JPH0519782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording/reproducing apparatus using a recording medium such as a magnetic disk or an optical disk having a plurality of tracks for recording information.

[Conventional technology]

In an information recording and reproducing device that records and reproduces information on a recording medium having a plurality of information storage tracks such as a magnetic disk or an optical disk, in order to improve the reliability of the information reproduction signal, there is a reproduction circuit for improving the reliability of the information reproduction signal. Some of them use transversal filters.

In the conventional transversal filter of this type of information recording/reproducing device, the constant of the attenuator that determines its output characteristics is constant, and its value is adjusted to its optimum value in response to variations in the characteristics of the recording medium and recording/reproducing head. It is impossible to select a suitable value.

FIG. 3 is a circuit diagram showing an example of a conventional information recording and reproducing apparatus as described above, and illustrates a reproducing circuit of a magnetic disk device.

As shown in the figure, the read signal read out from the magnetic disk 18 by the magnetic head 2 is amplified by the amplifier 3 and input to the transversal filter 17. The transversal filter 17 includes a delay device 4, an attenuator 15, and a subtracter 6, and the output signal from the amplifier 3 is branched and inputted to the delay device 4 and the attenuator 15. The signal input to the delay device 4 is input to the subtracter 6 as an output signal with a certain time delay, while the output signal of the amplifier 3 and the reflected signal from the delay device 4 are input to the attenuator 15. The amplitude of these signals is attenuated by a constant attenuation ratio K (for example, K=0.2) and the subtractor 6
is input. The subtracter 6 subtracts these signals and outputs the signal as the output signal of the transversal filter 17, and the output signal of the transversal filter 17 is digitized by the demodulator 8 and sent as a reproduction signal via the terminal 10. Sent to upper circuit. At this time, the attenuation ratio K of the attenuator 15 is constant, and in order to set this value, a value that provides the best reliability on average is simulated, taking into account variations in the recording medium and recording/reproducing head. The method used is to find and set the value by . However, there are considerable variations in the characteristic values of the magnetic disk 18 and the magnetic head 2, and in particular, magnetic disks have different recording densities and relative speeds between the recording medium and the recording/reproducing head between their inner tracks and outer tracks. Since there is a large difference in the readout signals, there is a problem in that the above-mentioned means cannot necessarily obtain an output signal with sufficient characteristics. Therefore, the conventional information recording and reproducing apparatus having a transversal filter has the disadvantage that the reliability of the reproduced signal, that is, the frequency of occurrence of read errors is still insufficient.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention, in other words, the purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional information recording and reproducing apparatus using a transversal filter in the reproducing circuit, and to improve the characteristic constant of the transversal filter. By making it variable, it is possible to obtain an output that corresponds to variations in the characteristics of the recording medium and the recording/reproducing head, thereby improving the characteristic values of the reproduced signal and producing highly reliable information with fewer read errors. The purpose of the present invention is to provide a recording/playback device.

[Means for solving problems]

The information recording/reproducing apparatus of the present invention includes: a recording/reproducing head for recording or reproducing information on a recording medium; an amplifier for inputting and amplifying a read signal read out from the storage medium by the recording/reproducing head; a transversal filter which inputs an output signal of the amplifier and a signal representing a specific constant and outputs an output signal obtained by converting the output signal of the amplifier by the specific constant; and inputs the output signal of the transversal filter. a demodulator that demodulates this into a binary data signal and sends it out; and when the read/write control signal is in a write state, the output signal of the demodulator and the memory address signal are inputted and included in the output signal of the demodulator. Data information is stored as the specific constant at the address specified by the memory address signal, and when the read/write control signal is in a read state, a memory address signal is input from the host device and the address specified by this is stored. and a memory for outputting the stored specific constant to the transversal filter, the transversal filter inputting the output signal of the amplifier and giving it a certain delay time. inputting a delay device to output, an output signal of the amplifier, a reflected signal from the delay device, and the specific constant from the memory, and converting the output signal of the amplifier and the reflected signal from the delay device into the specific constant; a variable attenuator that outputs an attenuated signal attenuated by a specified attenuation rate; and a variable attenuator that inputs the output signal of the delay device and the attenuated signal and outputs a signal obtained by subtracting them as an output signal of the transversal filter. and a subtractor for subtracting the data, and the storage medium is configured such that the data information corresponding to some or all of the tracks and the address of the recording/reproducing head is stored in advance on the specific track.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment in which the present invention is applied to a magnetic disk device. In FIG. 1, reference numeral 1 denotes a magnetic disk for storing information;
Reference numeral 2 is a magnetic head for recording and reproducing. The information stored on the magnetic disk is transferred to the magnetic head 2.
The readout signal 21 read out is amplified by the amplifier 3 and input to the transversal filter 7 as an amplifier output signal 22. The transversal filter 7 includes a delay device 4, a variable attenuator 5, and a subtracter 6, and its output, the transversal filter output signal 25, is input to a demodulator 8 and demodulated into binary data. The demodulated signal is output as a reproduced signal 26 to the upper circuit via the output terminal 10 and is also input to the memory 9 and the input terminal of the address discriminator 19. A read/write control signal 11 is input to the memory 9 from the upper circuit, and a memory address signal 12 or 14 is input from the upper circuit or the address discriminator, while the memory read signal 13 from the memory 9 is input to the variable attenuator 5. The amount of attenuation in the variable attenuator 5 changes depending on the value of the input data.

