JPH05128820A - Tape reproducing device and method for retrieving information - Google Patents

Abstract

PURPOSE:To operate a retrieval more exactly and at a higher speed by obtaining the period of a data clock exactly and obtained exact positional data. CONSTITUTION:The cycle T of the data clock of a regenerated signal 49 is obtained by making the travelling speed of a magnetic tape 11 faster than at a reproducing time and calculating a reference clock signal 44 and the frequency of the reference clock signal 44 is made higher than at the reproducing time when information is retrieved using the information retrieving method for retrieving an optional position by reproducing positional data based on this cycle T. So as to realize this method, the reference clock signal 44 is generated and a reference clock signal generator 24 capable of changing its frequency and a controller 26 for controlling the reference clock signal generator 24 so as to make the frequency of the reference clock signal 44 at the time of the information retrieval higher than at the reproducing time are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape reproducing device such as a magnetic tape recorder and an information retrieval method for retrieving a desired information recording position from a plurality of information recorded on a tape. is there.

[0002]

2. Description of the Related Art An apparatus for recording and reproducing information on a magnetic tape, a so-called tape recorder, is constructed as shown in FIG.

The tape recorder includes a reel 60 for sending out the magnetic tape 61 during a reproducing operation, a reel 62 for winding up the magnetic tape 61 during a reproducing operation, and a tape guide 6.
3.64, magnetic head 65, magnetic tape 6 during reproducing operation
Capstan 7 to drive 1 at target speed
1. The capstan 71 is provided with a pinch roller 70 for pressing the magnetic tape 61 as needed.

A capstan motor 72 is mechanically connected to the capstan 71. The capstan motor 72 responds to a reference clock signal given from a clock signal generator 75 by a control signal from a capstan motor driver 73. It is controlled so that the rotation speed becomes high. The reference clock signal is also supplied to the signal processing circuit 80 as a timing reference when processing the input signal read from the magnetic tape 61.

The reel 60 has a reel motor 66.
However, reel motors 67 are mechanically connected to the reels 62, respectively, and the magnetic tape 61 is taken up in accordance with operation modes such as reproduction, fast-forwarding, and rewinding by a control signal given from a controller 77.

During the information reproducing operation, the magnetic tape 61 is sent from the reel 60 and travels in the direction of the arrow a, and is reeled through the tape guide 63, the magnetic head 65, the pinch roller 70, the capstan 71, and the tape guide 64. 6
It is wound up to 2.

The information signal read from the magnetic tape 61 by the magnetic head 65 is input to the signal processing circuit 80. Since the read information signal is recorded by a predetermined recording method, for example, NRZI (Non Returen to Zero Inverse) method, it is necessary to decode the signal read from the magnetic tape 61 to restore the original information signal. There is.
For this purpose, first, a reference clock signal is counted by a counter (not shown) to obtain the period T of the data clock of the read information signal, and the information is decoded based on this.

The decoded signal is output from the terminal 81 as an information output signal. Further, the position information in the signal is output to the controller 77 as an information position signal for tape position control during information retrieval.

Regarding the above-mentioned operation and other operations, the controller 77 controls these operations in accordance with an instruction signal given through the operation switch 78.

When an information reproducing operation is instructed by the operation switch 78, the controller 77 drives the take-up reel motor 6 to drive the take-up reel 62.
7, the pinch roller 70 is pressed against the capstan 71, and finally the instruction signal is output to the reproduction signal processing circuit 80 to output the information signal.

Next, when the information retrieval operation is instructed by the operation switch 78, the controller 77 sends an instruction signal to the take-up reel motor 67 in the fast-forwarding direction or in the rewinding direction according to the tape running direction to be retrieved. An instruction signal is output to the side reel motor 66. In addition,
In the case of the search operation, it is necessary to reach the target position in the shortest possible time. Therefore, the tape drive requires high-speed running, so the pinch roller 70 is not pressed.
In the case of the search operation, the function of the signal processing circuit 80 is only to output the position of the information signal recorded on the magnetic tape 61 to the controller 77, and conversely to output an unnecessary signal to an external device. Therefore, only the information position signal is output, and the instruction signal is output so as not to output the information signal. After that, the controller 77 stops the tape running when it recognizes that it is the target position by the information position signal.

By the above-described processing, the data recording type tape recorder performs the reproduction of the information signal and the high speed retrieval operation.

