JPS61276185A - Head shifting device - Google Patents

Abstract

PURPOSE:To obtain a head shifting device having a small time of long distance seeking against the variance of the track pitch between media or the scale of the head shifting device by using a correctable correction table. CONSTITUTION:A track error detector is divided into parts 9a and 9b and the output difference between both parts 9a and 9b is corrected via an operational amplifier 10 and a filter 11. Thus an error signal 18 is obtained. this signal 18 is supplied to a track actuator 16 and the laser light is made to follow a specific track. While a CPU 32 switches a switch 14 in a long distance seek mode and sets a shift degree sent from a position sensor 28 to a counter 29. The the CPU 32 gives the data sent from a ROM 30 to a voice coil motor 27 via a D/A converter 31. Thus a high-speed seeking action is attained. Here the CPU 32 shifts the contents of a ROM 34 to a RAM 33 when a head shifting device is started for use of a correction table. Then the degree of said shift is added to the value of the correction table in response to the need for the long distance seek. Thus the correction value on the RAM 33 is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head moving device, and more particularly to a moving device for a read/write head of an information processing device that reads and writes information to a disc-shaped medium.

[Conventional technology]

Conventionally, this type of information recording and reproducing apparatus has two types of modes for moving a head for reading and writing information.

The first mode is used when moving over short distances, and involves moving the head one track at a time.

The second mode is used when moving long distances, and the positioner with the head on it is moved at high speed near the target track using the sensor attached to the positioner, and then the first mode is used. mode, and move to the target track while checking the track. - In this second mode, the movement is performed using sensors, so the amount of movement is calculated, but the distance between the sensors is the same as the distance between the tracks. In many cases, it is not an integer multiple. Therefore, when calculating the amount of movement in the second mode, simple division is not sufficient, and correction is performed after division.

[Problems to be solved by the invention] In conventional devices, the user had to have their own table for correcting the amount of movement, but this correction table was fixed. This caused variations between media and devices. Therefore, it was not necessarily an optimal correction table. In particular, when the specifications of the medium change and the track spacing changes, it cannot be accommodated at all, and it takes more time than necessary to move the head.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head moving device for a disk-type information processing apparatus that eliminates the disadvantage that a correction table becomes non-optimal due to changes or variations in the medium or device included in the head moving device.

[Means for solving problems]

The head moving device of the present invention includes a head for reading and writing information, a track error detector for detecting deviation of the head from the track, an operational amplifier for amplifying the output of the track error detector, and an operational amplifier for amplifying the output of the operational amplifier. A filter for correction, a processing device for managing each operation, a jump pulse generation circuit that is controlled by the processing device and generates a waveform for jumping the head, and an output from the filter and an output from the jump pulse generation circuit. a switch that turns off and on under the control of the processing device; a switch that turns the signal from the switch 0N10FF under the control of the processing device;
a current amplifier that changes the current applied to the output from the switch; a track actuator that moves the head in the track direction using the output of the current amplifier; a filter that corrects the output from the filter; and a positioner that moves the head by a large amount. , a sensor that detects the movement of the positioner and generates pulses, a counter that counts the pulses of the sensor, a ROM that changes output data depending on the value of the counter, and a digital sensor that converts the output of the ROM into an analog signal. - an analog converter, a switch that is controlled by the processing device to switch between the output of the second filter and the output of the digital-to-analog converter, a current amplifier that changes the current according to a signal switched by the switch, and the The apparatus is characterized by comprising a voice coil motor that moves the positioner of the head by the output current of a current amplifier, and a memory that can be written to, read from, and read by the processing unit.

〔Example〕

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

Although the present invention can be used in an information recording/reproducing apparatus using any disk-shaped medium such as a magnetic disk, a floppy disk, or an optical disk, this embodiment shows an embodiment adapted to an optical disk.

FIG. 2 is a conceptual diagram of an optical disk head according to an embodiment of the present invention. Laser light A emitted from a laser diode 2 (hereinafter abbreviated as LD) is changed from elliptical polarization to circular polarization by a beam splitter 3, passes through a 1/4λ plate 4, and is focused onto a recording/reproducing medium 1 by a lens 5. tied together. The focused laser beam A is reflected by the medium 1, turned into parallel light by the lens 5, and returns to the beam splitter 3 through the 1/4λ plate 4. The beam splitter 3 is a half mirror. Then, the laser beam A that returns is sent to another beam splitter 6. The beam splitter 6 splits the laser beam A into two parts and sends one of them to the focus error detector 8.

In this embodiment, since the knife method is used for focus error detection, the knife 7 is placed in front of the focus error detector 8. The output of the focus error detector is sent to a focus servo circuit, which moves the lens 5 in the vertical direction so that the focus is on the medium 1.

