JPS6161239A - Quakeproof preventing device of optical information reading device - Google Patents

Abstract

PURPOSE:To eliminate malfunction due to flows of a disk and to eliminate the need for turning off and on of a vibration detecting device according to the state of the disk by providing the vibration detecting device at the outside of a track servo loop and changing over characteristics of a servo device by the detection signal. CONSTITUTION:Outputs of a pressure sensor 12 for detecting vibration such as external shock, etc. are sent to an amplifier 13, and after amplification, the output 13a is sent to a level judging circuit 5, and outputs of the level judging circuit 5 are sent to an amplifier 4. Other constitution is the same with conventional one. When shock TS is given from the outside, it is detected by the pressure sensor 12, and the output is amplified by the amplifier 13 and sent to the level judging circuit 5. The level judging circuit 5 detects vibration which is out of the range of + or -V2, and at this time, a gain of the amplifier 4 in the servo loop is raised. Even if flows are on the disk, malfunction is not caused because changeover of the gain is off from the loop.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a means for detecting pressure in order to improve the anti-vibration characteristics of a compact disc brake, and a system that switches the characteristics of the servo system depending on the signal level. The present invention relates to an anti-seismic device for an optical information reading device.

[Conventional technology]

FIG. 4 is a system block diagram of a conventional anti-earthquake prevention device for an optical information reading device. In this figure 4, 1 and 2
is a photodetector for detecting secondary light of laser light. The outputs of photodetectors 1 and 2 are applied to a non-inverting input terminal and an inverting input terminal of a converter 3, respectively.

The converter 3 is for converting the photocurrent output difference between the photodetectors 1 and 2 into a voltage difference, and its output 3a is amplified by the amplifier 4, and the output 3a is used as a level judgment image.
! The level is determined in step 215 and output to the amplifier 4.

The output of the amplifier 4 is sent to a phase compensation circuit 6, and the output of the phase compensation circuit 6 is sent to a current amplifier 7. The tracking actuator 8 is driven by the output of the current amplifier 7.

The tracking actuator 8 has a built-in tracking mirror that swings the laser beam so that the laser beam follows the pits in which information is written.

A laser beam from a laser diode 9 is incident on the tracking actuator 8 , and the laser beam is reflected by a tracking mirror and enters a laser beam splitter 10 .

The laser beam splitter IO splits this laser light and irradiates it onto the disk 11, and also onto the photodetectors 1 and 2.

Next, the operation will be explained. In FIG. 5, the disk 11
It shows the pit into which the above information has been drilled, and the one-dimensional and two-dimensional states of the laser beam. lla is pit, llb is 1
The secondary light, llc, and lid are secondary lights. Whether the primary light 11b is tracking on the bit 11a is detected using the two-dimensional 11c and lid.

FIG. 6 is for explaining the method of detecting the error signal. Photodetector 1 is a photodiode for detecting the secondary light ie shown in FIG. 5, photodetector 2 is a photodiode for detecting the two-dimensional lid shown in FIG. 5, and 3 is a differential sensor for obtaining a tracking error signal. The amplifier is converter 3 in FIG.

Track deviation is detected by utilizing the fact that the laser spot within the pit Ila does not return to the respective photodetectors 1 and 2 due to diffused reflection.

In Figure 6, the level at the inverting input end (-input end) of the converter 30 is higher, so the output 3a is a negative value, and this is amplified by the amplifier 4 to move the laser spot a little to the left. If you shift it, the servo will work.

In FIG. 4, the tracking error signal, i.e., the output 3a of the converter 3, is voltage amplified by an amplifier 4, compensated for around the phase of the tracking actuator 80 by a phase compensation circuit 6, and current amplified by a current amplifier 7, The actuator 8 operates an internal tracking mirror to shift the position of the western laser spot on the disk 11.

In such a servo system of an earthquake prevention device for an optical information reading device, when the track servo comes off due to external vibration, the conversion ability 3 as a track iJ4 difference signal is
The output 3a of becomes large. The situation is shown in FIG. This TS in FIG. 7 is an external shock, and the level judgment circuit 5 shows that the tracking error signal is ±V! By detecting that it is outside the range and increasing the gain of the amplifier 4 based on the detection signal, off-track can be prevented.

[Problem that the invention seeks to solve]

However, as shown in Figure 7, the reason why the trunk error signal is so large is that in addition to external shocks, the same error signal outside the ±V range is also generated when there are scratches, fingerprints, dust, etc. on the disc itself. . In this case, there will be no pits, so increasing the gain may actually increase the number of off-tracks.If a disc with many scratches etc. is to be played again, the level judgment circuit 5 I was trying to make it not work.

In addition, in the case of Fig. 4, since the tracking actuator 8 itself to be controlled is used as a vibration sensor from the outside, by the time vibration is detected, the track has already come off, and the gain is increased. There were times when I couldn't make it in time even if I turned it up.

Since the earthquake prevention device of conventional optical information reading devices is configured as described above, if there is a scratch on the disk, it is more likely to go off track, and it is necessary to disable the device depending on the condition of the disk. It had some disadvantages, such as being rusty and making it difficult for the country to use it for practical purposes.

This invention was made to solve these problems, and is an anti-earthquake prevention device for optical information reading devices that eliminates the movement of the pieces due to scratches on the disk, and provides more reliable seismic performance. : The purpose is to obtain.

[Means for solving problems]

The seismic prevention device for an optical information reading device according to the present invention includes an electromagnetic actuator that causes light irradiated onto an information surface to wave on the information surface, and an electric energy applied to the electromagnetic actuator that causes the light to be directed along one information groove. The vibration detecting means is installed outside the servo loop of the servo means, detects vibrations, and switches the servo characteristics of the servo means in accordance with the detected output.