[0013]

However, in the above-mentioned conventional tape recorder, the magnetic tape 6 is used during the search operation.
Since the period T of the data clock cannot be accurately obtained from the signal read from No. 1, the error rate when reading the information position signal becomes high.

That is, the period T is obtained by using the count value of the reference clock signal as a time reference.
As shown in FIG. 3, the cycle T does not match the true cycle T ′ due to the phase difference between the signal read from the magnetic tape 61 (FIG. 11A) and the reference clock signal (FIG. 11B). When the cycle of the reference clock signal is Tck, the measurement error is ± Tck at maximum. Therefore, the error rate of the period T is (2Tck
/ T).

In the high speed search operation, the tape running speed becomes faster, so the cycle T becomes shorter. As a result, the above error rate becomes very large. Therefore, as described above, there is a problem that the error rate at the time of reading the information position signal becomes high and an accurate search operation cannot be performed.

[0016]

In order to solve the above-mentioned problems, the information retrieval method according to the invention of claim 1 is such that, together with the data, the position data indicating the position of the data on the tape is based on a predetermined recording clock. Using the tape recorded in, make the running speed of this tape faster than during playback,
In the information retrieval method of obtaining the period of the recording clock by counting the reference clock, and retrieving the position data based on this period to retrieve the desired position,
The feature is that the frequency of the reference clock is set higher during information retrieval than during reproduction.

A tape reproducing apparatus according to a second aspect of the invention is
In order to solve the above problem, a tape in which position data indicating the position of the data on the tape is recorded together with the data on the basis of a predetermined recording clock is used, and the running speed of the tape is set to be faster than that during reproduction. In a tape reproducing device that obtains a recording clock cycle by counting the reference clock and reproduces position data based on this cycle to search for a desired position, the reference clock is generated and its frequency is calculated. It is characterized by including a variable reference clock signal generator and a control means for controlling the reference clock signal generator so that the frequency of the reference clock is made higher at the time of information retrieval than at the time of reproduction.

[0018]

According to the structure of the present invention, a tape in which the position data indicating the position of the data on the tape is recorded together with the data on the basis of a predetermined recording clock is used, and the running speed of the tape is more than that during reproduction. In the information retrieval method for retrieving a desired position by calculating the period of the recording clock by counting the reference clock and reproducing the position data based on this period,
Since the frequency of the reference clock is made higher than that at the time of reproduction, the cycle of the recording clock can be accurately obtained. As a result, the position data can be reproduced accurately, so that the search can be performed more accurately and faster.

According to the structure of claim 2, together with the data,
By using a tape in which position data indicating the position of the data on the tape is recorded based on a predetermined recording clock, the running speed of this tape is made faster than during playback, and the reference clock is counted to count the recording clock. In a tape reproducing device that obtains a cycle and retrieves a desired position by reproducing position data based on this cycle, a reference clock signal generator that can generate a reference clock and change its frequency, and a reference clock signal generator during information retrieval. Since the control means for controlling the reference clock signal generator is provided so that the frequency of the reference clock is higher than that at the time of reproduction, the period of the recording clock can be accurately obtained. As a result, since the position data can be accurately reproduced, it is possible to realize a tape reproducing device that can perform search more accurately and at higher speed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

As shown in FIG. 1, the tape recorder of this embodiment has a reel 10 for sending out the magnetic tape 11 during a reproducing operation, a reel 12 for winding up the magnetic tape 11 during a reproducing operation, and tape guides 13 and 14. , Magnetic head 1
5. A capstan 21 for moving the magnetic tape 11 at a predetermined speed during a reproducing operation, and a pinch roller 20 for pressing the magnetic tape 11 against the capstan 21 as required. The pressing mechanism of the pinch roller 20 is not shown.

The capstan 21 is rotatably driven by a capstan motor 22. The capstan motor 22 is driven by the capstan motor driver 2
The control signal 45 from the control unit 3 controls the rotation speed to a predetermined value.

The reference clock signal generator 24 generates a reference clock signal 44 having a predetermined frequency based on a control signal 43 from the controller 26 (control means), and uses the reference clock signal 44 as a capstan motor driver 23 and a signal processing circuit 30.
Is being supplied to.

The reels 10 and 12 are rotatably driven by reel motors 16 and 17, respectively, and the reel motors 16 and 17 are controlled by control signals 41 and 42 from the controller 26, respectively.
As a result, the magnetic tape 11 can be wound at a predetermined speed according to the operation mode such as reproduction, fast-forwarding, and rewinding. The operation mode is selected by the operation switch 28.
The operation switch 28 is composed of, for example, a keyboard arranged in a grid pattern, and when the operation switch 28 is pressed, an instruction signal 47 for executing a desired operation is sent from the operation switch 28 to the controller 26.

