JP2001291261A - Square waveform signal correction device, light emission controller, control system and current supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high-speed optical disk writing device. SOLUTION: The optical disk writing device comprises a main sheet 100, a pickup 200 and a flexible substrate 150 for connecting both. Since the flexible substrate 150 has a poor frequency characteristic, the pickup 200 is internally provided with a write strategy circuit 224, etc., for correcting the frequency characteristic in order to raise the level of the rising part of the signal transmitted in the flexible substrate 150 and to lower the level of the falling part. Arrangement is made to consume the current not consumed in a laser diode 300 by a current source and current consumption circuit 122 in the main sheet 100 in order to suppress the calorific value of the pickup 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a square wave signal correction device, a light emission control device, a control system, and a current supply device suitable for use in a writing device for an optical disk or the like.

[0002]

2. Description of the Related Art An optical disk writing apparatus includes a pickup facing a disk and a main sheet on which a control device for performing various controls on the pickup is mounted. Here, since the position of the pickup moves with the writing operation, the main sheet and the pickup are connected by a flexible substrate. The flexible substrate is formed, for example, by sandwiching a plurality of flat conductor wires between two films, and has a large distribution capacity per unit length. Further, since it is necessary to reliably receive the control signal from the main sheet on the pickup side, a solid driver circuit and a receiver circuit are provided on each side.

[0003] In general, a laser diode is used for writing to an optical disk. A plurality of photodiodes for receiving laser light reflected from the optical disk are provided to read information written on the optical disk, monitor a writing state, and perform servo control of the pickup. In this specification, these photodiodes are referred to as “reproducing photodiodes” as first light receiving elements. In addition to the reproduction photodiode, a photodiode for directly receiving the laser emitted from the laser diode is also provided. In this specification, this is referred to as a “front monitor diode” as the second light receiving element.

<Control of laser power> In an optical disk writing device, in order to keep the light emission amount of a laser diode at an appropriate value, the laser diode drive current is changed according to the light reception amount (output current) of a front monitor diode or a reproduction photodiode. Controlled. Since there are three types of control systems called APC, OPC, and ROPC, each will be described.

(1) APC APC is a control system that compares the output current of the front monitor diode with a target value and increases or decreases the laser diode drive current based on the deviation between the two. (2) OPC In the APC, a “target value” is required in advance.
On an optical disc such as a CD-R, a test area for OPC is prepared in advance. Before actually writing to the optical disk using this test area, the laser diode drive current is changed in the form of a staircase wave near the write level and recorded, and then this area is read again to obtain the optimum photodiode output current. To detect. A system that determines the target value based on the detected output current is called OPC.

(3) ROPC The above-mentioned OPC is performed when an optical disk is inserted. However, after the writing operation is actually started, the light emission characteristics of the laser diode fluctuate due to a change in environmental temperature or the like. Therefore, even during writing, the output current of the reproducing photodiode is sequentially detected at the pit formation timing. A system for correcting the target value based on this detection result is called ROPC.

<Write Strategy Processing> As is well known, a signal written on an optical disk such as a CD-R is EF.
This signal is called an M signal, and has a length of 3T to 11T with respect to a predetermined period T, "1" (a period during which a pit is formed) and "0"
Periods (periods in which no pits are formed) occur alternately. The EFM signal is essentially a perfect square wave, but if this square wave is used for laser power control as it is, the pit length will be incorrect due to differences in recording speed, heat accumulation status, etc., or the pit shape will be distorted. And various problems occur.

Therefore, various waveform deformation processes are performed on this square wave so that a normal pit is formed as a result. This process is called a write strategy process, and a specific example (in the case of a CD-R) is shown in FIG. FIG. 9A shows a recording EFM signal, and in synchronism therewith, a write level pulse shown in FIG. 9C, a start level pulse shown in FIG. 9D, and a read level pulse shown in FIG. You.

Then, the constant current I is generated by these pulses.
When IW, IIE, IIR are switched and superimposed,
The recording waveform shown in FIG. 3B, that is, the laser diode drive current is obtained. Immediately after the rising edge of the recording waveform in FIG. 9B, the level is set to a high level by the rise of the start level pulse. This is to prevent the recorded pits from being distorted like teardrops because heat is not accumulated immediately after rising. Since the heat accumulation effect varies depending on the recording speed, the timing "immediately after the rising of the recording waveform" is a timing near the rising when viewed from the recording EFM signal.

