JP2642445B2 - Light output control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to, for example, recording information on an optical disc,
The present invention relates to an optical output control device such as an optical disk device for performing reproduction.

2. Description of the Related Art Conventionally, in an information recording / reproducing apparatus such as an optical disc apparatus for optically recording or reproducing information on an optical recording medium such as a write-once or erasable optical disc, a semiconductor laser (optical The information on the optical disk with a relatively small optical output from the output means),
Information is recorded on an optical disk with a relatively large optical output of a certain value or more. Therefore, when an optical output of a certain value or more is generated, indefinite information is written on the optical disk even if it is not intended for recording, and as a result, already recorded information is destroyed. Will be.

In order to prevent the destruction of the information already recorded on the optical disc as described above, the disc is provided with a double recording prevention circuit (Japanese Patent Application Laid-Open No. 54-147006). It is conceived to prevent such damage, and from the viewpoint of preventing physical destruction,
There has been proposed an optical head that prevents an optical head from colliding with an optical disk.

However, such a measure for preventing information destruction of the conventional optical disk apparatus is performed on the assumption that the light output control circuit itself for controlling the light emission of the semiconductor laser does not have a failure, and the failure of the light output control circuit itself is prevented. No particular consideration is given to the case where information on the optical disk is destroyed due to this. That is, in the case where the semiconductor laser abnormally emits light due to the failure of the light output control circuit, there is a possibility that the information recorded on the optical disc may be destroyed even if the information destruction prevention measures described above are taken. If such abnormal light emission is left, there is a problem that the destruction is enlarged.

(Problems to be Solved by the Invention) According to the present invention, if a failure occurs in the optical output control circuit, information recorded on the optical recording medium may be destroyed. An object of the present invention is to provide an optical output control device that does not destroy information recorded on an optical recording medium even if a failure occurs in an optical output control circuit. And

[Means for Solving the Problems] A light output control device according to the present invention includes a light output unit that emits a light beam, and a light output unit that controls the light output of the light beam emitted from the light output unit. Control means, light output detection means for detecting the light output of the light beam emitted from the light output means, and emission of the light beam from the light output means stopped by the control of the first control means. When the light output detecting means detects the light output of the light beam radiated from the light output means in a state in which the first control means is in a state of being detected, the first control means detects an abnormality due to a failure. Second control means for stopping the operation of the first control means when abnormality is detected by the means.

The light output control device of the present invention includes a light output unit that emits a light beam, a first control unit that controls the light output of the light beam emitted from the light output unit, and a light output unit that emits the light beam. Light output detection means for detecting the light output of the light beam; and failure detection means for detecting an abnormality due to a failure in the first control means when the light output detected by the light output detection means is equal to or more than a predetermined value. And third control means for stopping the operation of the first control means when an abnormality is detected by the failure detection means.

The light output control device according to the present invention includes a rotating unit that rotates an optical recording medium on which information is recorded, a light output unit that emits a light beam that irradiates the optical recording medium, and a light emitted from the light output unit. First control means for controlling the light output of the light beam, light output detection means for detecting the light output of the light beam emitted from the light output means, and rotation of the optical recording medium stopped by controlling the rotation means In a state where the light output detecting means detects the light output of the light beam emitted from the light output means, a failure detecting means for detecting an abnormality due to a failure of the first control means; And a fourth control means for stopping the operation of the first control means when an abnormality is detected by the means.

(Function) The present invention controls the light output of the light beam emitted from the light output means by the first control means, and detects the light output of the light beam emitted from the light output means by the light output detection means. When the light output detecting means detects the light output of the radiated light beam in a state where the light beam from the light output means is stopped under the control of the first control means, An abnormality is detected by the failure of the control means, and when the abnormality is detected, the operation of the first control means is stopped.

According to the present invention, the light output of the light beam emitted from the light output means is controlled by the first control means, and the light output of the light beam emitted from the light output means is detected by the light output detection means. When the light output detected by the output detection means is equal to or more than a predetermined value, abnormality detection due to a failure of the first control means is performed, and when the abnormality is detected, the operation of the first control means is stopped. It has become.

According to the present invention, an optical recording medium on which information is recorded is rotated by a rotating means, and a light output of a light beam emitted from a light output means for emitting a light beam for irradiating the optical recording medium is used as a first light output.
The light output of the light beam emitted from the light output means is detected by the light output detection means, and the rotation of the optical recording medium is stopped by the control of the rotation means. When the output detection means detects the light output of the light beam emitted from the light output means, it performs abnormality detection due to the failure of the first control means, and when the abnormality is detected, the operation of the first control means Is to be stopped.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 4 shows a schematic configuration of a light output control device of the present invention, for example, an optical disk device. That is, the optical disk (optical recording medium) 1 is formed by coating a metal film layer such as tellurium or bismuth in a donut shape on the surface of a circular substrate made of, for example, glass or plastics.

