231b and 23 arranged adjacently
If carriers leak to 1f, the light receiving elements 231a, 231
A part of the output current g flows to the light receiving elements 231b and 231f.

FIG. 14A shows the gain switching signal S _G (recording signal WD), and FIG. 14B shows the light receiving element 23 for verification.
1b and 231f show the output current. FIG. 14 (a)
The low level section corresponds to reproduction power, and the high level section corresponds to recording power. In the section of the recording power, the current increases due to the leakage of the carriers from the light receiving elements 231a and 231g, and the current of the light receiving elements 231b and 231f increases while the light emission amount of the recording power is constant. Therefore, as shown in FIG. 14C, the output signals of the gain switching circuits 265b and 265f for verification do not become constant in the section of the recording power, and an error occurs. As a result, there is a problem that the verify signal is disturbed and the verify cannot be performed accurately. Further, the present invention is not limited to this, and the light receiving element 2
AT control light receiving element 231 next to 31a, 231g
When c and 231e are arranged, there is a problem that the AT control signal is disturbed, and when the light receiving element 231d for AF control is further arranged, the AF control signal is disturbed.

FIG. 15 shows Patent No. 25 as an example of the prior art.
No. 34282 is disclosed. This publication prevents the tracking control signal by the sample servo system from being delayed by the saturation of the amplifier. In FIG. 15, reference numeral 200 denotes a photodetector, 201 denotes an amplifier, 202 denotes a next-stage amplifier, 203 denotes a comparator, 205 denotes a switch, and 206 denotes a current source.

When the output current of the photodetector 200 increases with the switch 205 turned off, the output voltage of the amplifier 201 increases. When the output voltage exceeds the reference voltage _Vref , an on signal is output from the comparator 203 to the switch 205. You. As a result, the switch 205 is turned on, and an excessive current of the photodetector 200 flows to the current source 206, so that it is possible to prevent the saturation of the amplifier 201 at the time of recording power. With such a configuration, the signal at the time of the first data reading after the pit writing is transmitted to the amplifier 201 at the time of the writing.
Can be prevented from being delayed due to saturation. However, such a configuration requires the comparator 203, the reference power supply V _ref , the switch 205, the current source 206, and the like, so that there is a problem that the circuit configuration becomes complicated and the cost increases.

An object of the present invention is to provide an optical information recording / reproducing apparatus capable of preventing a carrier from leaking to an adjacent light receiving element with a simple configuration in view of the above conventional problems.

[0034]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light source, means for dividing a light beam of the light source into a plurality of light beams, and recording one of the divided light beams as a recording spot. Means for irradiating on a medium, means for recording information by modulating the recording spot to reproduction power and recording power according to a recording signal during information recording, and a plurality of means for detecting light passing through the recording medium. An optical information recording / reproducing apparatus having a photodetector comprising a light receiving element, wherein an amplifier for amplifying an output signal of a reproducing light receiving element which is not used at the time of recording, among the plurality of light receiving elements of the photodetector; During the period of the recording power of the signal, the signal is used in parallel with the feedback resistor connected between the input and output of the amplifier that amplifies the output signal of the light receiving element that does not use the signal. It is achieved by an optical information recording and reproducing apparatus characterized in that a means for bypassing the resistor during the recording area.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the overall configuration of the present embodiment is the same as that of FIG. 8, and the optical card of FIG. 6 is used as a recording medium. As shown in FIG. 7, seven light spots S1 to S7 are irradiated on the optical card 1, and when information is recorded, information is recorded on the recording spot S3 and reproduced on the verifying spot S2 or S4. The verification at the same time as the recording is performed using the obtained verification signal. Further, it is assumed that information is reproduced using the light spots S3, S6, and S7. The circuit of FIG. 11 is used as the LD driver 261, and the circuit of FIG. 12 is used as the gain switching circuits 265 b to 265 f in the recording / reproduction gain switching circuit 265 of FIG.
It is assumed that the power modulation component due to the modulation of the recording spot is removed from the T, AF control signal and the verification signal.

However, in the present embodiment, the gain switching circuit 265 in the recording / reproduction gain switching circuit 265 of FIG.
It is assumed that the circuit of FIG. 1 is used as a and 265g. R
Since the gain switching circuits 265a and 265g for FR and RFL are used only during reproduction as described above, gain switching is not performed, and a current-to-voltage converter that converts the photocurrent of the light receiving elements 231a and 231g into a voltage signal and amplifies it. Used as In FIG. 1, reference numeral 101 denotes an operational amplifier, and _Rf denotes a resistor for determining a gain during reproduction. -Of the operational amplifier 101
The terminal is connected to the light receiving element 231a of the photodetector 231 in FIG.
(231 g) of the output current is input. The resistor _Rf is set to an appropriate constant so that the necessary S / N is obtained at the time of reproduction, and the operational amplifier 101 is not saturated with the signal of the recording power at the time of recording.

