JPH0695410B2 - Rotating head type magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applied to, for example, a rotary head type digital audio tape recorder (hereinafter referred to as R-DAT), and more specifically, to a rotary drum. Two heads with different azimuth angles are installed at an angle of rotation of about 180 °, and a plurality of digital signals are time-compressed by these two heads and tracked diagonally to the longitudinal direction on the magnetic tape. The present invention relates to a rotary head type magnetic recording / reproducing apparatus adapted to perform recording so as to form a magnetic field and to reproduce the recorded signal by expanding the recorded signal on the time axis.

[Prior Art] FIG. 3 shows an example of a rotary head type magnetic recording / reproducing apparatus R.
It is a block diagram showing a configuration of a signal processing system of -DAT,
In the figure, (102) is a rotary drum, (101a), (101
b) is a rotary head, which is mounted on the rotary drum (102) with a rotation angle of 180 °, and one head (101a) has an azimuth angle of + 20 ° and the other head (101b) has a azimuth angle of + 20 °. The azimuth angle is set to -20 °. A magnetic tape (104) is wound around the rotary drum (102) in a rotation angle range of about 90 ° and runs. (Ten
5) is a head changeover switch, both heads (101
A recording current is alternately applied to a) and (101b), and a reproduction signal is obtained alternately.

(103) is a Hall element, and this Hall element (103) is mounted on the rotary shaft (122a) of the drum motor (122) that drives the rotary drum (102), as shown in FIG. 4 (a). , Obtains a pulse signal generated for each rotation of the rotating drum (102). A servo circuit (123) controls the rotation of the rotary drum (102), and is generated based on the pulse signal (a) obtained by the Hall element (103).
The head switch switch (105) is switched by a head switch signal as shown in FIG.

(107a) is a recording amplifier, and the heads (101a), (101
A recording signal current is passed through b), and a modulation circuit (108a) is connected to this recording amplifier (107a). A reproduction amplifier (107b) amplifies a reproduction signal from the heads (101a) and (101b), and a reproduction amplifier (107b) includes a demodulation circuit (10b).
8b) is connected. (106) is a recording / playback switching switch.

(116) and (117) are audio signal input terminals, and (11
4) is an A / D converter, (111) is RAM, (109) is a data bus, and the audio signals of the L channel and the R channel input from the input terminals (116) and (117) are A / D. It is converted into a digital signal by the D converter (114), and this digital signal is written in the RAM (111) via the data bus (109). (110) is an encoding / decoding circuit, and this encoding / decoding circuit (110) performs encoding for error correction on the recorded data in the RAM (111), and after that encoding is performed. Subcode information such as a music number is added, and a tracking control signal or the like is further added to the 8-bit to 10-bit modulated data in the modulation circuit (108a), and the data is output to the amplifier (107a) as a recording signal.

(115) is a D / A converter, (118) and (119) are audio signal output terminals, and the reproduction signal obtained by the amplifier (107b) is 8bit to 10bit in the demodulation circuit (108b).
It is converted and written to RAM (111). Thereafter, the encoding / decoding circuit (110) corrects the error in the data, the D / A converter (115) converts the audio signal into an audio signal, and outputs L signals from the output terminals (118) and (119), respectively. Output as audio signal of channel, R channel.

The series of recording / reproducing signal processing as described above is controlled by the signal generated by the clock generation circuit (113) based on an instruction from the system control microcomputer (120). A control clock is supplied from the clock generation circuit (113) to the address generation circuit (112) to operate the RAM (111) and is also used as an operation clock of the encoding / decoding circuit (110).

Next, among the operations of the apparatus having the above-described configuration, a so-called high-speed search operation for performing a cueing operation of recorded data such as audio information recorded on the magnetic tape 104 at about 200 times the normal reproduction will be described.

While controlling the rotational speed of the drum motor (122) with the servo circuit (123), the relative speed of the magnetic tape (104) to the heads (101a) and (101b) is almost the same as that during normal playback. Of the reproduction signal obtained during the high-speed search operation to be executed, the subcode data recording the music number, time, etc. is output from the demodulation circuit (108b) and sent to the microcomputer (120). The microcomputer (120) judges the beginning of the music, stops the running of the magnetic tape (104) at a desired position, returns to normal reproduction, and completes one music selection operation.