The optical disc 1 is a spindle motor (rotating means)
2 to rotate. The drive of the spindle motor 2 is controlled by a motor control circuit 3, and the start and stop of rotation are controlled in accordance with a rotation command signal S1 from the control circuit 4.

The control circuit 4 is constituted by a microcomputer or the like, and controls the rotation of the spindle motor 2 and controls the entire apparatus.

An optical head 5 is provided below the optical disc 1. The optical head 5 records or reproduces information on or from the optical disk 1. The optical head 5 includes a semiconductor laser oscillator 6, a collimator lens 7, a beam splitter 8,
It comprises an objective lens 9, a condenser lens 10, a photodetector 11, a photodiode 12, and the like.

The semiconductor laser oscillator (optical output means) 6 generates divergent laser light in accordance with the drive signal S2 from the optical output control circuit 15, and should be written when information is written on the recording film of the optical disk 1. A strong laser light whose light intensity is modulated according to the information is generated, and a weak laser light having a constant light intensity is generated at the time of reproduction in which the information is read from the recording film of the optical disc 1. .

The divergent laser light generated from the semiconductor laser oscillator 6 is converted into a parallel light beam by the collimator lens 7 and guided to the beam splitter 8. The laser light guided to the beam splitter 8 is reflected by the beam splitter 8 and is incident on an objective lens 9.
Is focused toward the recording film of the optical disc 1.

The objective lens 9 is movably supported in its optical axis direction and in a direction orthogonal to the optical axis. When the objective lens 9 is positioned at a predetermined position, the convergence of light passing through the objective lens 9 is improved. The laser beam is projected on the surface of the recording film of the optical disk 1, and a minimum beam spot is formed on the surface of the recording film of the optical disk 1. In this state, the objective lens 9 is kept in a focused state and a focused track state, and writing and reading of information can be performed.

The divergent laser light reflected from the recording film of the optical disc 1 is converted into a parallel light beam by the objective lens 9 at the time of focusing, and is returned to the beam splitter 8 again. Then, the light passes through the beam splitter 8 and is imaged on the photodetector 11 by the condenser lens 10.

The photodetector 11 is configured by a photodetection cell that converts light formed by the condenser lens 10 into an electric signal. The electric signal photoelectrically converted by the photodetector 11 is sent to the signal processing circuit 13 as a reproduction signal.

In addition, a photodiode 12 as a photoelectric conversion element is provided on the side of the semiconductor laser oscillator 6 opposite to the light emitting port of the recording or reproducing laser light. The photodiode 12 irradiates the monitor light from the semiconductor laser oscillator 6 to convert the monitor light into an electric signal (photocurrent), and controls the light output as an optical output monitor signal S3 of the semiconductor laser oscillator 6. The circuit 15 is supplied.

The optical head 5 can be moved in the radial direction of the optical disc 1 by a moving mechanism (not shown) constituted by, for example, a linear motor or the like, and moved to a target track to be recorded or reproduced by the moving mechanism. It is supposed to.

The signal processing circuit 13 performs processing such as amplification and binarization of the reproduction signal photoelectrically converted by the photodetector 11. The reproduced signal binarized by the signal processing circuit 13 is supplied to a header separation reading circuit 14. The header separating and reading circuit 14 separates the information of the header portion and the information of the data portion from the reproduced signal read from the optical disc 1 and binarized, and sends the separated information to the control circuit 4.

The light output control circuit (first control means) 15 receives the light output monitor signal S3 output from the semiconductor laser oscillator 6 and performs feedback control to maintain the light output of the semiconductor laser oscillator 6 at a constant value. The details will be described later.

The failure detection circuit (detection means) 16 is a light output control circuit
Fifteen various failures are detected, and the detection result is supplied to the control circuit 4 while being supplied to the relay circuit 17. Details of the failure detection circuit 16 will be described later.

Relay circuit 17, of the voltage source E ₀ supplied from a power supply device (not shown), independently of the other circuits, the semiconductor laser oscillator 6, the photodiode 12, and optical output control circuit
This shuts off the voltage source E supplied only to the power supply 15 and is controlled to open and close based on a failure detection signal S4 from the failure detection circuit 16.

Next, details of the light output control circuit 15 and the failure detection circuit 16 will be described with reference to FIG.