Further, immediately after the falling of the recording waveform, the level of the recording waveform is set to a value lower than the read level by the fall of the read level pulse. This is to prevent the end of the recording pit from shifting backward by cooling the heat accumulation up to that point earlier. Also in this case, since the heat accumulation effect differs depending on the recording speed, the timing "immediately after the falling of the recording waveform" is immediately before or immediately after the falling when viewed from the recording EFM signal, that is, near the falling. It's timing. Alternatively, FIG.
As described above, the timing “immediately after the falling of the recording waveform” is immediately before or immediately after the falling of the write level pulse, that is, the timing near the falling of the write level pulse. In FIG. 11B, IIB is a base level current, which is always added to the recording waveform in the write enable state.

[0011]

There is a high demand for an optical disk writing device to increase the speed, but there is a limit to the increase in speed in the prior art, and the conditions are more severe in DVD-R than in CD-R. . This is because the following various problems occur as the speed is increased.

First, as the speed of the optical disk writing device increases, the frequency component of the recording waveform increases. However, when the length of the transmission line using the flexible substrate becomes longer, the distribution capacity causes deterioration of the frequency characteristics, and a problem arises in that the high frequency component of the recording waveform is attenuated and cannot be used. If the writing speed is increased, the laser diode drive current increases. Depending on the type of laser diode, some recent high-speed writing devices have a laser diode drive current of 300 mA or more. Along with this, the amount of heat generated by the pickup also increases, but when such a large amount of current is transmitted on the flexible substrate, the frequency of the current may be high, and unnecessary radiation from this flexible substrate poses a problem. It will be at the level.

By the way, the operation of continuing writing from the continuation to the optical disk on which tracks have been formed halfway in the past is called "additional writing". In order to perform additional writing, the laser diode is turned on with the read power to trace the track, and when the end of the written track is detected, the laser power is increased to the write power.

However, it takes some time for the write power to stabilize to a normal value. If the writing speed is doubled, for example, the number of revolutions of the disk is also doubled.
As a result, writing becomes unsuccessful and errors are likely to occur during reading. In order to prevent this, it is necessary to reduce the time until the write level is stabilized to about half of the conventional level.

Further, as described above, the driver circuit and the receiver circuit interposed between the control signal sender side and the control signal receiver side also become jitter increasing elements at the time of high-speed operation, and become unstable elements of the system. Become. The present invention has been made in view of the above circumstances, and has as its object to provide a square wave signal correction device, a light emission control device, a control system, and a current supply device that can realize a high-speed optical disk writing device.

