JPH08315395A - Disk player - Google Patents

Abstract

PURPOSE: To remove dust, etc., stuck to an objective lens with a simple constitution before a sound skip and a malfunction occur. CONSTITUTION: The dirt on objective lens 28 based on reflection light from a disk passing through the objective lens 28 of an optical pickup is detected by an LSI 29A as a lens dirt detection means, and the objective lens 28 is made to vibrate wit a prescribed drive signal by a drive circuit 26 as an objective lens vibration means, and the dust, etc., stuck to the lens surface is shaken off. Thus, the objective lens 28 is vibrated bit by bit e.g. in the tracking direction by the prescribed drive signal without changing existing constitution, and since the dust, etc., stuck to the objective lens 28 is shaken off, the dust, etc., stuck to the objective lens 28 is removed with the simple constitution before a sound skip and a malfunction occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc player having a function of automatically removing dust and the like adhering to an objective lens of an optical pickup.

[0002]

2. Description of the Related Art A CD player or an L for reading information recorded on a disc by an optical pickup.
In a disc player such as a D player, if dust or the like adheres to the objective lens, the S / N of the disc reading light is deteriorated, and problems such as skipping of sounds and malfunctions occur.

For this reason, methods such as wiping the objective lens with a cotton swab or cleaning the objective lens with a cleaning disk have been adopted. In particular, the slot-in type, which is widely used for vehicles, is difficult to wipe off with a cotton swab or the like because of its structure, and therefore a cleaning disk is mostly used.

By the way, a compact cassette (C cassette)
Some players such as VTRs and the like have a cleaning mechanism provided in advance inside the player body.

[0005]

As described above, in the above-mentioned conventional disc player, since dust and the like adhering to the objective lens may cause sound skipping and malfunction, the objective lens may be swabbed or swallowed. It is necessary to clean with a cleaning disc or the like. Regarding the cleaning timing in this case, it is possible to notice the cleaning timing for the first time by noticing abnormalities due to sound skips, malfunctions, and the like occurring during disk reproduction.

For this reason, for example, during recording from a CD to a recordable disc or a compact cassette, if sound skipping or malfunction occurs due to dust or the like adhering to the objective lens, recording will be performed. It is inconvenient because it requires repair.

Further, since it is necessary to clean the objective lens with a cotton swab, a cleaning disk, or the like, it is troublesome, and the cleaning work is complicated.

Further, in a compact cassette (C-cassette) deck, a VTR, etc., in which a cleaning mechanism is previously built in the player main body, the mechanical structure is complicated and the number of parts is increased. It also hinders reduction.

Furthermore, since the objective lens of the optical pickup used in the disc player is cantilevered by a leaf spring, wire suspension or the like, cleaning of a cotton swab or a cleaning disc against the lens surface of the objective lens is performed. Even when the brush comes into contact, the objective lens escapes due to the supporting structure such as the leaf spring and the wire suspension, so that it is difficult to strongly wipe the lens surface.

The present invention has been made in consideration of such a situation, and before the occurrence of sound skipping or malfunction of dust and the like adhering to an objective lens with a simple structure without adding a new mechanism. It is an object of the present invention to provide a disc player that can be removed.

[0011]

In order to achieve the above-mentioned object, the present invention provides a disc player having an optical pickup, wherein the optical pickup is based on the reflected light from the disc passing through the objective lens of the optical pickup. It is characterized in that it has a lens dirt detecting means for detecting dirt of the objective lens and an objective lens vibrating means for vibrating the objective lens based on a detection result of the lens dirt detecting means.

[0012]

According to the disk player of the present invention, when the dirt on the objective lens is detected by the lens dirt detecting means based on the reflected light from the disk passing through the objective lens of the optical pickup, the objective lens vibrating means moves the objective lens. Is vibrated.

Therefore, the objective lens can be oscillated in small increments in the tracking direction by a predetermined drive signal without changing the existing structure, and dust and the like adhering to the objective lens can be shaken off.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 show a level detection circuit for detecting dirt based on an RF signal according to an embodiment of the disc player of the present invention.

As shown in these figures, an RF signal, which is a detection signal of reflected light from the disk detected by a photodetector (not shown), is taken into the peak hold circuit 1 and the bottom hold circuit 2, and these peak hold circuit 1 is carried out. When the peak signal and the bottom signal are obtained by the bottom hold circuit 2, the difference signal is obtained by the arithmetic circuit 3, and the comparison circuit 4 compares the reference signal with the reference value 5.

However, since such an RF signal is obtained in the tracking closed state and is obtained as a signal including an envelope in the tracking open state as shown in, a peak time constant that does not follow the envelope is selected. By the peak level y
And the bottom level x can be detected.