First, the light output control circuit 15 is configured as follows. That is, the current-voltage conversion circuit 20 is
The optical output monitor signal S3, which is photoelectrically converted at 12, and is taken out as a current signal, is input, and the light intensity of the photodiode 12, that is, the voltage signal Ve corresponding to the optical output of the semiconductor laser oscillator 6 is inputted.
_It is converted to ₀ . The voltage signal Ve ₀ output from the current / voltage conversion circuit 20 is supplied to the error amplifier 21. The error amplifier 21, the voltage signal Ve ₀ as one input, the reference voltage Vs generated by the constant voltage source (not shown) as the other input, these two voltages Ve ₀ and Vs
Are compared, and the difference is amplified and output as an error signal S5. This error signal S5 is supplied to the switching circuit 22. The reference voltage Vs is a constant voltage for obtaining an optical output required for reproduction, and is constant from the semiconductor laser 6 by performing feedback control so that the voltage signal Ve ₀ approaches the reference voltage Vs, as described later. Is obtained.

The switching circuit 22 controls opening and closing of a control loop according to an operation mode such as recording or reproduction, and is configured as shown in detail in FIG. That is, the error signal S5 output from the error amplifier 21 is switched via the resistor R7.
25 is connected to one end of switch 25.
It is connected to the non-inverting input terminal of the operational amplifier 27 via R8. The opening and closing of this switch 25 is controlled by a control loop opening and closing signal S10 output from the control circuit 4. The other end of the switch 25 (one end of the resistor R8)
Is grounded through a switch 26.
The opening and closing are controlled by a reproduction light output control signal S11 output from the control circuit 4. The above resistor R8
, That is, the non-inverting input terminal of the operational amplifier 27 is grounded via a drive voltage holding capacitor.
Further, the operational amplifier 27 functions as a buffer, and its output signal S6 is supplied to the base of the transistor 23.

The transistor 23 generates a laser beam having a constant value of weak light intensity as reproduction light, so that a signal supplied to its base is
The semiconductor laser oscillator 8 is driven according to S6. The emitter of the transistor 23 is grounded via the resistor R1. The transistor 24 drives the semiconductor laser oscillator 6 according to a recording signal S7 supplied to its base in order to generate a laser beam having a high intensity according to recording data as recording light. The emitter of the transistor 24 is grounded via the resistor R2.

Next, the operation of the light output control circuit 15 configured as described above will be described. First, the control loop opening / closing signal S10 output from the control circuit 4 is set to a high level (hereinafter, referred to as “H level”) only when information recorded on the optical disc 1 is reproduced, and at other standby or information levels. Is low level (hereinafter, referred to as “L level”).
Is controlled so that This control loop opening / closing signal S10
Is set to the H level, the switch 25 is turned on, and the control loop is closed. On the other hand, the reproduction light output control signal
S11 is controlled so as to be at the L level during standby and at the H level during information reproduction and recording. The switch 26 is turned on when the reproduction light output control signal S11 is at L level, and is turned off when it is at H level.

That is, during standby, the control loop opening / closing signal S10
And the reproduction light output control signal S11 are both at L level,
Therefore, the switch 25 is off and the switch 26 is on. As a result, the non-inverting input terminal of the operational amplifier 27 is grounded, and its output signal S6 becomes 0 volt. Therefore, the transistor 23 is turned off, and no laser light is generated from the semiconductor laser oscillator 6. On this occasion,
Of course, the recording signal S7 is not supplied, and therefore, the transistor 24 is also off.

At the time of reproduction, the control loop opening / closing signal S10 and the reproduction light output control signal S11 are both set to H level by the control circuit 4, so that the switch 25 is turned on and the switch 26 is turned off. As a result, the switching circuit 15 outputs a signal S6 corresponding to the input error signal S5, and the control loop is closed. That is, when the error signal S5 output from the error amplifier 21 is supplied to the base of the transistor 23 via the switching circuit 22, the drive signal S2 flows to the collector of the transistor 23, and the semiconductor laser oscillator 6 emits light. . The optical output of the semiconductor laser oscillator 6 is photoelectrically converted by the photodiode 12, and the optical output monitor signal S3
Is supplied to the current-to-voltage conversion circuit 20. In the current-voltage conversion circuit 20 converts the optical output monitor signal S3 to the voltage signal Ve _0, and supplies to the error amplifier 21. In the error amplifier 21,
Compares the reference voltage Vs and the voltage signal Ve ₀ which is set in advance, and outputs the error component as an error signal S5. The error signal S5, the when the voltage signal Ve ₀ is larger than the reference signal Vs to reduce the light output of the semiconductor laser oscillator 6, a large light output of the semiconductor laser oscillator 6 is smaller the voltage signal Ve ₀ is the reference signal Vs The feedback control acts so that the reference voltage Vs and the voltage signal Ve ₀ become equal, whereby the optical output of the semiconductor laser oscillator 6 is kept constant.