[Effect]

In this invention, the '#1im optical actuator causes the nine irradiated on the front information surface to wave, and the servo means traces this light onto one information groove, and when there is vibration such as an external shock, the vibration detection means The characteristics of the servo means are switched based on the detection.

〔Example〕

Hereinafter, embodiments of the seismic prevention device for the optical information reading device of the present invention will be explained based on the drawings! 152 BA. FIG. 1 is a block diagram showing the configuration of one embodiment. This first
In the figure, for the sake of clarity, parts that are the same as those in FIG. 4 are given the same reference numerals, and their explanations are omitted, and the parts that are different from those in FIG. 4 will be mainly described.

As is clear from comparing Figure 1 with Figure 4,
In the figure, the parts indicated by numerals 1 to 11 are the same as in Fig. 5.
The parts after the reference numeral 12 are different from those in FIG. 4 and are the parts that are characteristic of the embodiment shown in FIG.

That is, 12 is a pressure sensor for detecting vibrations such as external shocks. The output of this pressure sensor 12 is sent to an amplifier 13, where it is amplified, and then the output 13a is sent to the level determination circuit 5. The output of this level determination circuit 5 is sent to an amplifier 4. The other configurations are the same as in FIG. 4.

Next, the operation of the vibration prevention device for the optical information reading device of the present invention configured as above will be explained.

The servo operation during normal operation is the same as that shown in FIG. 4, so its description will be omitted. Now, as shown in Fig. 2, when an external shock TS is applied, the pressure sensor 12 detects it and
The output is amplified by an amplifier 13 and input to a level determination circuit 5.

The level determination circuit 5 detects vibrations outside the range of ±v2, and increases the gain of the amplifier 4 in the servo loose at that time. Even if there is a scratch on the disc, the gain switching is out of the loop, so it will not malfunction.

In the above embodiment, the gain of the amplifier 4 in the servo loop is switched by the output of the level determination circuit 5, but the frequency characteristics of the amplifier 4 may be switched depending on the vibration frequency.

FIG. 3 is a block diagram showing the configuration of a second embodiment of the invention. In the case of FIG. 4, an optical pickup 14 and a damper 15 for supporting it are provided in the configuration of the embodiment of FIG. 1.

The optical pickup 14 includes a photodetector 1.2, a tracking actuator 8, a laser diode 9, and a beam splitter 10.

The other configurations are the same as in FIG. 1.

With this configuration, the servo operation during normal operation is the same as that shown in FIG. 4, so a description thereof will be omitted.

Now, as shown in Figure 2, the external shock T
When S is applied, the pressure sensor 122>; first detects it, its output is amplified by the amplifier 13, and the output 13
a enters the level determination circuit 5. Level judgment circuit 5 is
2 is detected, and at that time the key or frequency characteristic of the amplifier 4 in the servo loop is switched.

Since the optical pickup 14 is supported by the bumper 15, external shocks are transmitted with a delay. Therefore, when the optical pickup 14 starts to move due to vibrations, the servo characteristics have been switched to make it more resistant to vibrations, so the vibrations will not cause it to go off track.

In the case of this second embodiment, especially when the seismic force reaches the mechanical part (not shown) that causes the displacement of the servo, the seismic characteristics of the servo have been improved, and more reliable seismic performance can be obtained. effective.

In the embodiment shown in FIG. 3, the optical pickup 14 is supported by the damper 15, but if the vibration is transmitted to the pressure sensor 12 and the original pickup 14, other supports may be used. It goes without saying that there may be propagation delay devices on the device or elsewhere.

〔Effect of the invention〕

As explained above, this invention is configured such that the vibration detection means is provided outside the loop of the tracker and the characteristics of the servo means are switched based on the detection signal, thereby eliminating malfunctions caused by scratches on the disk, etc. In addition, there is no need to turn off or turn on the vibration detection device depending on the state of the disk, and there is an effect that stable and problem-free seismic performance can be obtained in actual use.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the earthquake prevention device for an optical information reading device of the present invention, and FIG. 2 is a diagram for explaining the operation of the earthquake prevention device for the optical information reading device. FIG. 3 is a block diagram showing the configuration of another embodiment of the earthquake prevention device for an optical information reading device according to the present invention, and FIG. 4 is a block diagram of a conventional earthquake prevention device for an optical information reading device.
Figure 5 is a diagram to explain the relationship between the information groove on the disk and the light spot in the earthquake protection device of the optical information reading device shown in Figure 4, and Figure 6 is the earthquake resistance of the optical information reading device shown in Figure 4. FIG. 7 is a diagram illustrating a method of detecting a failure error signal by the prevention device, and is a diagram for explaining the operation of the earthquake prevention device of the optical information reading device shown in FIG. 4. 1.2...Photodetector, 3...Converter, 4゜13...Amplifier, 5...Level judgment circuit, 6...
Phase compensation circuit, 7... Current amplifier, 8... Tracking actuator, 9... Laser diode, 10
...beam splitter, 11...disk, 12.
...Pressure sensor. Note that the same reference numerals in the figures indicate the same or similar parts. Agent Masuo Oiwa Figure 4 Figure 5 Figure 6 Procedure amendment (voluntary) Showa year, month, day

Claims (2)

[Claims] (1) An electromagnetic actuator that causes the light irradiated onto the information surface to wave on the information surface, and a servo means that controls the light to be traced along one information groove by electric energy applied to this electromagnetic actuator. Earthquake protection for an optical information reading device, characterized in that it is equipped with vibration detection means provided outside the servo loop of the servo means, which detects vibrations and switches the servo characteristics of the servo means according to the detected output. Device. (2) The seismic prevention device for an optical information reading device according to claim 1, characterized in that the sensor section of the vibration detection means is provided at a part of the optical information reading device where vibrations are transmitted fastest.