During the reproducing operation, the magnetic tape 11 is the reel 1
0, travels in the direction of arrow A in the figure, passes through the tape guide 13, the magnetic head 15, the pinch roller 20, the capstan 21, and the tape guide 14, and then the reel 1
It is wound up to 2.

The magnetic tape 15 is moved by the magnetic head 15.
The reproduced signal 49 obtained from the above is input to the signal processing circuit 30. The signal processing circuit 30 counts the reference clock signal 44 to obtain a data clock (recording clock).
Of the reproduction signal 49, and the data is decoded from the reproduction signal 49 based on this.

For example, data (101) shown in FIG.
(01100 ...) Is recorded on the magnetic tape 11 by the NRZI method, a reproduction signal 49 as shown in FIG. When the data is 0, the polarity of the reproduction signal 49 is inverted every data cycle T, and when the data is 1, the polarity of the reproduction signal 49 is a half cycle (T / 2) of the data.
Invert every time. As described above, the NRZI method is suitable for magnetic recording because it has no DC component in the waveform of the reproduction signal 49.

The signal processing for decoding the data from the reproduced signal 49 will be described with reference to the flowchart of FIG.

The signal processing circuit 30 (FIG. 1) incorporates a counter (not shown) that counts the reference clock signal 44. The cycle T of the data clock (the cycle of the recording clock) is obtained from the count value of this counter. First, the count value is set to 0, and the data output and data clock output described later are set to low level.

Step 1 (hereinafter, step is abbreviated as S)
At, it is checked whether the reproduced signal 49 has been inverted. If there is inversion, the data output is set to high level (S2). Next, the current count value is read from the counter (S3), and the previous count value of 75, which will be described later, is read.
It is checked whether the percentage has been reached (S4). When the current count number has not reached 75% of the previous count value, the process returns to S1 and the processes of S1 to S4 are repeated.

When the current count value reaches 75% of the previous count value in S4, the data clock output is set to the high level (S5). Then, it waits until the reproduction signal 49 is inverted (S6).

When the reversal of the reproduction signal 49 is confirmed, the count value at that time is stored as the previous count value (S
7). Then, the count value is cleared (S8), the data output and the data clock output are set to the low level (S9), and the process returns to S1.

The data output waveform and the data clock output waveform obtained by the above processing are shown in FIG.
Shown in (c) and (d). The original data (FIG. 3A) is decoded by taking out the data output when the data clock output is at the high level.

The data decoded by the signal processing circuit 30 is
The demodulated signal 50 is output from the terminal 31 to an external device. Further, in order to perform control such as stopping the magnetic tape 11 at a position where desired data is recorded at the time of search, the position information (position data) included in the data is the position signal 4
8 is sent to the controller 26.

When using the above tape recorder,
First, the operation switch 2 is used to set the transfer rate of the demodulated signal 50.
Do in 8. This makes it possible to support various external devices having different input transfer rates.

In the tape recorder of this embodiment, when the transfer rate is input by the operation switch 28, the control signal 43 is sent from the controller 26 to the reference clock signal generator 24.
Will be sent. Accordingly, the reference clock signal 44 having a predetermined frequency is generated from the reference clock signal generator 24 according to the transfer rate. The reference clock signal 44 is the capstan motor driver 23 and the signal processing circuit 3.
Input to 0. As a result, the running speed of the magnetic tape 11 is controlled in synchronization with the reference clock signal 44, and the reproduction signal 49 obtained by the magnetic head 15 is decoded.

When the reproducing operation is selected by the operation switch 28, a control signal 42 is sent from the controller 26 to the take-up reel motor 17, whereby the take-up reel 12 starts to rotate. Then, an instruction to press the pinch roller 20 against the capstan 21 is issued, and finally, an instruction signal 46 is sent to the signal processing circuit 30 to output the demodulation signal 50.

When the search operation is selected by the operation switch 28, the control signal 4 is sent from the controller 26 to the reference clock signal generator 24 so as to generate the reference clock signal 44 having the highest operable frequency regardless of the set value of the transfer rate.
3 is sent.

Next, the control signal 41 or 42 is sent from the controller 26 according to the search direction. That is, when searching in the fast-forward direction, the control signal 42 is sent to the reel motor 17 on the winding side in order to rotate the reel 12 at high speed, and when searching in the rewinding direction, in order to rotate the reel 10 at high speed, The control signal 41 is sent to the reel motor 16 on the sending side.