At the time of recording, the control loop opening / closing signal S10 is at the L level and the reproduction light output control signal S11 is at the H level, so that both the switches 25 and 26 are turned off. In this state,
The drive voltage holding capacitor 28 has an operational amplifier during playback.
The voltage supplied to the non-inverting input terminal 27 is held, and at the time of reproducing the header information performed before recording, the transistor 23 is driven by the held voltage to obtain a reproduction light. . In this state, a recording signal S7 corresponding to the information to be recorded is supplied to the base of the transistor 24, so that a drive signal S2 flows to the collector of the transistor 24, thereby causing the semiconductor laser 6 to emit light and record information on the optical disc 1. I do.

Next, the failure detection circuit 16 is configured as follows. First, the places to be monitored inside the optical output control circuit 15 are the output terminal of the current-voltage conversion circuit 20, the emitter terminal of the transistor 23, and the emitter terminal of the transistor 24. The voltage signal Ve ₀ appearing at the output terminal of the current-voltage conversion circuit 20 is
The voltage is extracted as a voltage signal Ve via a resistor R3 having a value sufficiently larger than the output resistance. The voltage signal appearing at the emitter terminal of the transistor 23 is taken out as a voltage signal Vf via a resistor R4 having a value sufficiently larger than the emitter resistance R1, and the voltage signal appearing at the emitter terminal of the transistor 24 is derived from the emitter resistor R2. The voltage signal Vg is taken out via a resistor R5 having a sufficiently large value. The resistors R3, R4, and R5 are respectively connected to the output terminal of the current / voltage conversion circuit 20, the transistor 23,
, And the emitter terminal of the transistor 24. As described above, when taking out a signal from a predetermined portion of the optical output control circuit 15, by interposing a sufficiently large resistor provided near the signal source, the optical output control circuit 15 associated with the addition of the failure detection circuit 16 Is minimized, and a decrease in the reliability of the optical output control circuit 15 can be prevented.

The voltage signal Ve extracted via the resistor R3 is
The signals are supplied to the non-inverting inputs (+ terminals) of 30 and 32, and are supplied to the inverting input terminals (-terminals) of the comparator 31.

The reproduction light lower limit voltage Va supplied from a constant voltage source (not shown) is input to the inverting input terminal of the comparator (second and fourth control means) 30. When the voltage signal Ve is lower than the reproduction light lower limit voltage Va, an L level signal is output. When the voltage signal Ve is higher than the reproduction light lower limit voltage Va, an H level signal is output.

A non-inverting input terminal of the comparator (third control means) 31 has a reproduction light upper limit voltage supplied from a constant voltage source (not shown).
Vb is input. And the voltage signal Ve
Is higher than the reproduction light upper limit voltage Vb, the L level signal is
When the signal Ve is smaller than the reproduction light upper limit voltage Vb, an H level signal is output.

The recording light upper limit voltage Vc supplied from a not-shown constant voltage source is input to the inverting input terminal of the comparator (third control means) 32. When the voltage signal Ve is lower than the recording light upper limit voltage Vc, an L level signal is output, and when the voltage signal Ve is higher than the recording light upper limit voltage Vc, an H level signal is output.

The output of the comparator 30 is supplied to one input of an AND gate (second control means) 35, and the other input of the AND gate 35 has a reproduction light output control signal S
A signal obtained by inverting 11 by an inverter 36 is input. Then, the signal S30 obtained by the AND operation by the AND gate 35 is supplied to the NOR gate 37 and the latch 38.

The AND gate (third control means) 39 performs a logical AND operation on one input of the reproduced light output control signal S11 and the other input of the output signals of the comparators 30 and 31 by a NAND gate 40. An inverted signal is input. The signal S31 ANDed by the AND gate 39 is NOR
It is supplied to a gate 37 and a latch 38.

The output signal of the comparator 32 is input to one input of an AND gate (third control means) 41, and the recording control signal S12 supplied from the control circuit 4 is input to the other input. ing. The output signal S32 obtained by the AND operation by the AND gate 32 is supplied to the NOR gate 37 and the latch 38.

Further, the output signal of the comparator 30 is input to one input of the AND gate 42 (fourth control means), and the rotation command signal S1 supplied from the control circuit 4 is input to the other input. Has become. The signal S33 obtained by the AND operation by the AND gate 42 is supplied to the NOR gate 37 and the latch 38. The rotation command signal S1 is output as an L level when instructing the rotation of the spindle motor 2, and as an H level when instructing to stop.