The remaining laser light is sent to a track error detector 9. A groove is previously cut in the surface of the medium 1, and when the laser beam A deviates from the center of the groove, the direction of reflection of the reflected light 9 becomes oblique to the groove. Therefore, if the light reflected on the plane of the medium only is set at the center of the track error detector 9, if the laser beam A deviates from the center, the laser beam on the track error detector 9 will deviate from the center. This is shown in FIG. Figure 3(b) shows when the focus is on the center of the midsection, and (α
) and (c) respectively represent the time when it deviates from the groove. Therefore, if the track error detector 9 is divided into two parts 9α and 9b at the center as shown in FIG. A track error signal 18 as shown is produced. This fifth
As can be seen from the figure, this track error signal 18 becomes 0 only at the center of the medium surface, and from 0 as the center, movements to the right are positive and movements to the left are negative; By using this, it is possible to servo the laser beam A so that it is always at the center of the groove.

The circuit is realized by passing the track error signal 18 through the switches 12 and 14 to the current amplifier 15 in FIG. 4, and causing the current amplifier 15 to flow a current to the track actuator 16 that moves the lens 5 in the track direction. Ru. This allows the laser beam A to be directed into a specific groove (this is used for recording and reproducing information).

(hereinafter referred to as a track).

Next, short-distance truck movement will be explained.

If it becomes necessary to move from the current track to a nearby track, the processing unit 32 (see FIG. 8, hereinafter abbreviated as CPU) controls the operation of the optical disk device.
First, the servo/jump switching signal 19 is used to switch the switch 12. Then, the CPU 32 sends a forward signal 21 or a reverse signal 22 to the jump pulse generation circuit 13. When the jump pulse/pulse generating circuit 13 receives the forward signal 21 or the reverse signal 22, it generates a jump pulse 17. jump pulse 1
7 is made up of positive and negative pulses with a constant width, as shown in FIG.

Forward (α) and reverse (b) have opposite signs. In FIG. 4, the jump pulse 17 is applied to the current amplifier 15 via the switches 12 and 14, and the current amplifier 15 applies a similar current to the track actuator 16, thereby moving the lens 5 by a certain amount. If you match it to the track pitch, you can perform track jumps. After the jump, CPU 32
is the servo/jump switching signal 19, switch 1
2 and activates the track servo to cause the laser beam A to follow the moved track. By repeating the above operation, a short distance seek is performed. However, if the lens 5 jumps many tracks or the eccentricity of the track is large, the lens 5 will be tilted towards the end of the movable range. On the other hand, the structure of the read/write head of an optical disk is such that the read/write head 36 is placed above the positioner 35 as shown in FIG. The positioner 35 is moved in the horizontal direction by the voice coil 27, and the movement is performed using a scale 37 fixed to the positioner 35, which is detected by the sensor 4 and generates a pulse. Therefore, if the positioner 35 is also moved using the track error signal 18, the positioner 35 will also move as the lens 5 moves, and the lens 5 can be positioned at the center of the movable range. This is due to the current amplifier 26 driving the voice coil motor 27 as shown in FIG.
Filter the track error signal 18 to the switch 25
This can be achieved by sending it through the . By adding this circuit, it is possible to jump several tracks when seeking by track jump, and it is less susceptible to the effects of eccentricity.

This allows for seeking, but as the number of tracks to be moved increases, the moving time becomes longer. Therefore, this mode, which has a long-distance seek mode in which the vehicle moves at high speed to near the target track, will be described. This will be explained with reference to FIG. When the CPU 32 needs to perform a long-distance seek, it activates the track servo 0N10FF.
Signal 20 turns off switch 14 (see FIG. 4), deactivating the track servo loop. Then the CPU
32 switches the switch 5 according to the positioner mode switching signal. Then, the amount of movement of the positioner 35 is set in the counter 29. Then, according to the value of counter 29! Digital data is sent from the +ROM 30 to a digital-to-analog converter (hereinafter referred to as D/A) 31. The D/A 31 converts the data in the ROM 30 into an analog signal, and the analog signal is sent to the current amplifier via the switch section, and the current amplifier 26 changes the current flowing to the voice coil motor 27 based on the analog signal. When the voice coil motor 27 operates, the positioner 35 (
When the scale 37 (see FIG. 7) moves and the positioner 35 moves, the scale 37 (see FIG. 7) also moves, and this movement causes the sensor 4 to generate a pulse. The counter 29 counts down due to the pulse from this sensor attack, and R
The data from the OM 30 also changes, and the current flowing to the voice coil motor 27 also changes, and this continues until the counter 4 reaches 10''.Counter 29
When the value becomes '0'', the CPU 32 returns the switch 5 to its original state due to the positioner mode switching signal being dead, and causes the track servo loop to also operate based on the track servo 0N10FF signal 20.Then, the track value at that time is Check the current track value, if it is still far away, move to long distance seek mode again, and if it is close, repeat track jump which is short distance seek mode, repeating 0 or more until the target track is reached. Perform distance seek.

In this long-distance seek, a large voice coil motor n is used, so high-speed seek can be achieved. However, due to the high speed, the pitch of the sensor 4 is larger than the track pitch of the medium 1. Therefore, when performing a long distance seek, the CPU 32 must calculate the value to be set in the counter 29. This can be calculated by dividing the number of tracks to the target track by the number of tracks per pitch of sensor 4, but in many cases the pitch of sensor 28 is not an integral multiple of the track pitch, so simply dividing will result in a deviation. There will be parts that will get bigger. Therefore, we have a table of correction values and simply divide the result and then add or subtract the correction value to the result to reduce the deviation.

