JP2003303414A - Head device and information recording/reproducing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head device, by which the necessary information at the information recording/reproducing operation with respect to media can be transmitted to a processing circuit of the outside of the device at a high speed with low distortion, and also an information recording/reproducing device using this device. <P>SOLUTION: A pickup 1 is provided with a 1st light receiving circuit 11 for detecting a light reflected from the media (not shown in figure) to obtain an analog signal and an analog digital conversion circuit 15 for converting the above analog signal into a digital signal, and the device is constituted so that the digital signal is sent out to the 1st processing circuit 21 of a main substrate 2 through a cable 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head device for recording and / or reproducing information on a medium, and an information recording / reproducing device using the head device.

[0002]

2. Description of the Related Art As a conventional information recording / reproducing apparatus, an optical disk apparatus will be described here as an example. A conventional optical disc apparatus has a pickup which is an information recording / reproducing device for an optical disc, and a main substrate on which a processing circuit for controlling the pickup and various signal processing is formed, and a pickup which is a movable portion and a fixed portion. The main board is a flexible cable that can be expanded and contracted. The pickup is configured to send the analog signal obtained by the light receiving circuit or the like as it is to the main board via the flexible cable. The main board digitally converts the analog signal from the pickup and then inputs the analog signal to the processing circuit. It was a composition.

[0003]

Certainly, in the case of the optical disk device having the above-mentioned structure, the reproduction processing of the reproduction signal on the main substrate, the tracking / focusing servo control, or the laser light is performed based on the analog signal obtained by the pickup. It is possible to control the strength of the.

However, as described above, the optical disk device having the above-described structure has a structure in which the pickup and the main board are connected by a flexible cable and an analog signal is transmitted through the flexible cable. As the signal interval becomes shorter with the increase in speed, the influence of delay and distortion of the analog signal caused by the wiring capacitance and reactance component of the flexible cable becomes large, and there is a problem that various processes on the main board cannot be performed accurately. It was In particular, this problem cannot be ignored regarding the analog signal (main reproduction signal) obtained by detecting the reflected light from the optical disk with the recent increase in the capacity and density of the optical disk or the increase in the recording / reproduction speed. It was.

Here, the influence of the wiring capacitance and reactance component of the flexible cable on the output signal of the pickup will be described by taking the settling characteristic showing the response performance to an optical signal as an example. The settling characteristic is the output voltage of the light receiving circuit that detects the reflected light from the optical disc when the laser beam is turned off when information is recorded on the optical disc by turning on / off the high intensity laser beam within a predetermined error range. It is the time to settle within and is determined by the slew rate and ringing characteristics.

Since the slew rate is inversely proportional to the load capacitance attached to the output side of the light receiving circuit, a signal transmission path connecting the pickup and the main substrate is formed by a flexible cable, as in the optical disk device having the above structure. In that case, the wiring capacitance has been one factor that slows the slew rate and deteriorates the settling characteristics. Further, since the ringing characteristic is determined by the load capacitance, reactance component and output stage current associated with the output side of the light receiving circuit, the reactance component of the flexible cable cannot be ignored in the optical disk device having the above configuration.

FIG. 5 is a diagram for explaining the deterioration of the settling characteristic due to the flexible cable. In this figure, the vertical axis represents the laser light amount and output voltage (broken line X; output voltage of light receiving circuit forming pickup, solid line Y; output voltage of pickup measured via flexible cable). The axis shows time.

As shown in the figure, in the optical disk device having the above structure, the settling characteristic is deteriorated by the flexible cable. Therefore, immediately after writing information on the optical disk with the high-intensity laser light, the laser with the lower intensity is used. When reading the address information engraved on the optical disk with light, the analog signal input from the pickup to the main board had distortion that cannot be ignored. Therefore, it is difficult to accurately recognize the address information even if such an analog signal is digitally converted and arithmetic processing is performed, which has been an obstacle in increasing the recording speed. .

Further, in the optical disk device having the above structure, the flexible cable is provided with not only a signal transmission path for transmitting an analog signal, but also a power supply path for supplying a drive current to the laser diode of the pickup. Therefore, there is also a problem in that the analog signal is distorted by external noise caused by the fluctuation of the drive current, and various processes on the main board cannot be performed accurately.

In particular, with the recent increase in the recording speed for optical discs, the laser diode of the pickup is required to have high responsiveness and high output, and the external noise is further generated in the signal transmitted through the flexible cable. Since it is expected that they will be easily overlapped, this problem cannot be ignored for further speedup in the future.