A comparison voltage Vd supplied from a not-shown constant voltage source is input to the inverting input terminals of the comparators 33 and 34. This comparison voltage Vd is applied to transistors 23 and 24
Is a relatively low voltage for detecting the presence or absence of an emitter current. To the non-inverting input terminal of the comparator 33, a voltage extracted from the emitter of the transistor 23 is input as an emitter voltage signal Vf via a resistor R4.
The output of the comparator 33 is supplied to one input of an AND gate 43, and the other input of the AND gate 43 is connected to the comparator 30.
Output is supplied. The output signal S34 ANDed by the AND gate 43 is supplied to the NOR gate 37 and the latch 38.

The non-inverting input terminal of the comparator 34 has a transistor
The voltage extracted from the 24 emitters is input as an emitter voltage signal Vg via a resistor R5. The output of the comparator 34 is supplied to one input of an AND gate 44, and a signal obtained by inverting the recording control signal S12 by an inverter 45 is input to the other input of the AND gate 44. It has become. And AND gate 44
The signal S35 ANDed with is NOR gate 37 and latch
38 are supplied.

The output signal S30 of the AND gates 35, 39, 41, 42, 43, 44
To S35 and a signal S36 directly output from the control circuit 4.
(Details will be described later) are ORed by the NOR gate 37 and inverted, and supplied to the delay element 45 and one input of the OR gate 46 as an error signal S40. The delay element 45 delays the input error signal S40 by a predetermined time Td and outputs the delayed signal.
S41 is supplied to the other input of the OR gate 46 and the latch 38. Then, the signal whose logical sum is obtained by the OR gate 46 is supplied to the base of the transistor 47 via the resistor R9. The on / off of the transistor 47 is controlled by a signal from the OR gate 46, and the contact of the relay circuit 17 is connected or opened by a failure detection signal S4 flowing through its collector.

The fixed time Td is a time during which the destruction of information recorded on the optical disc 1 can be tolerated, and more specifically, a limit time during which a burst error can be corrected by an error correction circuit provided in the information recording / reproducing apparatus. That is, even if the information on the optical disc 1 is destroyed, the time corresponding to the amount of correction by the error correction circuit to obtain correct information is set as the limit value. It is determined by time.

The latch 38 uses the signal S41 generated by the delay element 45 as a latch timing signal, and
1, 42, 43 and 44 are latched. The output of the latch 38 is sent to the control circuit 4,
Used for analysis and display of the cause of failure.

Next, the operation of the failure detection circuit 16 configured as described above will be described with reference to the timing chart of FIG.

The operation state of this device is roughly classified into three types, and is defined by a control loop opening / closing signal S10, a reproduction light output control signal S11, and a recording control signal S12 output by the control circuit 4, respectively. That is, as shown in FIG. 3, the first state A is a period in which the output of the reproduction light and the recording light is turned off, such as during standby, and the control loop opening / closing signal S10, the reproduction light output control signal S11, and the recording The control signals S12 are all at the L level. The second state B is a period during which the reproduction light output is turned on during recording, the recording light output is turned off, and a small light output required for signal reproduction is generated, and the control loop opening / closing signal S10 and the reproduction light output control signal S11 Is the H level, the recording control signal S12
Is in the L level state. The third state C is a period in which the reproduction light output is turned on during recording, the recording light output is turned on, and a large light output required for recording is emitted.
S10 is at the L level, the reproduction light output control signal S11 is at the H level, and the recording control signal S12 is at the H level. Hereinafter, the failure detection operation in each of these states will be described.

First, the failure detection in the mode in which the light emission output is detected in the state where the reproduction light output is off will be described. The 3 A ₁ period in the figure shows a state in which the semiconductor laser oscillator 6 is not driven, therefore, the photodiode
There is no photoelectric conversion output from 12, and the voltage signal Ve is normally kept at 0 volt. However, as shown in FIG. 2 (d), when a high voltage signal Ve than the reproduction beam lower limit voltage Va at time t1 of A ₂ periods by some failure of the optical output control circuit 15 is generated, the output of the comparator 30 An H level signal appears at the terminal and is supplied to one input of the AND gate 35. At this time, the reproduction light output control signal S11 is inverted by the inverter 36 and input to the other input terminal of the AND gate 35 as an H level signal. Accordingly, a signal S30 rising at time t1 is output from the output of the AND gate 35, as shown in FIG.
Is inverted by passing through the NOR gate 37 and supplied to the OR gate 46 and the delay element 38 as an error signal S40. If the signal S30 does not return to the L level during the predetermined time Td, an L level signal is output to the output of the OR gate 46 and supplied to the base of the transistor 47 via the resistor R9. As a result, the failure detection signal S4 flowing to the collector of the transistor 47 is cut off, the contact of the relay circuit 17 is opened, and the voltage source E supplied to the semiconductor laser oscillator 6, the photodiode 12, and the light output control circuit 15 is cut off. You. As a result, the emission output of the semiconductor laser 6 stops,
It is possible to prevent information on the optical disc 1 from being destroyed by light emission due to a failure. On the other hand, the output signal S30 of the AND gate 35 is latched by the latch 38 at the falling timing of the signal S41 output from the delay element 45 as a cause of failure. The signal from the latch 38 is supplied to the control circuit 4 and analyzed by the control circuit 4 to turn on the abnormal lamp,
It is used for announcing anomalies such as sounding a buzzer or displaying a message.