Further, in FIG. 1, the resistor diode D ₁ and R _f is connected in parallel. The diode D ₁
The light receiving element 231a (231
Resistors so photocurrent does not flow through the resistor R _f in g) R _f
It is provided for bypassing. Here, the input current i _r to the operational amplifier 101 in reproduction power of the semiconductor laser 221 (known), is K times the current i _r of the input current reproduction power at the time of recording power i _w = K · i _r ( Known), the forward voltage of the diode D ₁ is V _f , the resistor R _f
Is R, the saturation voltage (known) limited by the power supply of the operational amplifier 101 is V _p , and the output voltage of the operational amplifier 101 required for reproduction is V _ro , the resistance R of the resistor R _f is R = V _ro / i _r (1)

From this resistance value, the output voltage V _wo of the operational amplifier 101 at the time of recording power is as follows: V _wo = K · V _ro (2) If the recording power output of the operational amplifier 101 is not saturated, the diode D ₁ is not required. However, since the amount of light is small during normal reproduction, the reproduction signal is very weak. At the time of recording, the recording power needs to be about 100 times the reproduction power.
Generally, the output voltage V _wo of the operational amplifier 101 at the time of recording power is higher than the saturation voltage V _p limited by the power supply of the operational amplifier 101. Therefore, the necessary condition of the diode D ₁ is as follows: V _p <K · V _ro (3)

When the diode D ₁ is used, the condition that the limit by the diode D ₁ is not applied at the time of reproduction and the saturation voltage limited by the power supply of the operational amplifier 101 is not reached is as follows: V _ro <V _f <V _p . (4) From the above equations (3) and (4), the diode D ₁
The following condition can be obtained: V _p / K <V _ro <V _f <V _p (5) Here, the first term V _p /
The condition based on K and the second term V _ro is the condition of the diode D ₁ required at the time of recording power, and the condition based on the second, third, and fourth terms is the condition of the diode D ₁ for preventing the limit by the diode D ₁ at the time of reproducing power. Of the forward voltage.

By using such a diode D ₁ , a limit is not imposed by the diode D ₁ during reproduction, and the reproduction signal can be amplified by a gain determined by the resistor _Rf . Also, during recording of the recording power, takes the limit by a diode D ₁ before reaching the saturation voltage is limited by the power supply of the operational amplifier 101, so bypassing the resistor R _f, it is possible to prevent saturation of the operational amplifier 101 .

FIG. 14B shows the light receiving elements 231a and 231.
verifying light receiving elements 231b and 231 adjacent to g
Although the output current of f, and a broken line shows the current waveform in the case of using the diode D _1. Figure 1 shows the high level section
Turning on the first switch 803 causes the semiconductor laser 221 to emit light at the recording power, and the low level section is a section during which the switch 803 is turned off and the semiconductor laser 221 emits light at the reproducing power. In the section of the recording power, takes the limit by the bypass action of the diode D _1, the light receiving element 231a, a portion of the current of 231g for flowing through the diode D _1, is not operational amplifier 101 is saturated. Thereby, the light receiving element 231
a, light receiving element 231 for verification adjacent to 231g
No carrier leakage occurs in b and 231f, and the current of the light receiving elements 231b and 231f for verification becomes flat in the section of the recording power as shown by the broken line in FIG. Therefore, the gain switching circuit 2 for verification
The verifying signals at the outputs of 65b and 265f are also shown in FIG.
A normal verify signal can be obtained without being disturbed as indicated by the broken line in FIG.

FIG. 2 shows the configuration of the gain switching circuits 265a and 265g according to the second embodiment of the present invention. In the present embodiment, connecting the diode D ₁ of the bypass to three series. In the embodiment of FIG. 1, the diode D ₁
When the forward voltage _Vf is set so as to satisfy the expression (5), the output voltage _Vro required during reproduction may be limited by _Vf . In the present embodiment, by connecting the diode D ₁ into a plurality series, it is possible to adjust the value of V _f in accordance with the V _ro.

FIG. 3 shows a third embodiment of the present invention. In Figure 3, the switch 10 in place of the diode D ₁
2 is connected in parallel with the resistor _Rf . Switch 102
Are driven by a recording signal, and are turned on in a section where the recording signal is at a high level (recording power) and turned off in a section of a low level (reproducing power). When using a diode D _1, the requirements of the diodes is a (5), in the case of using the switch 102, when the switch is turned off 102 at reproduction power, the conditions of the forward voltage is not applied the limit due to the diode is eliminated _Therefore , the condition of V _p / K <V _ro <V _p (6) may be satisfied.

The condition according to the first and second terms of the equation (6) is a condition that requires the switch 102 at the time of recording power, and the condition according to the second and third terms is a saturation limited by the power supply of the operational amplifier 101 at the time of reproducing power. This is a condition that does not saturate with voltage. As described above, in this embodiment, since the switch 102 is connected in parallel with the resistor _Rf , in addition to the effects of the first and second embodiments, the output voltage V _ro is limited by the power supply voltage during reproduction. Thus, a reproduced signal having a better S / N can be obtained.
Further, since the switch 102 is driven by the recording signal, it can be used even when the signal at the time of the first data reading after the pit writing is delayed due to the saturation of the amplifier at the time of writing as shown in FIG. It is possible.