[0016]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by having the following constitution. Note that the contents in parentheses are examples. In the configuration according to claim 1, a pickup (200) provided close to the recording medium, and a flexible transmission path (150) connected to the pickup and attenuating a high-frequency component of a signal propagated.
And a main unit (100) connected to the pickup via the transmission path, the correction apparatus being provided in a recording apparatus, wherein a first signal is provided on one end of the transmission path provided on the main sheet. A square wave signal transmitting means (116) for supplying a square wave signal, and a second square wave signal received from the other end of the transmission line provided in the pickup, near a rising edge of the second square wave signal. Waveform modifying means (224) for modifying the waveform of the second square wave signal so as to raise the level at a timing in a first predetermined period and to lower the level at a timing near the fall in a second predetermined period. And characterized in that: According to the second aspect of the present invention, there is provided a pickup provided close to a recording medium, a flexible transmission path connected to the pickup for attenuating a high-frequency component of a signal transmitted, and a transmission path. A light emitting control device (FIG. 1) provided in a recording device having a main sheet connected to the pickup via a light emitting element (300) provided in the pickup, and a light emitting device (300) provided in the pickup. One light receiving element (302a to 302f), a second light receiving element (301) provided in the pickup, and a storage means (231) provided in the pickup and storing a target value of the amount of light received by the second light receiving element. , Provided in the pickup, and in the first operation state (recording mode), the second
The amount of light emitted by the light emitting element is adjusted so that the amount of light received by the light receiving element (301) approaches the target value, and in the second operation state (OPC mode), the amount of light received is obtained based on the amount of light received by the first light receiving element. A control unit (230) for writing the set target value to the storage unit; and an operation state setting unit (120) provided on the main sheet and instructing the control unit via the transmission path to select an operation state to be selected.
And characterized in that: Further, in the configuration according to claim 3, in the light emission control device according to claim 2, the control device receives a light reception amount of the second light receiving element as a digital signal and outputs the light emission amount as a digital signal. An AD converter that converts an output current value of the second light receiving element into a digital signal and supplies the digital signal as the light receiving amount to the control device, and a light emitting amount of the digital signal supplied from the control device. A DA converter that outputs a signal proportional to a current value to be supplied to the light emitting element. Further, in the configuration according to claim 4, a pickup provided close to the recording medium, a flexible transmission line connected to the pickup and attenuating a high frequency component of a signal transmitted, and the transmission line A light emitting control device (FIG. 2) provided in a recording apparatus having a main sheet connected to the pickup via a light emitting element (30).
0), a first light receiving element (302a to 302f) provided in the pickup, a second light receiving element (301) provided in the pickup, and a light receiving amount of the second light receiving element provided in the pickup. A light receiving amount transmitting means (228) for converting the first serial signal into a first serial signal and transmitting the first serial signal to the main sheet via the transmission path; and a light receiving amount transmitting means (228) provided on the main sheet and supplied via the transmission path. A control information generating means (230) for generating control information for controlling the light emission amount of the light emitting element, provided on the main sheet, converting the control information into a second serial signal through the transmission path, Control information transmitting means (118) for transmitting the control information to the pickup. Further, in the configuration according to the fifth aspect, the light emission amount of the light emitting element (the output current of the front monitor diode 301) is used as the detection value, and the control target is controlled according to the deviation between the detection value and the target value. A first feedback loop (21) that outputs a manipulated variable of 1 (gate voltage of FET 18)
0, 212, 18) and a second manipulated variable (current D) for controlling the controlled object according to the deviation between the detected value and the target value.
Constant current IIW, IIE, I for A converter 232
IR, IIB command values) and the first
The second feedback loop (210, 208, 226, 22) having a slower response speed than the feedback loop of
8, 118, 230), and controls the light emission amount of the light emitting element to approach the target value. Furthermore, in the configuration according to claim 6, claim 5
In the control system described above, the first feedback loop includes a differential amplifier that receives the received light amount and the target value as an analog signal and outputs the first manipulated variable as an analog value, The second feedback loop is an AD converter that converts the received light amount into a digital value.
A converter, a memory for storing the target value as a digital value, a control device for outputting the second manipulated variable as a digital value based on the received light amount and the target value of the digital value, And a D / A converter for converting the operation amount into an analog value. Further, in the configuration according to claim 7, a pickup provided close to the recording medium, a flexible transmission line connected to the pickup and attenuating a high-frequency component of a current transmitted, and the transmission line A current supply device (FIG. 4) provided in a recording apparatus having a main sheet connected to the pickup via the main sheet, and supplying a current from the main sheet to a light emitting element in the pickup via a switching unit. And first and second lines (151, 15) provided in the transmission line for attenuating high frequency components of a transmitted current.
2) and a current source (2) provided on the main sheet and supplying a constant current to the pickup via the first line.
5) and a dummy load (3
0), and the current supplied via the first line provided in the pickup is complementarily switched and supplied to the dummy load via the light emitting element (300) or the second line. (FET2 to FET16).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION First embodiment 1.1. Configuration of Embodiment 1.1.1. Next, the configuration of the optical disk writing apparatus according to the first embodiment of the present invention will be described with reference to FIG. The optical disk writing device includes a main sheet 100, a pickup 200, and a flexible substrate 150 that connects the two. In the pickup 200, reference numeral 202 denotes a reproduction light processing circuit, which includes a total of six reproduction photodiodes 302a of a four-divided light receiving portion and two light receiving portions disposed above and below the light receiving portion.
To output the reproduction RF signals based on the output currents of the reproduction photodiodes, and output current values A to F of these reproduction photodiodes to calculate and generate various servo signals on the subsequent stage.
To the main sheet 100 via the flexible substrate 150
And supply it to the servo analog chip 102 therein. In the servo analog chip 102, the reproduced RF signal is shaped into a reproduced EFM signal by forming a waveform, and various control signals such as a tracking error signal, a focusing error signal, and a wobble signal are generated using the output signal of each reproducing photodiode.