FIG. 4 is a timing chart showing the operation status during normal reproduction and high-speed search. The operation will be described with reference to FIG.

When the rotating drum (102) is controlled by the servo circuit (123) during normal reproduction, the servo reference signal (c) and the Hall element obtained by the clock generating circuit (113) as shown in FIG. 4 (c). The rotation of the drum motor (122) is controlled by the output signal from the servo circuit (123) so that the frequency and phase of the pulse signal (a) for each rotation of the drum obtained by (103) match. . At this time, a head switch signal (e) is generated by the pulse signal (a), and control is performed so that the frequency and the phase of the head switch signal (e) and the servo reference signal (c) substantially match. However, the head switch signal (e) has some jitter due to uneven rotation.

Further, as shown in FIG. 4 (d), the relationship between the reproduction signal composed of the SUB code and PCM, the head switch signal (e), and the servo reference signal (c) is as shown in FIG. 4, and the head switch signal ( The data write clock of the RAM (111) is generated based on e) and the data read clock is generated to the encoding / decoding circuit (110) based on the servo reference signal (c). Data can be written and error correction operations can be performed. By detecting both edges of the servo reference signal (c), the clock generation circuit (113) generates a control data reference signal as shown by (b1) in FIG.

This control data reference signal (b1) is a reference signal for inputting sub code data (g) related to system control such as reproduction and stop of the system control microcomputer (120). The subcode data (g) is transferred based on the clock (i) generated by the microcomputer (120) by the matching edge.

By the way, during the high speed search, the relative speed of the rotating drum (102) and the magnetic tape (104) is controlled to be constant, so that the control data reference signal (b) generated from the servo reference signal (c) falls. The edge cannot be used as the control data reference signal (b1) for determining the data transfer start timing. Since the servo control is performed at a constant relative speed, the frequency and phase of the servo reference signal (c) and the head switch signal (e) that is synchronized with the actual reproduction signal do not always match, and the rotating drum (102) This is because the frequency and phase of the head switch signal (e) fluctuate along with the change in the number of revolutions of.

Therefore, at the time of high-speed search, both edges of the head switch signal (e) are detected and a control data reference signal at the time of high-speed search as shown in FIG.
This control data reference signal (f) is sent to the microcomputer (12
The control data reference signal (b1) for determining the start of inputting the subcode data (g) with (0) is performed.

FIG. 5 shows a circuit portion for switching between the two control data reference signals (c) and (f) in the clock generation circuit (113). In FIG.
Is an input terminal for the head switch signal (e), and (6) is a D type flip-flop, to which the head switch signal (e) is input from the terminal (4). Reference numeral (5) is an input terminal of a clock (ck) having a frequency sufficiently lower than that of the head switch signal (e). The clock (ck) input from this terminal (5) causes the flip-flop (6) to switch the head switch. The signal (e) is triggered and its output is input to the flip-flop (7) of the next stage and also to the exclusive OR gate (8). The flip-flop (7) is triggered by the clock (ck),
The output is input to the exclusive OR gate (8) with a delay of one cycle of the clock (ck) with respect to the output of the flip-flop (6). Therefore, the output signal (j) of the exclusive OR gate (8) becomes a signal in which both edges of the head switch signal (e) are detected, and becomes a high level at the time of detection.

(9) is a counter, the output signal (j) is a reset input of the counter (9), and the counter (9) performs counting operation using the clock (ck),
The output of the count (9) and the clock (ck) are input to the OR gate (10), and the output of the OR gate (10) is connected to the clock input of the counter (9). Therefore, if the clock (ck) is at the low level when the control data reference signal (f) at the high speed search is at the low level, the clock (ck) is input to the counter (9). To be done. The counter (9) is an n frequency dividing counter that determines the width (tw) of the period during which the control data reference signal (f) during the high speed search is low, and the frequency division ratio is the width (tw) during which the period is low. The microcomputer (12
The width is set so that it can be read in (0).

Here, the control data reference signal (f) during high-speed search and the control data reference signal (b) during normal reproduction
Of the control data signals (k) input to the selector (11) and output from the shift register (13) are selected by the signal (k1) indicating high speed search = 0. The output (l) of this selector (11) is output from the output terminal (1) to the third
It is output to the microcomputer (120) shown in the figure. Therefore,
Due to the falling edge of the reference signal (b) or (f), the clock (i) from the microcomputer (120) via the input terminal (2) and the control data (g) via the input terminal (3). Are respectively input to the shift register (13), subjected to serial-parallel conversion in the shift register (13), and then output as a control data signal (k) to be used for controlling each part.