Further, with the recent increase in capacity and density of optical discs, laser diodes of shorter wavelength than before (for example, blue-violet laser diodes [wavelength: 400 n
m]) is used, but generally, when the laser light has a short wavelength, the light receiving sensitivity of the pickup tends to decrease. If the output of the laser diode is higher than that of the conventional one and the same photocurrent as that of the conventional one is obtained by the pickup, the reduction of the signal component can be avoided, but it is transmitted from the pickup to the main board as the drive current of the laser diode increases Since the noise component of the analog signal increases, as a result, the SN ratio may be deteriorated.
On the other hand, when the laser diode is made to have the same output as the conventional one, an increase in noise component can be avoided, but the signal component obtained by the pickup decreases, which may also lead to a deterioration in the SN ratio.

Since the wiring capacitance and reactance component of the flexible cable increase as the wiring length increases, it is effective to reduce the wiring length of the flexible cable as much as possible in order to solve the above problems. However, in order to record / reproduce information on / from the optical disc, the pickup must be moved from the inner diameter to the outer diameter of the optical disc. Therefore, the wiring length of the flexible cable must be at least as long as the radius of the optical disc. there were. Therefore, there is a limit to solving the above problem by shortening the wiring length.

Further, as a conventional technique for solving the above-mentioned problems, Japanese Patent Laid-Open No. 2001-266497 proposes a signal processing between a pickup and a main board so that a signal transmitted through a flexible cable can be transmitted. There has been proposed a transmission device that suppresses the frequency and tries to achieve a high information recording speed.

Certainly, with the transmission device having the above-mentioned configuration, it is possible to suppress the frequency of the transmission signal via the flexible cable and increase the information recording speed. However, the transmission device configured as described above needs to complicate signal processing unnecessarily, and since it is not a fundamental solution to signal distortion, if further speedup is aimed at in the future, signal processing becomes more complicated. However, it could be difficult to control.

In view of the above problems, the present invention provides a head device capable of transmitting information necessary for recording / reproducing information to / from a medium to a processing circuit outside the device at high speed and low distortion, and information using the head device. An object is to provide a recording / reproducing device.

[0016]

In order to achieve the above object, a head device according to the present invention detects information necessary for recording and / or reproducing information on a medium and outputs an analog signal. The obtained sensing circuit and an analog / digital conversion circuit for converting the analog signal into a digital signal are provided, and the digital signal is sent to a processing circuit outside the apparatus.

More specifically, in the head device according to the present invention, in the head device having the above-mentioned structure, the head device has a light emitting circuit for irradiating the medium with laser light, and the sensing circuit serves as a reflection from the medium. A first light receiving circuit for detecting light to obtain an analog signal, a second light receiving circuit for detecting intensity of the laser light to obtain an analog signal, and a temperature sensor for detecting ambient temperature of the light emitting circuit to obtain an analog signal Of these, at least one of them is provided.

The head device having the above structure has a drive circuit for driving the light emitting circuit and a control circuit for controlling the drive circuit based on the analog signal and / or the digital signal. It may be configured.

Further, in the head device having the above structure, it is preferable that the sensing circuit and the analog-digital conversion circuit are formed in one chip or one package.

In the head device having the above structure, it is preferable that each ground terminal of the sensing circuit and the analog-digital conversion circuit is connected to a common ground wiring.

Further, the information recording / reproducing apparatus according to the present invention,
The head device having the above configuration, the main substrate on which the processing circuit is formed, and the cable serving as a signal transmission path and a power supply path between the two are provided.

In the information recording / reproducing apparatus having the above structure, the signal transmission path of the cable and the power supply path may be arranged and / or electromagnetically separated.

[0023]

1 is a perspective view showing a schematic configuration of an optical disk device according to the present invention. The optical disk device shown in the figure has a pickup 1 which is an information recording / reproducing means for an optical disk (not shown), and a main substrate 2 on which a processing circuit for controlling the pickup 1 and various signal processing is formed. The movable portion of the pickup 1 and the fixed portion of the main substrate 2 are connected by a stretchable cable 3. In addition, the FPC [Flexible Print
ed Circuit] or FFC [Flexible Flat Cable] may be used.

First, the first embodiment of the optical disk device according to the present invention.
An embodiment will be described. FIG. 2 is a block diagram showing the first embodiment of the optical disk device according to the present invention. As shown in the figure, the pickup 1 that constitutes the optical disc apparatus of the present embodiment has a laser diode 11 (hereinafter referred to as LD 11) that irradiates the optical disc with laser light, and records and / or records information on the optical disc. Alternatively, a first light receiving circuit 12 for detecting reflected light from the optical disk to obtain an analog signal as a sensing circuit for detecting information necessary for reproduction, and a first light receiving circuit 12 for detecting an intensity of the laser light to obtain an analog signal. 2 light receiving circuit 13 and LD 11
Temperature sensor 1 that detects the ambient temperature of the vehicle and obtains an analog signal
4 and.