A decoder 104 decodes the reproduced EFM signal and outputs the result as a parallel digital signal to the outside. A servo DSP 106 generates a tracking servo signal and a focusing servo signal based on the tracking error signal and the focusing error signal. These signals are supplied to the actuator 170 to control the position of the pickup 200.

Reference numeral 108 denotes a wobble BPF, which extracts a necessary wobble component from a wobble signal. A wobble PLL 110 stabilizes the extracted wobble component.

Reference numeral 116 denotes an encoder which generates a recording EFM signal in synchronization with the basic clock WCLK based on a parallel digital signal input from the outside. 114
Is a synchronous circuit, which outputs a write enable signal WE when a recording EFM signal is output. Reference numeral 120 denotes a microcomputer, a ROM in which a program is recorded.
A RAM used as a work area, and a CP for controlling each unit in the main sheet 100 based on the program
U.

Reference numeral 118 denotes a serial interface.
The pickup 200 is provided via the flexible substrate 150.
Various kinds of control signals are exchanged with the serial interface 228. That is, the serial interfaces 118 and 228 convert the information to be transmitted to the other party into a serial signal that is a balanced differential current signal and transmit the serial signal.

A current source / current consumption circuit 122 supplies a constant current to the pickup 200. This constant current is
The peak value of the laser diode drive current (I in FIG. 3)
(IW + IIE + IIR + IIB) with a margin. The current source / current consumption circuit 122
Is provided with a dummy load, and consumes a current returned from the pickup 200.

Next, a write strategy circuit 224 inside the pickup 200 is based on a reception waveform of a recording EFM signal, and is used as a driving waveform of the laser diode 300 when actually recording the recording EFM signal on a medium. A control pulse (see FIG. 3) for performing various waveform deformations as appropriate is generated. In addition, the laser diode 3
In order to perform the APC, OPC, and ROPC control on 00, it is necessary to sample the output current of the reproduction photodiodes 302a to 302f or the front monitor diode 301 at appropriate timing for each. The write strategy circuit 224 also generates these sampling pulses.

By the way, in the conventional optical disk writing apparatus, the write strategy circuit 224 is provided on the main sheet 100 side, but is provided in the pickup 200 in this embodiment. This is because when the writing speed to the optical disk is increased, the high frequency component of the recording waveform increases, and when this is transmitted through the flexible substrate 150, the signal deteriorates significantly.

In this embodiment, since the laser driver 222 can be disposed immediately after the write strategy circuit 224, the load on the write strategy circuit 224 is reduced, and the deterioration of high frequency components is suppressed. Therefore,
The rise / fall time can be kept almost constant, the fluctuation of the duty ratio can be suppressed, further unnecessary intervening circuits can be reduced, and the jitter can be suppressed. Note that also in the present embodiment, the recording E
Although the FM signal and the basic clock WCLK are transmitted, these frequency components and the slew rate are much lower than those of the write waveform subjected to the write strategy.
The effect is small.

Reference numeral 206 denotes an OPC sample-and-hold circuit. When OPC is performed, the reproduction photodiodes 302a to 302f are synchronized with the corresponding sampling pulses.
Of the output current values (depending on the OPC method) are sampled and held. This output current value is output from the reproduction light processing circuit 202. Reference numeral 204 denotes an ROPC sample and hold circuit which samples an output current value of the reproducing photodiode in synchronization with a corresponding sampling pulse during execution of a writing process.

Reference numeral 210 denotes an I / V conversion circuit which converts an output current of the front monitor diode 301 into a voltage signal (indicating an output current value) proportional to the current. A sample / peak / bottom hold circuit 208 samples and holds the output current value of the front monitor diode 301 in synchronization with a corresponding sampling pulse, and holds the peak value and the bottom value of the output current value.

Reference numeral 226 denotes an AD converter, which converts the output voltage of each of the hold circuits 204, 206, 208 into a digital signal. Reference numeral 230 denotes a laser DSP, which stores these hold values in the memory 231 as needed, and emits light of the laser diode (the front monitor diode 301) corresponding to each level of the recording waveform in FIG.
Of the constant currents IIW, IIE, and IIR based on the calculated target values.