Next, detection of a failure in a mode in which the light output is out of a certain range when the reproduction light output is on will be described. In the period B _{1 in} FIG. 3, the voltage signal from the photodiode 12 is
Ve is between the reproduction light lower limit voltage Va and the reproduction light upper limit voltage Vb, and indicates a state in which normal operation is performed. In such a normal state, as shown in B ₂ periods of FIG. 3 (d), when a low voltage signal Ve than the reproduction beam lower limit voltage Va at time t5 due to some failure of the optical output control circuit 15 is generated, compared An L level signal appears at the output terminal of the device 30, and a NAND gate
By being supplied to one input of 40, its output becomes H level, which is supplied to one input of AND gate 39. At this time, the reproduction light output control signal S11 is input to the other input terminal of the AND gate 39 as an H level signal. Accordingly, as shown in FIG. 3 (e), a signal S31 rising at time t5 is output from the output of the AND gate 39, and this signal S31 is inverted by passing through the NOR gate 37 to be inverted to generate the error signal S40. Is supplied to the OR gate 46 and the delay element 38. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. Here, the supply of the voltage source E is stopped even though the voltage signal Ve is 0 volt, because both the control loop opening / closing signal S10 and the reproduction light output control signal S11 are at H level. Has been commanded, the voltage signal Ve is 0
If the voltage is in volts, the error amplifier 21 acts to perform the maximum drive with respect to the reference voltage Vs, and the semiconductor laser oscillator 6 may cause excessive light emission. As a result, an emergency failure in the system from the photodiode 12 to the current-voltage conversion circuit 20 can be detected, and the information on the optical disc 1 can be prevented from being destroyed by abnormal light emission due to the failure. Also,
The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

On the other hand, as shown in B ₃ periods of FIG. 3 (d), when a high voltage signal Ve than the reproduction beam upper limit voltage Vb at time t6 due to some failure of the optical output control circuit 15 is generated,
An H-level signal appears at the output terminal of the comparator 31, and is supplied to the other input of the NAND gate 40 to output an H-level signal to its output, which is supplied to one input of the AND gate 39. At this time, the reproduction light output control signal S11 is input to the other input terminal of the AND gate 39 as an H level signal. Therefore, as shown in FIG. 3 (e), a signal S31 rising at time t6 is output from the output of the AND gate 39, and this signal S31 is inverted by passing through the NOR gate 37 and is inverted to generate the error signal S40. Is supplied to the OR gate 46 and the delay element 38. Hereinafter, in the same operation as above,
The contact of the relay circuit 17 is opened and the voltage source E is cut off. As a result, the optical output is stopped, and it is possible to prevent information on the optical disc 1 from being destroyed due to abnormal light emission due to a failure.
The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

Next, detection of a failure in a mode in which the light output is greater than or equal to a certain value when the recording light output is on will be described. C ₁ period in FIG. 3, the voltage signal from the photodiode 12
Ve is between the reproduction light upper limit voltage Vb and the recording light upper limit voltage Vb, and indicates a state where the recording operation is normally performed. In such a performance state, as shown in B ₂ periods of FIG. 3 (d), when a high voltage signal Ve than recording light upper limit voltage Vc at time t8 by some failure of the optical output control circuit 15 is generated, compared An H level signal appears at the output terminal of the
It is supplied to one input of the D gate 41. At this time, the recording control signal S12 is input as an H level signal to the other input terminal of the AND gate 41. Therefore, AND gate 4
As shown in FIG. 3 (e), a signal S32 which rises at time t8 is output from the output of the NOR gate 37.
Is inverted by passing through O as an error signal S40.
It is supplied to the R gate 46 and the delay element 38. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. As a result, the optical output is stopped, and it is possible to prevent information on the optical disc 1 from being destroyed due to abnormal light emission due to a failure. The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