FIG. 3 illustrates a case where the tracking error level is detected by the same level detection circuit as in FIG.

That is, the sine wave tracking error (TE) signal of amplitude x and y, which is a detection signal from a photodetector (not shown), is represented by the peak hold circuit 1.
When the peak hold circuit 1 and the bottom hold circuit 2 extract the peak level y and the bottom level x, a difference signal is obtained by the arithmetic circuit 3 and a reference signal is obtained by the comparison circuit 4. A comparison with the value 5 is made.

FIG. 4 shows the focus error level in FIG.
The case where detection is performed by the same level detection circuit as in FIG.

As shown in the figure, a focus error (FE) which is a detection signal from a photodetector (not shown).
When the signal is taken into the peak hold circuit 1 and the bottom hold circuit 2 and the peak level and the bottom level are extracted by the peak hold circuit 1 and the bottom hold circuit 2, the difference between the peak signal and the bottom signal is calculated by the arithmetic circuit 3. A signal is obtained and the comparison circuit 4 compares it with the reference value 5.

The peak hold circuit 1 and the bottom hold circuit 2 are controlled by using a signal f _ok obtained by comparing the RF signal with a certain threshold value. That is, f _ok
The peak hold circuit 1 and the bottom hold circuit 2 are reset at the rising edge of, and sampling is performed at the falling edge.

FIG. 5 shows a dirt detection circuit for detecting dirt on the basis of the comparison output from the comparison circuit 4 of the level detection circuit described above. Each RF signal taken into the AND gate 6 and tracking When the comparison output of the error signal and the focus error signal is lower than the reference value 5, the dirt detection signal indicating the dirt of the objective lens is output. However, although the AND of three signals is taken in this example, the present invention is not limited to this, and the stain detection may be performed based on any one signal.

FIG. 6 shows a warning method when the dirt of the objective lens is detected.
When a dirt detection signal indicating dirt on the objective lens is output from, the "CLEAN" character is displayed on the display provided on the player body, or the same is displayed on the display, as shown in FIG. By displaying the cleaning lamp shown in FIG. (B), turning on the cleaning lamp provided in the player main body, or issuing a warning by voice output, the dirt of the objective lens can be recognized. By cleaning the objective lens in accordance with the warning, it is possible to remove dust and the like adhering to the objective lens before sound skipping or malfunction occurs.

Next, the stain determination method based on the above various detection signal levels will be described with reference to FIG.

First, after the disk loading is completed, the optical pickup is driven to irradiate the recording surface of the disk with laser light, and the objective lens is driven in the focusing direction (steps 701 to 703).

In this state, the focus error level is first detected based on the detection signal obtained from the photodetector, and the comparison result with the reference value is output (step 704).
705). Next, the tracking error level is detected with the focus in, and the result of comparison with the reference value is output (steps 707 and 708). Further, after detecting the RF signal level in the focus-in and tracking-closed states, the comparison result with the reference value is output (steps 710, 711).

When a comparison output of these focus error signal, tracking error signal and RF signal is obtained,
In step 712, the dirt of the objective lens is determined, and if the levels of all the signals are below the reference value, it is determined that the objective lens is dirty. However,
As described above with reference to FIG. 5, even if the level of any one of the signals is lower than the reference value, it is possible to determine the dirt of the objective lens.

In this flowchart, the case where the dirt determination of the objective lens is performed based on the detection signals of the focus error signal, the tracking error signal and the RF signal has been described, but the present invention is not limited to this example, and the broken line of the flowchart is used. Focus servo loop gain detection and tracking servo loop gain detection (714,
715), the objective lens dirt determination may be performed. In this case, since the detection routine is reduced, the determination time is shortened.

FIG. 8 is a block diagram of a servo system including the above-mentioned actuator vibrating means.

That is, the photo detector (gain G
5) The detection signal detected by 20 is amplified to a predetermined level by a preamplifier (gain G0) 21, and the gain is adjusted by a variable gain section (gain G1) 22 for adjusting the servo gain inside the LSI 29A as the lens dirt detecting means. After that, when it is taken into the adder 23 via the switch SW for turning on / off the circuit of the servo system and added with the oscillation output s from the oscillator 24, an equalizer amplifier (gain G2) for phase compensation After being phase-compensated by 25, it is given to a drive circuit (gain G3) 26 as an objective lens vibrating means, and an actuator (sensitivity G4) 27 is driven by this drive circuit 26 to drive an objective lens 28. .