Reference numeral 232 denotes a current DA converter, which shunts the constant current supplied from the current source / current consumption circuit 122 based on a command value of the laser DSP 230, and
W, IIE, IIR, and IIB are output. Reference numeral 222 denotes a laser driver, which switches and superimposes these constant currents with each control pulse supplied from the write strategy circuit 224, and outputs the result as a laser diode drive current. Reference numeral 234 denotes a noise superimposing circuit that adds noise to the driving current.

1.1.2. Configuration of Laser Driver 222 Here, the detailed configuration of the laser driver 222 will be described with reference to FIG. In the figure, reference numerals 2 to 16 denote FETs, two pairs corresponding to the constant currents IIW, IIE, IIR, and IIB. The drain end of each pair of FETs is connected to the corresponding constant current source. I have.

Of each pair of FETs, the FE
A base level pulse, a start level pulse, a read level pulse, and a write level pulse are supplied to the gate ends of T2, 6, 10, and 14 in positive logic, respectively. Also,
These control pulses are supplied to the right FETs 4, 8, 12, and 16 in negative logic, respectively.

Accordingly, the on / off state of each pair of FETs is switched complementarily. The output currents of the FETs 2, 6, 10, and 14 driven by positive logic are superimposed, and the result is the drive current ILD for the laser diode 300.
Is output as On the other hand, FET driven by negative logic
Output currents of 4, 8, 12, and 16 are also superimposed.

This current is supplied via the flexible substrate 150 to the dummy load 30 in the current source / current consuming circuit 122.
Supplied to The dummy load 30 has the same impedance as the laser diode 300. In addition,
FET1 provided inside laser driver 222
Reference numeral 8 is used when performing APC in analog, but is not particularly used in the present embodiment.

In this embodiment, the constant currents IIW, IW
Since the switching process of the IE, IIR, and IIB is performed inside the pickup 200, it is not necessary to transmit a large-current laser diode drive current ILD including many high-frequency components via the flexible substrate 150. Therefore, the current value of the drive current ILD can be changed quickly. The current supplied to the dummy load 30 has no inconvenience even if the high-frequency component is attenuated in the flexible substrate 150.

Further, regardless of the switching of the current value of the drive current ILD, each of the constant currents IIW, IIE, IIR, IIB
Are constant. As a result, ringing caused by rapid on / off of current can be prevented, and since the current DA converter 232 operates stably, it can be seen that it is more effective for high-speed writing on an optical disk.

1.2. Next, the operation of this embodiment will be described. First, when a user or the like instructs writing of an optical disk, the operation mode is first set to the OPC mode. That is, a test write command is supplied from the microcomputer 120 via the serial interface 118 so as to write a predetermined test pattern in the test area of the optical disk while changing the recording current, waveform, and the like of the laser diode 300 stepwise. You. At this time, the actuator 170 is controlled via the servo DSP 106 so that the pickup 200 faces the test area.

Next, the test pattern recorded in the test area of the optical disk is read out by the reproduction light processing circuit 202, and the result is supplied to the main sheet 100 as a reproduction EFM signal. The microcomputer 120 compares the contents of the test write instruction with the reproduced EFM signal, and determines the most appropriate recording current waveform from the result. This is the target value in APC.

When the OPC is completed, the target value in the APC is written into the memory 231 based on the result. Thereafter, in the microcomputer 120, the operation mode is switched to the normal recording mode. That is, an EFM signal for recording is generated in the encoder 116 based on a digital signal supplied from the outside, and is supplied to the pickup 200 via the encoder 116. At this time, the write enable signal WE is set to the ON state (write enabled).

In the normal recording mode, APC is controlled. This is performed by sampling the output current of the front monitor diode when the recording EFM signal is "1". Also, as shown in FIG.
During the period in which the recording EFM signal is "0", the recording waveform is set to the read level. In this period, the tracks previously written by the reproducing photodiodes 302a to 302d are read, and based on the result, the actuator is read. The servo signal of 170 is sampled and the actuator control is executed.

2. Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.
In the figure, parts corresponding to the respective parts in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, laser D
SP230, memory 231 and current DA converter 2
Reference numeral 32 is provided not on the pickup side but on the main sheet 100 side.

For this reason, each of the hold circuits 204 and 20
6, 208 are converted to serial signals by a serial interface 228,
0, laser DS via serial interface 118
It will be supplied to P230. Further, the four systems of constant current II generated by the current DA converter 232
W, IIE, IIR, IIB are flexible substrates 15
0 to the laser driver 222.