FIG. 4 shows a fourth embodiment of the present invention. In the embodiment of FIG. 3, the switch 102 is driven by a recording signal, but in the present embodiment, the switch 102 is driven by a recording / reproduction mode switching signal. FIG.
5A shows a recording / reproduction mode switching signal, and FIG. 5B shows a recording signal. The recording / reproducing mode switching signal has a high level in a recording area (a zone indicating a recording sector), and the switch 102 is driven so as to be turned on during this high level section and turned off during a low level section. In the present embodiment, since the verification is performed simultaneously with the recording, the recording area shown in FIG.
The LD driver 261 is driven by the recording signal of (b) to perform recording on the optical card. Since the switch 102 is turned on in the section of the recording area, the operational amplifier 101
, And leakage of carriers to the light receiving element for verification can be prevented.

In the above embodiment, the light receiving element 23
Verifying light receiving element 23 adjacent to 1a, 231g
1b and 231f are prevented, and the disturbance of the verifying signal is prevented.
When light receiving elements for AF control, AT control, and information reproduction are arranged close to 1a and 231g, disturbance of those signals can be similarly prevented. Also, the present invention
AT / A as well as RFR, RFL gain switching circuit
The F control signal is sampled, and the section of the recording power is A
It can be used even when the T / AF control signal is not used. In this case, the gain switching circuit for AT and AF control is replaced with the gain switching circuit shown in FIG.
By using the circuit of FIG. 4, it is possible to similarly prevent saturation of the amplifier and prevent leakage of carriers to the adjacent light receiving element.

[0047]

As described above, according to the present invention, the light receiving element for reproduction or the amplifier for amplifying the output signal of the light receiving element that does not use the signal is connected between the input and output of the light receiving element during the period of the recording power. Since the feedback resistor is bypassed during the period of the recording power, the saturation of the amplifier can be prevented, and the leakage of the carrier to the adjacent light receiving element can be prevented. In particular, when the light receiving element is arranged close to the verifying light receiving element, disturbance of the verifying signal can be prevented and accurate verification can be performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a recording / reproducing mode switching signal used for driving the switch of the embodiment of FIG. 4;

FIG. 6 is a plan view of the optical card.

FIG. 7 is a diagram showing a light spot applied to the optical card of FIG. 6;

FIG. 8 is a diagram showing a conventional optical information recording / reproducing apparatus.

FIG. 9 is a diagram illustrating a signal processing circuit of the device of FIG. 8;

FIG. 10 shows a diffraction grating of the device of FIG.

FIG. 11 is a circuit diagram of an LD driver of the device of FIG.

FIG. 12 is a circuit diagram of a gain switching circuit of the device of FIG.

FIG. 13 is a circuit diagram of a gain switching circuit for RFR and RFL of the device of FIG. 8;

FIG. 14 is a diagram for explaining carrier leakage of a conventional light receiving element.

FIG. 15 is a circuit diagram showing an example of the related art.

[Explanation of symbols]

Reference Signs List 101 Operational amplifier 102 Switch 221 Semiconductor laser 231 Photodetector 231a to 231g Light receiving element 261 LD driver 262 MPU 265 Recording / reproduction gain switching circuit R _f resistor D ₁ diode

Claims (5)

[Claims] 1. A light source, means for dividing a light beam of the light source into a plurality of light beams, means for irradiating one of the divided light beams as a recording spot on a recording medium, and information recording A means for recording information by modulating the recording spot to a reproducing power and a recording power according to a recording signal, and a photodetector comprising a plurality of light receiving elements for detecting light passing through the recording medium. In the optical information recording / reproducing apparatus, among the plurality of light receiving elements of the photodetector, an amplifier for amplifying an output signal of a reproducing light receiving element not used at the time of recording, or the signal during a recording power period of the recording signal, In parallel with the feedback resistor connected between the input and output of the amplifier for amplifying the output signal of the unused light receiving element, the resistor is connected in the period of the recording power of the recording signal or the period of the recording area. An optical information recording / reproducing apparatus characterized by comprising means for bypassing. 2. An optical information recording / reproducing apparatus according to claim 1, wherein said bypass means is a diode. 3. The optical information recording / reproducing apparatus according to claim 1, wherein said bypass means is a switch element. 4. The device according to claim 3, wherein the switch element is driven so as to be turned on during a recording power period of a recording signal or turned on during a recording area of a recording / reproducing mode switching signal. Optical information recording / reproducing device. 5. A light receiving element that is not used during recording among the plurality of light receiving elements or a light receiving element that does not use the signal during a recording power period is close to a verifying light receiving element for performing verification simultaneously with recording. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording / reproducing apparatus is arranged.