The above first and second light receiving circuits 12 and 13 are
It is composed of a photodiode which is a photoelectric conversion element and an amplifier circuit which amplifies the output voltage thereof. The second light receiving circuit 12 may be a front sensing type formed near the irradiation direction of the LD 11 so that the intensity of the laser light can be detected with high accuracy. In addition, the temperature sensor 14
Is preferably a circuit using the temperature dependence of resistance or the temperature dependence of base-emitter voltage of a bipolar transistor, or a circuit using a thermistor or Peltier element, and is preferably formed near the LD 11.

Furthermore, the pickup 1 of this embodiment is
As a characteristic part thereof, a first analog-digital conversion circuit 15 (hereinafter referred to as a first ADC 15) that converts an analog signal obtained by the first light receiving circuit 12 into a digital signal.
And transmitting the digital signal to the main board 2 via the cable main 3.

On the other hand, the main substrate 2 constituting the optical disk device of this embodiment is the first ADC 15 of the pickup 1.
A first processing circuit 21 that performs decoding processing of a reproduction signal, tracking / focusing servo control, and the like based on the digital signal obtained in step 1, and a motor driver that controls the drive of the servomotor 4 according to an instruction from the first processing circuit 21. 22
And an actuator driver 23 that similarly controls the drive of the actuator 5 in accordance with an instruction from the first processing circuit 21.
And a write signal generation circuit 24 for generating a write signal for the optical disc and an OPC [Optical Power Control] / for generating a laser light control signal based on the analog signal obtained by the first light receiving circuit 12 of the pickup 1. APC [Automatic
Power Control] circuit 26, and second analog-digital conversion circuit 27 (hereinafter referred to as second ADC 27) that converts the analog signals obtained by second light receiving circuit 13 and temperature sensor 14 of pickup 1 into digital signals, respectively.
And a second processing circuit 28 that generates a laser light control signal based on the digital signal obtained by the second ADC 27, and a drive current is supplied to the LD 11 of the pickup 1 based on the write signal and the laser light control signal. Laser diode drive circuit 29 (hereinafter referred to as LD driver 29)
And. The servomotor 4 and the actuator 5 are means for driving the focusing optical system (collimator lens, objective lens, etc.) of the pickup 1 to perform tracking / focusing servo control.

As described above, in the pickup 1 of this embodiment, the analog signal obtained by the first light receiving circuit 12 is converted into a digital signal by the first ADC 15, and the digital signal is sent to the main substrate 2 via the cable 3. It is a configuration for sending.

As described above, by digitizing the transmission signal to the first processing circuit 21 of the main substrate 2 before passing through the cable 3, it is possible to increase the capacity or density of the optical disc, or to improve the recording / reproducing speed. In the case where external noise is likely to be superposed on the cable 3 due to the increase in speed (for example, when a laser diode having a shorter wavelength than that of the LD 11 is used as the LD 11 in order to obtain a photocurrent equivalent to that in the conventional LD 11, Even when the output is higher or when the drive current of the LD 11 is changed at high speed with the increase in recording speed), delay or distortion is less likely to occur in the transmission signal. Therefore, the first processing circuit 21 of the main board 2 can accurately perform the decoding processing of the reproduced signal, the tracking / focusing servo control, and the like.

Further, in the pickup 1 of this embodiment, the analog signal obtained by the first light receiving circuit 12 is input to the first ADC 15 without passing through the cable 3, so that the first ADC 15 deteriorates the settling characteristic due to the cable 3. Of the first processing circuit 2 of the main board 2 based on a waveform close to ideal (see the broken line X in FIG. 5) that is not affected by
It is possible to send a digital signal with less delay and distortion. Therefore, in the optical disk device of the present embodiment, immediately after writing information on the optical disk with high intensity laser light, the operation of reading address information engraved on the optical disk with lower intensity laser light is accelerated. Even in this case, the address information can be accurately recognized.

In the pickup 1 having the above structure, the first light receiving circuit 12 and the first ADC 15 may be formed in one chip or one package. With such a configuration, it is possible to shorten the wiring distance between the two and significantly reduce signal delay and distortion due to wiring capacitance, external noise, and the like. It can also contribute to downsizing of the pickup 1.

In the pickup 1 having the above structure, the ground terminals of the first light receiving circuit 12 and the first ADC 15 may be connected to a common ground wiring. With such a configuration, the stray component signal can be reduced, so that stable detection waveforms can be reproduced.