Here, the amount x of movement of the actuator 27 when the servo system is closed and when it is opened is

[Equation 1]

However, G _op is an open loop gain, and if the frequency is G _op >> 1, then x = s / G0.G1.G5. When open: x = s.G2.G3.G4.

FIG. 9 shows the relationship between the drive voltage of the actuator 27 and the frequency.

X which is the transfer function of the actuator 27
(S) / V (s) is

[Equation 2] Is. Here, m: mass D: viscosity coefficient K: spring constant B: magnetic flux density l: total coil length R: coil resistance.

Further, W0 = 2πf0 = √ (K / m) ξ = D / 2√ (Km).

That is, with respect to the sensitivity above the resonance frequency f0, since the acceleration is constant, if the sensitivity of the actuator 27 above the resonance frequency f0 is A [m / s ² / V], for example, 0.4 [m / s s ² ] The required voltage is 0.
It becomes 4 / A.

Further, the voltage required to bring the amplitude of 1 [μm] varies depending on the frequency f, and V = 1 × 10 ⁻⁶ ×
(2πf) ² / A.

Therefore, 0.4 / A = 1 × 10 ^-6 ×
When the frequency f is (2πf) ² / A, that is, f
It drives at 0.4 / A or more at a frequency of ≈101 [Hz] or less, and 1 × 1 at a frequency of f≈101 [Hz] or more.
It may be driven at 0 ⁻⁶ × (2πf) ² / A or more. However,
The frequency f is a frequency equal to or higher than the resonance frequency f0.

When the actuator is driven at a frequency f equal to or lower than the resonance frequency f0, and the actuator sensitivity equal to or lower than the resonance frequency f0 is B [m / V], the required drive voltage is V =
It is 0.4 / (2πf) ² / B. Here, 0.4 [m
/ S ² ] is considered to be the minimum required vibration in the tracking direction when a CD is taken as an example. This is because it is the acceleration of the disk specified in the Red Book, and it requires more vibration than the vibration generated in normal play.

FIG. 10 shows an example of a gain detection circuit having an automatic gain control function.
The same parts as those in FIG.

That is, L as the lens stain detecting means
The output of the variable gain unit 22 inside the SI 29B has a predetermined band component extracted by a bandpass filter (BPF) 30 at a point x, and an absolute value is taken by an absolute value circuit 31 and then a lowpass filter (LPF) 32. The low frequency component is extracted by and is taken into the microcomputer 29.

The addition output of the adder 23 has a predetermined band component extracted by a bandpass filter (BPF) 33 at a point y and an absolute value is taken by an absolute value circuit 34, and then a lowpass filter (LPF). ) 35, the low-frequency component is extracted and taken into the microcomputer 29.

Here, each band pass filter (BPF)
11, the signal waveforms passing through the absolute value circuits 31, 34 and the low pass filters (LPF) 32, 35 are shown in FIG.
As shown in.

That is, when a signal in which the oscillation output (disturbance signal) from the oscillator 24 is superimposed on the sine wave indicated by is output at points x and y, the signals output at these points x and y are banded. Pass filter (BPF) 30,
When the disturbance signal is removed by 33, the sine wave is represented by, and when the absolute value is taken by the absolute value circuits 31 and 34, the negative side of the signal is inverted to the positive side to obtain the signal indicated by, and the low-pass filter (LPF) A signal indicated by is set to have amplitudes α and β by 32 and 35.

In the gain detection circuit having such a configuration, the LSI 29 is instructed by the command from the microcomputer 29 in a state where both focusing and tracking are closed.
When the oscillator 24 in B is set (frequency = f, level = L) and turned on, a signal in which the disturbance signal is superimposed on the sine wave indicated by points x and y is output. The signal output to the points x and y is a bandpass filter (BPF) 3
When the disturbance signal is removed by 0, 33 to obtain a sine wave, and when the absolute value is obtained by the absolute value circuits 31, 34, the negative side of the signal is inverted to the positive side to obtain the signal indicated by, and the low-pass filter ( The LPF) 32, 35 outputs a signal whose amplitude is set to α, β.

Here, at the frequency f of the oscillator in the LSI 29B set by a command from the microcomputer 29, x = GOPy, where GOP is the open loop gain of the servo system and GOP = G0.G1.G2.G3 G4 and G5, so α = GOPβ.

Therefore, by knowing α and β, the current GOP (fHZ) can be known, and since the typical value of GOP is set at the design stage, how many dB deviates from the typical value of the current GOP. From the fact that
The dirt of the objective lens can be detected by detecting the dB deviation of a predetermined level.

According to the above-described gain detection, the drive circuit (gain G3) 26 drives the actuator (sensitivity G4) 27, and the objective lens 28 is driven in the tracking direction, the focusing direction, or the two simultaneous directions. It is possible to remove dust and the like adhering to the lens 28.