Next, the operation of the transversal filter 7 will be explained with reference to FIG.

The input waveform 30 is an example of the waveform of the amplifier output signal 22 input to the transversal filter 7. The delay device output signal 23 from the delay device 4 is output as a delayed waveform 31 delayed by the delay time T of the delay device 4. Since the output end of the delay device 4 is open terminated, the input waveform 30 is totally reflected and the amplifier output signal 2
The reflected waveform 32 is superimposed on the signal 2. Since the input terminal of the delay device 4 is configured to match the combined resistance of the output resistance of the amplifier 3 and the input resistance of the variable attenuator 5, no reflection occurs here. Therefore, when a signal having an input waveform 30 is input to the transversal filter 7, the input waveform 30 and the reflected waveform appear, and this combined waveform is input to the variable attenuator 5, and the attenuation amount (tap gain The variable attenuator output signal 24 having an attenuated waveform 33 is output to the subtracter 6. A delay device output signal 23 having a delayed waveform 31 and a variable attenuator output signal 24 having an attenuated waveform 33 are input to the subtracter 6, and these are subtracted and the transversal filter output signal 25, which is the output thereof, is obtained by subtracting them. A signal having the combined waveform 34 is output. The half width T _WO of the composite waveform 34 is the same as that of the delayed waveform 3.
Since the attenuation waveform 33 is subtracted from 1, the delayed waveform 3
It is smaller than the half width T _WI of 1. Therefore, the degree of influence caused by interference between adjacent waveforms is reduced, and signal quality can be improved, that is, read errors can be reduced. As the tap gain of the variable attenuator 5 is increased, the half width T _WO of the composite waveform 34 becomes smaller, but the undershoot (portion where the signal magnitude is negative) _VS becomes larger. Since this undershoot is also one of the causes of signal deterioration, it deteriorates the signal quality. Therefore, there is an optimal tap gain for the value of the half-width T _WI of the amplifier output signal 22 (same as the half-width of the delay device output signal 23), and that value is proportional to the magnitude of the half-width T _WI . Uniquely determined.

Next, the operation of the present invention will be explained with reference to FIG. 1 again.

During the manufacturing process of a magnetic disk drive, the waveform of the reproduced signal at each address (track address and head address) is inspected, and the variable attenuator 5 of the transversal filter 7 for each address adjusts the tap gain to optimize signal quality. A constant (tap gain constant) for specifying a value is recorded on a specific track (constant recording track) 20 of the magnetic disk 1. As the constant recording track 20, a track on the outer circumference side with a large operating margin is selected. (The tracks on the outer circumference have a low recording density and a high relative speed between the recording medium and the recording/reproducing head, so a large operating margin can be obtained.) When using a magnetic disk device, perform the following initial setting operations after turning on the power. conduct. First, the contents of the memory 9 are initialized. Then, the magnetic head 2 reads out the recording on the constant recording track 20. The read signal is amplified by the amplifier 3 and input to the transversal filter 7. The output signal of the transversal filter 7 is input to a demodulator 8, where it is demodulated into a binary signal and input to an address discriminator 19.
The address discriminator 19 discriminates the address information recorded on the constant recording track 20 together with the tap gain constant and inputs it to the memory 9 as a memory address signal 14. At this time, the read/write control signal 11 to the memory 9 is controlled to the write state, so the memory 9 receives the memory address signal 14.
The tap gain constant included in the reproduced signal 26 directly input from the demodulator 8 is stored at the address specified by and initialized. Constant recording track 2
Since 0 is selected as a track with a large operating margin, the tap gain constant stored in the memory 9 is set to have a tap gain of zero or a small value as an initial value.