However, this table of correction values has conventionally been fixed.

Therefore, due to variations in the track pitch of the medium and variations in the sensor 4 and the scale 37, the value may deviate from the optimum value. In particular, when the track pitch of the medium changes, it cannot be dealt with at all, and correction may even lead to worse results.

A countermeasure against this problem is an object of the present invention, and a circuit diagram of a first embodiment thereof is shown in FIG. In FIG. 1, ROM 34 is a conventional fixed correction table. In addition, in the example of FIG. 1, there is a RAM 33 that can be read and written. First, C
PU 32 is activated when the device starts operating (e.g.
R-ON (7) J: Unatoki), ROM 34 O
After moving all the contents to RAM 33 and using the value of RAM 33 as a correction table from now on, and performing a long distance seek, if a long distance seek is still required, add the amount of movement to the value of the correction table, and Save the value to RAM 3
Write it as the correction data above. If you have gone too far during a long distance seek, subtract the amount that went too far and correct the correction data.By sequentially correcting the long distance seek correction values in this way, you can create an optimal correction table and change the medium. Also, even if there are scale variations between devices, optimal long-distance seek can be performed.The block diagram of the circuit of the second embodiment is shown in Figure 8.
The difference from the diagram is that ROM 34 and RAM 33 are missing.
This is because 38 non-volatile RAMs have been added. In the first embodiment, the values in the RAM 33 containing the correction table disappear once the power is turned off, and the correction table is corrected again after being turned on again. For this reason, the correction table was not always appropriate for a while after the power was turned on. The second embodiment improves on this point, and by making the correction table RAM 38 non-volatile, the previous correction table is retained even when the power is turned off, and even after the power is turned on again. Even the correction table remains optimal. The rewriting of the correction table has also been improved. 1st
In this embodiment, if there was a long-distance seek offset, the values in the correction table were immediately changed. However, with this, the track pitch differs depending on the location even on the same medium, so if you happen to seek at a location where the deviation is large, the correction value will not be appropriate at the next seek. Therefore, when a long distance seek is still required after a long distance seek, half of the remaining seek amount is added instead of adding the remaining value as is. Then, leave the decimal point of the correction value used as a result (
However, when setting a value in the counter 29, it is cut off. ). By doing this, the influence of some areas with large deviations can be reduced. The operation flow is shown in FIG. 9 (α) and (b). In this FIG. 9, the decimal point is 0. The reason for rounding down when the value is smaller than 25 and rounding it up when it is larger than 0.75 is to speed up the convergence of the correction value. According to this embodiment, it is possible to realize a head moving device that is not susceptible to variations in track pitch within one medium and has an optimal correction table even when track pitch between media changes. [Effect of the Invention] As explained above. By having a correction table that can be modified, the present invention can have an optimal long-distance seek correction table even if there are variations in track pitch between media, changes in track pitch, variations in device scale, etc. This has the effect of making it possible to create a disc-shaped information recording device with short long and short distance seek times.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a control circuit of a positioner showing a first embodiment of the present invention, Fig. 2 is a conceptual diagram of a head in the embodiment of the present invention, and Fig. 3 (α), (b), (C ) is a diagram showing the relationship between the position of the track error detector and the laser beam when the track is off, Figure 4 is a block diagram of the track servo system circuit, and Figure 5 is the position of the laser beam on the medium surface. Figures 6 (α) and (b) are waveform diagrams of pulses for track jump, Figure 7 is a conceptual diagram of the positioner, and Figure 8 is the positioner of the second embodiment. The block diagram of the control circuit of FIG. 9(α) and FIG. 9(b) are flowcharts when changing the correction table in the second embodiment.

Claims (1)

[Claims] (1) A head that reads and writes information, a track error detector that detects the deviation of the head from the track, an operational amplifier that amplifies the output of the track error detector, and a filter that corrects the output of the operational amplifier. , a processing device that manages each operation, a jump pulse generation circuit that is controlled by the processing device and creates a jump waveform for the head, and an output from the filter and an output from the jump pulse generation circuit that is controlled by the processing device. a switch whose switching is controlled; a switch which turns ON/OFF a signal from the switch under control of the processing device; a current amplifier which changes the current according to the output from the ON/OFF switch; a track actuator that moves the head in a track direction; a filter that corrects an output from the filter; a positioner that moves the head a large amount; and a sensor that detects movement of the positioner and generates a pulse;
a counter that counts pulses of the sensor; a ROM that changes output data according to the value of the counter; a digital-to-analog converter that converts the output of the ROM into an analog signal; and a second filter that is controlled by the processing device. a switch for switching between the output of the converter and the output of the digital-to-analog converter; a current amplifier that changes the current according to a signal switched by the switch; and a voice coil motor that moves the positioner of the head using the output current of the current amplifier. A head moving device comprising a memory that can be written to and read by the processing device.