That is, FIG. 12 shows a plastic objective lens 28 held by a holder 41, which is one of the constituent members of the actuator 27, and as described above with respect to such an actuator 27, For example, when vibrating in the tracking direction, f≈101
At frequencies below HZ, drive at 0.4 / A or higher, and f≈
1 × 10 ⁻⁶ × (2πf) at frequencies above 101Hz
By driving at ² / A or more, the objective lens 28 is vibrated in the tracking direction, and the dust 40 or the like adhering to the lens surface of the objective lens 28 is formed on the outer peripheral edge of the objective lens 28 by the protrusion 28a. Scattered to the side.

As a result, dust on the effective diameter on the lens surface of the objective lens 28 is removed, so that the deterioration of the level of the reading light which is the reflected light from the disk is prevented before sound skipping or malfunction occurs. .

Further, as shown in FIG. 13, in the case of the objective lens 28 made of glass, the surface is made substantially flat, so that when the above-mentioned drive signal is supplied to the actuator 27, a predetermined value is obtained. Due to the vibration, dust 40 and the like are scattered outside the effective diameter of the objective lens 28.

As described above, in this embodiment, the dirt of the objective lens 28 is detected by the LSIs 29A and 29B as the lens dirt detecting means based on the reflected light from the disc passing through the objective lens 28 of the optical pickup, and the objective lens is detected. The drive circuit 26 as a vibrating means vibrates the objective lens 28 with a predetermined drive signal to shake off dust and the like adhering to the lens surface.

Therefore, the objective lens 28 can be oscillated in small increments, for example, in the tracking direction by a predetermined drive signal without changing the existing configuration.
Since the dust 40 and the like adhering to 8 can be shaken off,
With a simple structure, it is possible to remove dust and the like adhering to the objective lens before sound skips and malfunctions occur.

[0054]

As described above, according to the disc player of the present invention, the dirt on the objective lens is detected by the lens dirt detecting means based on the reflected light from the disk passing through the objective lens of the optical pickup. Then, the objective lens vibrating means vibrates the objective lens, so that dust and the like adhering to the lens surface are shaken off.

Therefore, the objective lens can be oscillated in a small amount in the tracking direction by a predetermined drive signal without changing the existing configuration, and dust and the like adhering to the objective lens can be shaken off. It is possible to remove dust and the like adhering to the lens before sound skips and malfunctions occur.

[Brief description of drawings]

FIG. 1 is a diagram showing a level detection circuit for explaining a dirt detection method according to an embodiment of a disc player of the present invention.

FIG. 2 is an RF passing through each part of the level detection circuit of FIG.
It is a figure for demonstrating the waveform of a signal.

FIG. 3 is a diagram for explaining a waveform of a tracking error signal passing through each part of the level detection circuit of FIG.

FIG. 4 is a diagram for explaining a waveform of a focusing error signal that passes through each part of the level detection circuit of FIG.

5 is a diagram showing a dirt detection circuit for detecting dirt of the objective lens from the level of each signal detected by the level detection circuit of FIG.

FIG. 6 is a diagram showing a warning method when stain detection is performed by the stain detection circuit of FIG.

FIG. 7 is a flow chart for explaining the level detection circuit of FIGS. 1 and 5 and the level detection of each signal by the level detection circuit.

FIG. 8 is a block diagram of a servo system including a vibration unit of an actuator.

9 is a diagram showing a relationship between a drive voltage and a frequency of the actuator shown in FIG.

FIG. 10 is a diagram showing a gain detection circuit having an automatic gain control function.

11 is a diagram showing a waveform that has passed through a predetermined portion in the gain detection circuit of FIG.

FIG. 12 is a cross-sectional view showing a plastic objective lens.

FIG. 13 is a diagram showing an objective lens made of glass.

[Explanation of symbols]

 1 peak hold circuit 2 bottom hold circuit 3 arithmetic circuit 4 comparison circuit 5 reference value 20 photodetector 21 preamplifier 22 variable gain section 23 adder 24 oscillator 25 equalizer amplifier 26 drive circuit 27 actuator 28 objective lens 29 microcomputer 29A, 29B LSI 30, 33 band pass filter 31,34 absolute value circuit 32,35 low pass filter

Claims (1)

[Claims] 1. A disc player including an optical pickup, a lens stain detecting unit for detecting stains on the objective lens based on reflected light from a disc passing through an objective lens of the optical pickup, and the lens stain. An objective lens vibrating means for vibrating the objective lens based on the detection result of the detecting means.