As a result of the above operation, a constant (tap gain constant) specifying the tap gain of the transversal filter 7 corresponding to each track of the magnetic disk 1 and all P addresses of the magnetic head 2 is set in the memory 9.
The initialization operation is completed. When the initialization operation is completed, the magnetic disk device enters a normal use state, and at this time, the read/write control signal 11 to the memory 9 is controlled to the read state. When a magnetic disk device performs a reproducing operation, a memory address signal 12 is sent from the upper circuit to the memory 9, and this memory address signal 12 is sent to the memory corresponding to the track address and head address of the magnetic disk device in which the read operation is performed. Specify address 9. Therefore, the memory 9 sends the tap gain constant stored at the designated address to the variable attenuator 5 as a memory read signal 13. The variable attenuator 5 inputs the memory read signal 13 and attenuates the input signal with an attenuation coefficient corresponding to the specified tap gain constant and outputs it, so that the subtractor 7 subtracts and synthesizes the transversal filter output signal. 25, signals whose quality is optimized are always output for all track addresses and head addresses. Therefore, the reproduced signal 2
6 is outputted to the upper circuit via the output terminal 10 as a high quality signal with few read errors.

It should be noted that the address discriminator 19 in the above description is not particularly equipped with the address discriminator 19, and the reproduced signal 26 from the demodulator 8 is
It is also possible to adopt a method in which the address is sent to the host device, the host device determines the address, and instructs the memory 9 using the memory address signal 12.

In addition, tap gain constants corresponding to all track addresses are not recorded in the constant recording track 20, but tap gain constants for each track address at regular intervals are recorded, and in the initial operation, the tap gain constants are recorded from the constant recording track 20. It is also possible to employ a method of calculating tap gain constants corresponding to track addresses not recorded in the constant recording track 20 and storing them in the memory 9 through arithmetic processing such as replenishing the tap gain constants. Furthermore, tap gain constants corresponding to all track addresses are not recorded in the constant recording track 20, but tap gain constants corresponding to each constant track address interval are recorded as specific constants for a constant track address interval. It is also possible to adopt this method.
By employing these means, it is possible to shorten the inspection time for reproduced waveforms in the manufacturing process of magnetic disk devices and the like.

〔Effect of the invention〕

As explained above, in the present invention, tap gain constants corresponding to the waveform characteristics of read signals from all track addresses and head addresses are recorded in advance on specific tracks on a recording medium, and information is recorded. At the initial stage of use of the recording and reproducing device, the data is reproduced and stored in the memory installed in the information recording and reproducing device, and during normal information reproducing operation, the data is stored in the memory address corresponding to the track address and head address. By reading out the tapped gain constant and sending it to the transversal filter, the characteristics of the output signal are optimized and output, thereby producing the optimal reproduction signal that corresponds to variations in the characteristics of the recording medium and recording/reproducing head. This has the advantage that it is possible to transmit information, and therefore, it is possible to obtain a stable information recording/reproducing apparatus with a large operating margin, that is, a highly reliable information recording/reproducing apparatus.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 3 is a waveform diagram for explaining the operation of the transversal filter shown in FIG. 1, and FIG. 3 is a circuit diagram showing an example of a conventional information recording/reproducing device. 1...Magnetic disk, 2...Magnetic head, 3...
...Amplifier, 4...Delay device, 5...Variable attenuator, 6
...Subtractor, 7...Transversal filter,
8... Demodulator, 9... Memory, 10... Output terminal, 11... Read/write control line, 12... Address line, 13... Data output line, 20... Constant recording track.

Claims (1)

[Scope of Claims] 1. A recording/reproducing head that records or reproduces information on or from a storage medium, an amplifier that inputs and amplifies a read signal read out from the storage medium by the recording/reproducing head, and the amplifier. a transversal filter which inputs an output signal of the amplifier and a signal representing a specific constant and outputs an output signal obtained by converting the output signal of the amplifier by the specific constant; a demodulator that demodulates the data into a binary data signal and sends it out; and when the read/write control signal is in a write state, the output signal of the demodulator and the memory address signal are inputted to generate data information included in the output signal of the demodulator. is stored as the specific constant at an address specified by the memory address signal, and when the read/write control signal is in a read state, a memory address signal is input from the host device and stored at the address specified by the memory address signal. and a memory for outputting the specific constant to the transversal filter, the transversal filter inputting the output signal of the amplifier, giving it a certain delay time, and outputting it. a delay device, inputting the output signal of the amplifier, the reflected signal from the delay device, and the specific constant from the memory, and converting the output signal of the amplifier and the reflected signal from the delay device according to the specific constant; a variable attenuator that outputs an attenuated signal attenuated by a specified attenuation rate; and a variable attenuator that inputs the output signal of the delay device and the attenuated signal and outputs a signal obtained by subtracting them as an output signal of the transversal filter. and a subtracter, wherein the storage medium has previously stored on a particular track the data information corresponding to some or all of the tracks and the address of the recording/reproducing head. Device.