As described above, in this embodiment, since the laser DSP 230, the memory 231 and the current DA converter 232 are mounted on the main sheet 100 side, the amount of heat generated in the pickup 200 can be further reduced.

Further, the target value in the APC is not only used for controlling the current DA converter 232 in the main sheet 100, but also supplied to the pickup 200 via the serial interface 118. 212 is an analog APC circuit in the pickup 200;
A DA converter for converting the target value to a voltage level;
It comprises a differential amplifier that outputs a voltage proportional to the difference between the light emission amount (output voltage of the I / V conversion circuit 210), which is a voltage level, and a target value.

The output voltage of the differential amplifier is applied to the gate terminal of the FET 18 in the laser driver 222. Thus, if the light emission amount is too strong, the value of the current bypassed via the FET 18 increases, and the laser diode drive current ILD is automatically controlled so as to approach the target value. Therefore, in this embodiment,

(1) Laser DSP 230 via AD converter 226 and serial interfaces 228 and 118
To the constant currents IIW, IIE, II
Digital AP that controls R and IIB
C, and (2) transmitting a target value from the laser DSP 230 to the APC circuit 212 via the serial interfaces 118 and 228, and controlling a current value bypassed via the FET 18 based on a difference between the target value and the detected light amount value. That is, the analog APCs having the contents to be performed are provided in parallel.

The significance of providing two APC loops in parallel will be described. First, the digital APC of this embodiment stores the constant current II in the memory 231.
Initial values of W, IIE, IIR, IIB can be stored. This initial value is the value of each constant current at the time when the previous write operation was completed.

When performing additional writing or the like, environmental conditions such as the ambient temperature at the end of the previous writing and the current time are often different. For this reason, these initial values are not necessarily optimal values, but are values close to the optimal values to some extent.
On the other hand, analog APC must start automatic control from a state where there is no information on the initial value. Therefore, the digital APC is more advantageous than the analog APC in that a value close to an optimum value to some extent can be set as the initial value.

However, the digital AP in the present embodiment
Since C converts a parallel signal into a serial signal and transmits information via the flexible substrate 150, its response speed becomes slow, and it becomes difficult for digital APC alone to cope with high-speed writing. Therefore, in this embodiment, by providing both APC loops in parallel,
It realizes a control system that has both advantages of "can set a reasonable initial value to some extent and can respond at high speed".

3. Modifications The present invention is not limited to the embodiments described above,
Various modifications are possible. For example, in the above-described embodiment, an example has been described in which the present invention is applied to an optical disk writing device. However, the present invention may be applied to a recording medium other than an optical disk and various other electronic devices.

[0050]

As described above, according to the present invention, a high-speed writing process can be performed on an optical disk or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disk writing device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an optical disk writing device according to a second embodiment of the present invention.

FIG. 3 is a waveform diagram of a write strategy process in the first and second embodiments of the related art.

FIG. 4 is a detailed block diagram of a laser driver 222 and the like.

[Explanation of symbols]

2-18 ... FET, 30 ... Dummy load, 100 ...
Main sheet, 102 ... Servo analog chip, 10
4 Decoder, 106 Servo DSP, 108
Wobble BPF, 110 ... Wobble PLL, 116 ...
... Encoder, 118, 228 Serial interface, 120 Microcomputer, 122 Current source / current consumption circuit, 150 Flexible board, 1
70: Actuator, 200: Pickup, 2
02: reproduction light processing circuit, 204: ROPC sample and hold circuit, 206: OPC sample and hold circuit, 208: sample / peak / bottom hold circuit, 210: I / V conversion circuit, 212: APC circuit, 2 to 16: FET, 222: Laser driver,
224: write strategy circuit, 226: AD converter, 230: laser DSP, 231: memory,
232: current DA converter, 234: noise superimposing circuit, 300: laser diode, 301: front monitor diode, 302a to 302f: reproduction photodiode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Noro 10-1, Nakazawa-cho, Hamamatsu-shi, Shizuoka Yamaha Corporation (72) Inventor Nobuaki Tsuji 10-1, Nakazawa-cho, Hamamatsu-shi, Shizuoka Yamaha Corporation F Terms (reference) 5D090 AA01 BB04 CC01 CC16 DD03 DD05 EE02 KK04 LL09 5D119 AA23 BA01 BB03 DA01 EC09 FA33 HA12 HA19 HA45 HA68