In the search operation, the pinch roller 20 is not pressed against the capstan 21 because the magnetic tape 11 is run at high speed. Therefore, the rotation speed of the capstan 21 is independent of the running speed of the magnetic tape 11.

In the case of a search operation, the controller 2
6 need only output the position signal 48, and need not output the demodulated signal 50. Therefore, the position signal 4
8 is output, and the instruction signal 46 for not outputting the demodulation signal 50 is output from the controller 26 to the signal processing circuit 3
Sent to 0. As a result, unnecessary signals are not output to the external device.

When the controller 26 recognizes that the target position is reached based on the position signal 48, the control signal 41 or 42 is sent to the reel motor 16 or 17 to stop the running of the magnetic tape 11. Further, the control signal 43 is sent to the reference clock signal generator 24 in order to return the frequency of the reference clock signal 44 to the frequency corresponding to the set value of the transfer rate.

As described above, in the present embodiment, in the search operation of running the magnetic tape 11 at a high speed to search for desired information from a large amount of recorded information, the maximum frequency is set regardless of the transfer speed setting value. The signal processing circuit 30 is operated by using the reference clock signal 44. This shortens the cycle Tck of the reference clock signal 44,
The cycle T of the data clock in the reproduced signal 49 can be accurately obtained. Moreover, even if the cycle T is shortened due to high-speed traveling, it is possible to suppress an increase in the error rate (2Tck / T) of the cycle T. Therefore, the error rate when reading the position signal 48 from the reproduction signal 49 is reduced, and the search can be performed more accurately and at higher speed.

In the search operation, the reference clock signal 44
Since the frequency of is automatically switched to the highest frequency by the controller 26, the user can operate the operation switch 2
There is no need to reset the frequency with 8. This improves operability.

In the above-mentioned embodiments, the tape recorder using the magnetic tape 11 is mentioned as the tape reproducing apparatus, but it is also applicable to the tape reproducing apparatus using other tape recording media such as the magneto-optical tape reproducing apparatus using the magneto-optical tape. Widely applicable.

[0046]

The information retrieval method according to the first aspect of the invention is
As described above, the frequency of the reference clock is set higher during the information retrieval than that during the reproduction, so that the period of the recording clock can be accurately obtained. As a result, the position data can be reproduced accurately, so that the search can be performed more accurately and at higher speed.

The tape reproducing apparatus according to the invention of claim 2 is
As described above, the reference clock signal generator that can generate the reference clock and change its frequency, and the control that controls the reference clock signal generator so that the frequency of the reference clock is higher than that at the time of reproduction during information retrieval Since the means is provided, the period of the recording clock can be accurately obtained. As a result, since the position data can be reproduced accurately, there is an effect that it is possible to realize a tape reproducing device that can perform a search more accurately and at a higher speed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a schematic configuration diagram of a tape recorder.

2 is a flowchart showing a data decoding procedure in the signal processing circuit of FIG.

FIG. 3 is an explanatory diagram showing waveforms obtained by the data decoding procedure of FIG.

FIG. 4 illustrates a conventional example and is a schematic configuration diagram of a tape recorder.

5 is an explanatory diagram showing an error in a cycle of a data clock obtained by the tape recorder of FIG.

[Explanation of symbols]

 11 magnetic tape 24 reference clock signal generator 26 controller (control means) 30 signal processing circuit

Claims (2)

[Claims] 1. A tape in which position data indicating the position of the data on the tape is recorded together with the data on the basis of a predetermined recording clock, the running speed of the tape is made faster than that at the time of reproduction, and the reference clock is set. In the information retrieval method of calculating the period of the recording clock by counting and retrieving the position data based on this period to retrieve the desired position, the frequency of the reference clock is made higher during the information retrieval than during the reproduction. An information retrieval method characterized by the following. 2. A tape in which position data indicating the position of data on the tape is recorded together with the data on the basis of a predetermined recording clock, the running speed of the tape is made faster than that at the time of reproduction, and the reference clock is set. A reference clock that generates a reference clock and can change its frequency in a tape reproducing device that obtains a recording clock cycle by counting and reproduces position data based on this cycle to retrieve a desired position. A tape reproducing apparatus comprising: a signal generator and a control means for controlling the reference clock signal generator so that the frequency of the reference clock at the time of information retrieval is higher than that at the time of reproduction.