Next, detection of a failure in a mode in which the light output becomes a certain value or more while the rotation of the spindle motor 2 is stopped will be described. In general, when laser light is irradiated when the optical disk is not rotating or has not reached a predetermined number of revolutions, the irradiated energy becomes a value equal to or more than a specified value, and recorded information is destroyed. I have. Therefore, when the spindle motor 2 is not rotating or has not reached the predetermined number of rotations, the rotation designation signal S1 is set to H level.
And the optical output of the semiconductor laser oscillator 6 is stopped. Therefore, it is determined that the presence of the voltage signal Ve based on the light emission output in such a state is due to the failure of the light output control circuit 15. That is, the light output control circuit 15
If a voltage signal Ve that is higher than the reproduction light lower limit voltage Va is generated due to some kind of failure, the output terminal of the comparator 30
A level signal appears and is provided to one input of AND gate 42. At this time, the rotation command signal S1 of the spindle motor 2 is input to the other input terminal of the AND gate 39 as an H level signal. Therefore, an H-level signal S33 is output from the output of the AND gate 42, and this signal S33 is
The error signal S4 is inverted by passing through the gate 37.
It is supplied to the OR gate 46 and the delay element 38 as 0. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. As a result, the light output is stopped, and it is possible to prevent the information on the optical disc 1 from being destroyed due to abnormal light emission due to a failure. The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

As described above, the presence or absence of the voltage signal Ve according to the optical output of the semiconductor laser 6 or the magnitude of the voltage signal Ve is detected, and if this detection result corresponds to the one that destroys the information stored in the optical disc 1, the relay Since the contact of the circuit 17 is opened to shut off the voltage source E and stop the light emission of the semiconductor laser 6, the information stored on the optical disk 1 can be prevented from being destroyed with sufficient certainty. It has become.

Next, detection of a failure in a mode in which information on the optical disc 1 is destroyed even though the reproduction light output is off and the voltage signal Ve from the current-voltage conversion circuit 20 is 0 volt. explain. In other words, the failure detection circuit in the mode in which the light emission output is detected in spite of the above-described generated light output off state is always set to 0 as the voltage signal Ve when there is a failure in the system that generates the voltage signal Ve. In some cases, bolts can be obtained, which is not enough. In such a case, the operation is as follows. That is, in FIG.
A ₃ period is a state in which the semiconductor laser oscillator 6 is not driven, the transistor 23 is turned off and the emitter voltage signal Vf is in a normal state that is maintained at 0 volts. In this state, as shown in A ₂ period in FIG (d),
Assuming that a voltage signal Vf higher than the comparison voltage Vd is generated at time t2 due to some failure of the light output control circuit 15, an H level signal appears at the output terminal of the comparator 33, and
It is supplied to one input of a D gate 43. At this time, the reproduction light output control signal S11 is inverted by the inverter 36 and input to the other input terminal of the AND gate 43 as an H level signal. Therefore, as shown in FIG. 3 (e), a signal S34 rising at time t2 is output from the output of the AND gate 43, and this signal S34 is inverted by passing through the NOR gate 37 to be inverted to generate an error signal S40. Is supplied to the OR gate 46 and the delay element 38. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. As a result, the optical output is stopped, and it is possible to prevent information on the optical disc 1 from being destroyed due to abnormal light emission due to a failure. As described above, since the abnormality detection is performed twice, it is possible to more reliably prevent the information on the disk 1 from being destroyed. The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

Similarly, A ₄ periods in FIG. 3 is also a state where the semiconductor laser oscillator 6 is not driven, therefore, the transistor 24 is turned off, that the emitter voltage signal Vg is maintained at 0 volts It is in a normal state. In such a state,
As shown in A ₄ period in FIG (d), when a high voltage signal Vg than the comparison voltage Vd at time t3 due to some failure of the optical output control circuit 15 is generated, the output terminal of the comparator 34 H A level signal appears and is provided to one input of AND gate 44. At this time, the recording control signal S12 is inverted by the inverter 45 to the other input terminal of the AND gate 43,
It is input as a level signal. Therefore, AND
As shown in FIG. 3 (e), the output of the gate 44
A signal S35 rising at t3 is output, and this signal S35 is inverted by passing through a NOR gate 37 to generate an error signal S40.
Is supplied to the OR gate and the delay element. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. This stops the light output,
The information on the optical disk 1 can be prevented from being destroyed by abnormal light emission due to a failure. The failure factor is also latched by the latch 38 by the same operation as described above, and is used for failure analysis performed later.