Claims (7)

[Claims] 1. A pickup provided near a recording medium, a flexible transmission path connected to the pickup for attenuating a high-frequency component of a signal transmitted, and a pickup connected to the pickup via the transmission path. A square wave signal correcting device provided in a recording device having a main sheet having a first square wave signal provided on the main sheet and supplying a first square wave signal to one end of the transmission path; From the other end of the transmission line
And raising the level in a first predetermined period at a timing near the rise of the second square wave signal,
And a waveform deforming means for deforming the waveform of the second square wave signal so as to lower the level during a second predetermined period at a timing near the falling edge. 2. A pickup provided close to a recording medium, a flexible transmission path connected to the pickup for attenuating a high-frequency component of a signal transmitted, and a pickup connected to the pickup via the transmission path. A light emitting control device provided in a recording apparatus having a main sheet having a light receiving element, a light emitting element provided in the pickup, a first light receiving element provided in the pickup, and a second light receiving element provided in the pickup And storage means provided in the pickup for storing a target value of the amount of light received by the second light receiving element; and provided in the pickup, wherein the amount of light received by the second light receiving element in the first operating state is the target value. And the amount of light emitted from the light emitting element is adjusted to approach A control device that writes the obtained target value to the storage unit; and an operation state setting unit that is provided on the main sheet and instructs the control device to select an operation state to be selected via the transmission path. Characteristic light emission control device. 3. The control device receives the amount of light received by the second light receiving element as a digital signal and outputs the amount of light emission as a digital signal, and converts the output current value of the second light receiving element into a digital signal. An AD converter that converts and supplies the amount of received light to the control device, and a DA converter that outputs a signal proportional to a current value to be supplied to the light emitting element based on the amount of light emission of the digital signal supplied from the control device The light emission control device according to claim 2, comprising: 4. A pickup provided close to a recording medium, a flexible transmission path connected to the pickup for attenuating high frequency components of a signal transmitted, and a pickup connected to the pickup via the transmission path. A light emitting control device provided in a recording apparatus having a main sheet having a light receiving element, a light emitting element provided in the pickup, a first light receiving element provided in the pickup, and a second light receiving element provided in the pickup And a light receiving amount transmitting means provided in the main sheet, the light receiving amount transmitting means being provided in the pickup, converting a light receiving amount of the second light receiving element into a first serial signal, and transmitting the first serial signal to the main sheet via the transmission path. Control information generating means for generating control information for controlling the light emission amount of the light emitting element based on the light reception amount supplied via the transmission path; A light emission control device provided on an in-seat, and having control information transmitting means for converting the control information into a second serial signal and transmitting the second serial signal to the pickup via the transmission path. 5. A first feedback loop for outputting a first manipulated variable for controlling a control target according to a deviation between the detected value and a target value, wherein the detected value is a detected value. And a second feedback loop that outputs a second manipulated variable for controlling the controlled object in accordance with a deviation between the control value and the target value, and has a response speed slower than the first feedback loop. A control system for controlling the light emission amount of the element so as to approach the target value. 6. The first feedback loop comprises:
A differential amplifier that receives the received light amount and the target value as an analog signal and outputs the first manipulated variable as an analog value, wherein the second feedback loop converts the received light amount into a digital value An AD converter for converting, a memory for storing the target value as a digital value, a control device for outputting the second manipulated variable as a digital value based on a light receiving amount and a target value of the digital value, 6. The control system according to claim 5, further comprising a DA converter for converting the second operation amount into an analog value. 7. A pickup provided close to a recording medium, a flexible transmission path connected to the pickup for attenuating a high-frequency component of a current transmitted, and a pickup connected to the pickup via the transmission path. A current supply device provided in a recording apparatus having a main sheet and a current supplied from the main sheet to a light emitting element in the pickup via a switching unit, wherein the current supplied in the transmission path is transmitted. First and second lines for attenuating the high-frequency component of the current, a current source provided on the main sheet and supplying a constant current to the pickup via the first line, and a dummy load provided on the main sheet And supplying the current supplied to the pickup via the first line to the dummy load via the light emitting element or the second line. Current supply device, characterized in that it comprises a switching means for supplying switched complementarily.