Next, the second optical disk device according to the present invention
An embodiment will be described. FIG. 3 is a block diagram showing a second embodiment of the optical disk device according to the present invention. As shown in the figure, the pickup 1 which constitutes the optical disk device of the present embodiment converts an analog signal obtained by the second light receiving circuit 13 and the temperature sensor 14 into a digital signal in place of the first ADC 15 described above. The second analog-digital conversion circuit 17 (hereinafter referred to as the second ADC 17) is provided, and the digital signal is sent to the main board 2 via the cable main 3.

With the above-described configuration of the pickup 1, the main substrate 2 constituting the optical disk device of this embodiment converts the analog signal obtained by the first light receiving circuit 12 of the pickup 1 into a digital signal. First analog-digital conversion circuit 25 (hereinafter referred to as the first ADC 25
The second ADC 27 is removed, while the second ADC 27 is removed.

As described above, by digitizing the transmission signal to the second processing circuit 28 of the main board 2 before passing through the cable 3, the capacity and density of the optical disk can be increased or the recording / reproducing speed can be increased. As a result, even if external noise is likely to be superposed on the cable 3, delay and distortion are less likely to occur in the transmission signal. Therefore, the second processing circuit 28 of the main substrate 2 can accurately control the intensity of the laser light.

In the pickup 1 having the above structure, the second light receiving circuit 13, the temperature sensor 14 and the second A
The DC 17 may be formed in one chip or one package. With such a configuration, it is possible to shorten the wiring distance between the two and significantly reduce signal delay and distortion due to wiring capacitance, external noise, and the like. It can also contribute to downsizing of the pickup 1.

Further, in the pickup 1 having the above structure, the second light receiving circuit 13, the temperature sensor 14 and the second A
The ground terminal of DC17 may be connected to a common ground wire. With such a configuration, the stray component signal can be reduced, so that stable detection waveforms can be reproduced.

Next, the third embodiment of the optical disk device according to the present invention.
An embodiment will be described. FIG. 4 is a block diagram showing a third embodiment of the optical disk device according to the present invention. As shown in the figure, the pickup 1 which constitutes the optical disk device of the present embodiment has the first and second ADCs 15 and 17 described above.
In addition to the above, an OPC / APC circuit 16 for generating a laser light control signal based on the analog signal obtained by the first light receiving circuit 12 and a laser light control signal for generating a laser light control signal based on the digital signal obtained by the second ADC 17 are provided. 2 processing circuit 18
And a laser diode drive circuit 19 (hereinafter referred to as an LD driver 19) that supplies a drive current to the LD 11 based on the write signal and the laser light control signal.

With the pickup 1 having the above-mentioned structure, the main substrate 2 constituting the optical disk device of the present embodiment has the first ADC 25 and the OPC / APC circuit 2.
6, the second ADC 27, the second processing circuit 28, and the LD driver 29 are removed.

With this configuration, the first processing circuit 21 of the main substrate 2 can accurately perform the decoding processing of the reproduced signal, the tracking / focusing servo control, etc., as in the first embodiment. In addition, the LD driver 19 of the pickup 1 can control the intensity of the laser light with higher accuracy than in the second embodiment described above. Further, since the drive control of the LD 11 is performed by the pickup 1 except when the information is recorded on the optical disc, there is an advantage that the drive control can be speeded up.

In the pickup 1 having the above structure, the ground terminal of the LD driver 19 that requires a large current is connected to another signal system IC (first and second light receiving circuits 12 and 13).
And the first and second ADCs 15 and 17, etc.) and grounding wiring different from each grounding terminal. With such a configuration, signal distortion can be reduced.

Further, in the optical disk device of each of the above-mentioned embodiments, the signal transmission path and the power supply path provided in the cable 3 connecting the pickup 1 and the main board 2 are arranged and / or electromagnetically separated. You should keep it.
With such a configuration, external noise caused by the drive current to the LD 11 is less likely to affect the signal transmitted from the pickup 1 to the main substrate 2, so that the optical disk device is configured to be more resistant to external noise. You can

In the above description, the optical disc device is taken as an example of the information recording / reproducing device using the head device according to the present invention, but the application of the present invention is not limited to this. The present invention can be applied to various information recording / reproducing devices that record and / or reproduce information on a medium.

[0044]

As described above, the head device according to the present invention includes a sensing circuit for detecting information necessary for recording and / or reproducing information on a medium to obtain an analog signal, and the analog circuit. An analog / digital conversion circuit for converting a signal into a digital signal, and the digital signal is sent to a processing circuit outside the apparatus.