Next, failure detection when the continuity of the header address at the time of recording is lost will be described with reference to FIG.
That is, when performing the recording operation, first, the control circuit 4
Are provided with position information (header address information) on the optical disk 1 for recording. Thereby, the optical head 5 moves to the target position,
Tracking and focusing are performed. In parallel with the above operation, the block number i of the target position is set as an initial value in a counter (not shown) provided in the control circuit 4 (step S1). Next, tracking and focusing are completed,
When the track enters the combined track state and access to the optical disk 1 becomes possible, the header address information is read (step S2). Then, it is checked whether or not the block number included in the header address information matches the content i of the counter (step S3). If they match, the process proceeds to step S4 to increment the content of the counter,
The recording signal S7 according to the given information is output to the optical output control circuit 15
Then, a laser beam corresponding to the information is generated and recording is performed (step S5). Next, it is checked whether or not all the specified recordings have been completed (step S).
6) If not completed, return to step S2 and repeat the above operation again.

On the other hand, if the content i of the counter does not match the block number in step S3, it is determined that the continuity of the header address has been lost due to, for example, an off-track or the like.
A level laser off signal S36 is output, and the process ends. This signal S36 is, as shown in FIG.
Is inverted by passing through O as an error signal S40.
It is supplied to the R gate 46 and the delay element 38. Thereafter, by the same operation as described above, the contact of the relay circuit 17 is opened and the voltage source E is cut off. As a result, the light output is stopped, and the destruction of information on the optical disc 1 due to the off-track can be prevented.

As described above, various failures of the light output control circuit 15 are detected by the failure detection circuit 16, and when an abnormality is detected, the power supply to the semiconductor laser 6, the photodiode 12, and the light output control circuit 15 is shut off. Since the light emission of the semiconductor laser is reliably stopped, the information recorded on the optical disk 1 can be reliably prevented from being destroyed. Further, the cause of the failure is stored in the latch 38 and is used for failure analysis performed later, so that failure detection is easy and the cause of the failure can be easily clarified.

Further, when extracting a monitor signal for performing a failure detection from a predetermined portion of the light output control circuit 15, the failure detection circuit 16 is provided because the monitoring is performed through the resistors R3, R4, and R5 having high resistance values. This has no adverse effect on the optical output control circuit, and can prevent a decrease in reliability.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an optical output control device that does not destroy information recorded on an optical recording medium due to a failure of an optical output control circuit.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing a schematic configuration of an electric circuit of an optical disk device, FIG. 2 is a block diagram of a switching circuit, and FIG. FIG. 4 is a schematic configuration diagram of an optical disk device, and FIG. 5 is a flowchart for explaining failure detection during a recording operation. DESCRIPTION OF SYMBOLS 1 ... Optical disk (optical recording medium), 2 ... Spindle motor (rotating means), 3 ... Motor control circuit, 4 ... Control circuit, 5 ... Optical head, 6 ... Semiconductor laser oscillator (optical output means) , 11 photodetector, 12 photodiode, 13 signal processing circuit, 14 header separation reading circuit, 15 light output control circuit (first control means), 16
Failure detection circuit (detection means), 17 relay circuit (second,
.., Comparators (second and fourth control means), 31, 32... Comparators (third control means), 35
... AND gate (second control means), 39, 41 ... AND gate (third control means), 42 ... AND gate (fourth control means), 38 ... latch, R3, R4, R5 ……resistance.

Claims (3)

(57) [Claims] A light output unit for emitting a light beam; a first control unit for controlling a light output of the light beam emitted from the light output unit; and a light beam emitted from the light output unit A light output detecting means for detecting an output, and in a state where emission of a light beam from the light output means is stopped by control by the first control means,
When the light output detection means detects the light output of the light beam emitted from the light output means, a failure detection means for detecting an abnormality due to a failure of the first control means, and an abnormality is detected by the failure detection means. A second control means for stopping the operation of the first control means at this time. 2. Light output means for emitting a light beam, first control means for controlling the light output of the light beam emitted from the light output means, and light of the light beam emitted from the light output means Optical output detection means for detecting an output; failure detection means for performing an abnormality detection due to a failure of the first control means when an optical output detected by the optical output detection means is equal to or more than a predetermined value; And a third control means for stopping the operation of the first control means when an abnormality is detected by the means. 3. A rotating means for rotating an optical recording medium on which information is recorded, a light output means for emitting a light beam for irradiating the optical recording medium, and a light beam emitted from the light output means. First control means for controlling the output, light output detection means for detecting the light output of the light beam emitted from the light output means, and a state in which the rotation of the optical recording medium is stopped by the control of the rotation means In the above, when the light output detection means detects the light output of the light beam emitted from the light output means, a failure detection means for detecting an abnormality due to a failure of the first control means, and an abnormality detection by the failure detection means And a fourth control means for stopping the operation of the first control means when the operation is performed.