More specifically, the head device according to the present invention, in the head device having the above-described structure, has a light emitting circuit for irradiating the medium with a laser beam, and detects the reflected light from the medium as a sensing circuit. At least one of a first light receiving circuit that obtains an analog signal by using a second light receiving circuit that detects the intensity of laser light to obtain an analog signal and a temperature sensor that detects the ambient temperature of the light emitting circuit and obtains an analog signal It is configured to have one of them.

With such a configuration, a delay or distortion is less likely to occur in a signal transmitted to the outside of the apparatus, and thus even when the capacity of the medium is increased, the density is increased, or the recording / reproducing speed is increased. Thus, it becomes possible to accurately perform various processes in the processing circuit outside the head device.

In the head device having the above structure, the drive circuit for driving the light emitting circuit, the analog signal and //
Alternatively, it may be configured to include a control circuit that controls the drive circuit based on the digital signal. With such a configuration, it becomes possible to control the intensity of the laser light with high accuracy. Further, since the drive control of the light emitting circuit is performed in the head device except when the information is recorded on the medium, there is an advantage that the drive control can be speeded up.

In the head device having the above structure, the sensing circuit and the analog-digital conversion circuit are preferably formed in one chip or one package. With this configuration,
By shortening the wiring distance between the two, it is possible to significantly reduce signal delay and distortion due to wiring capacitance, external noise, and the like. Further, it is possible to contribute to downsizing of the head device.

In the head device having the above structure, it is preferable that each ground terminal of the sensing circuit and the analog-digital conversion circuit is connected to a common ground wiring. With such a configuration, the stray component signal can be reduced, so that stable detection waveforms can be reproduced.

Further, the information recording / reproducing apparatus according to the present invention,
The head device having the above structure, the main substrate on which the processing circuit is formed, and the cable serving as a signal transmission path and a power supply path between the two are configured. With such a configuration, it is possible to realize an information recording / reproducing apparatus capable of coping with speeding up of information recording / reproducing operation with respect to a medium and diversification and complexity of signal processing.

In the information recording / reproducing apparatus having the above structure, the signal transmission path of the cable and the power supply path may be arranged and / or electromagnetically separated. With such a configuration, external noise caused by power supply to the head device is less likely to affect the transmission signal through the cable, and thus the information recording / reproducing device can be further resistant to external noise. .

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical disk device according to the present invention.

FIG. 2 is a diagram showing a first embodiment of an optical disc device according to the present invention.

FIG. 3 is a diagram showing a second embodiment of an optical disc device according to the present invention.

FIG. 4 is a diagram showing a third embodiment of an optical disc device according to the present invention.

FIG. 5 is a diagram for explaining deterioration of settling characteristics due to a flexible cable.

[Explanation of symbols]

1 pickup 11 laser diode (LD) 12 first light receiving circuit 13 second light receiving circuit 14 temperature sensor 2 main board 21 first processing circuit 22 motor driver 23 actuator driver 24 write signal generation circuit 15, 25 first analog-digital conversion Circuit (1st ADC) 16, 26 OPC / APC circuit 17, 27 2nd analog-digital conversion circuit (2nd ADC) 18, 28 2nd processing circuit 19, 29 Laser diode drive circuit (LD driver) 3 Cable 4 Servo motor 5 Actuator

Claims (7)

[Claims] 1. A sensing circuit for detecting an information necessary for recording and / or reproducing information on a medium to obtain an analog signal, and an analog / digital conversion circuit for converting the analog signal into a digital signal. And a head device for transmitting the digital signal to a processing circuit outside the device. 2. A light emitting circuit for irradiating the medium with laser light, a first light receiving circuit as the sensing circuit for detecting reflected light from the medium to obtain an analog signal, and an intensity of the laser light. 2. A second light receiving circuit for detecting and obtaining an analog signal, and a temperature sensor for detecting an ambient temperature of the light emitting circuit to obtain an analog signal, at least one of which is provided. The head device according to 1. 3. A drive circuit for driving the light emitting circuit, and a control circuit for controlling the drive circuit based on the analog signal and / or the digital signal. The head device according to 1. 4. The sensing circuit and the analog-digital conversion circuit are formed in one chip or one package.
The head device according to any one of 1. 5. The head device according to claim 1, wherein each ground terminal of the sensing circuit and the analog-digital conversion circuit is connected to a common ground wiring. . 6. A head device according to any one of claims 1 to 5, a substrate on which the processing circuit is formed, and a cable serving as a signal transmission path and a power supply path therebetween. An information recording / reproducing apparatus comprising: 7. The information recording / reproducing apparatus according to claim 6, wherein the signal transmission path of the cable and the power supply path are separated by arrangement and / or electromagnetically.