The output (l) of the selector (11) is the delay circuit (1
It is used as the data output clock of the shift register (13) through 2).

By using the circuit of FIG. 5 configured as described above, the transfer of control data (g) from the microcomputer (120) is synchronized with the head switch signal (e) not only during normal reproduction but also during high-speed search. Because it will start
Signal processing can be performed regardless of the rotation of the drum (102),
And the subcode data such as the song number is based on the above two control data reference signals (b) or (f),
Since the control data (g) is transferred to the microcomputer (120) immediately after it is transferred, it is easy to interface with the microcomputer (120).

[Problems to be Solved by the Invention] According to the conventional rotary head type magnetic recording / reproducing apparatus configured as described above, the reference signal synchronized with the rotational speed of the rotary head is generated in the initial startup state when the power is turned on. Since it is not output, the specified operating state may not be obtained.
Explaining this in detail with reference to the circuit of FIG. 5, since there is no control data (g) input to the shift register (13) from the microcomputer (120) at the time of initial startup, the output of this shift register (13) Is undefined, and therefore the input signal (k1) to the selector (11) is also undefined.

In addition, during high-speed search, especially when searching in the reverse direction, the rotary head may not rotate. In this case, even if the reference signal is obtained, the head switch signal is not obtained, and thus the predetermined operating state cannot be obtained. There was a problem.

The present invention has been made in order to solve the above problems, and the head operates in a predetermined operation state even when the head rotation is stopped or the rotation speed is below a predetermined rotation speed at the initial start-up and high-speed search. It is an object of the present invention to provide a rotary head type magnetic recording / reproducing apparatus capable of reliably expressing the above.

[Means for Solving the Problems] In the rotary head type magnetic recording / reproducing apparatus according to the present invention, the signal processing system for recording / reproducing is controlled on the basis of the first reference signal synchronized with the rotational speed of the rotary head during high speed search. However, during normal reproduction, the control means for controlling the signal processing system based on the second reference signal having a constant frequency corresponding to the rotation speed of the rotary head generated by the clock generating means, and the rotation of the rotary head are stopped. Alternatively, the detection means for detecting that the rotation speed is lower than a predetermined rotation speed, and the detection means that the rotation of the rotary head is stopped or the rotation speed is lower than the predetermined rotation speed at the time of initial startup or high-speed search when the power is turned on. And a selecting means for controlling the signal processing system by selecting the second reference signal when detected.

[Operation] According to the rotary head type magnetic recording / reproducing apparatus according to the present invention, at the time of initial startup when the power is turned on or at the time of high speed search,
When the rotation of the rotary head is stopped or is detected to be equal to or lower than a predetermined rotation speed, the second reference signal having a constant frequency is selected, and the signal processing system is controlled based on the reference signal. As a result, the transfer of control data from the system control microcomputer is always performed in a predetermined manner, and the control of a predetermined operation state in the signal processing system is surely executed.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

The configuration of the signal processing system of the R-DAT to which the present invention is applied is the third
Since it is the same as that shown in the figure, its description is omitted.

FIG. 1 shows a main circuit portion in a clock generation circuit (113) of a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, the same configuration as the conventional example shown in FIG. Are denoted by the same reference numerals, and their description is omitted.

In FIG. 1, reference numeral (18) is a flip-flop, and this flip-flop (18) uses the control data reference signal (f) at the time of high-speed search as a trigger input and the flip-flop (19) at the subsequent stage together with the control data reference signal (at the time of high-speed search). The presence or absence of f) is detected, and the detection signal (m) is output. (15) is an OR gate, and one of the OR gates (15) receives a signal (k1) indicating that the control data (k) output from the shift register (13) is a high speed search, The detection signal (m) is input to the other, and its output (k2) serves as the select input of the selector (11).

Next, the operation of the above configuration will be described with reference to FIG.

First, the reset signal as shown in FIG. 2 (n), which becomes low level at a frequency lower than the head switch signal (e), is flip-flop (only when the high speed search signal (k1) is low level during high speed search. Enter in 18).
Further, a trigger clock as shown in FIG. 2 (p) is input to the flip-flop (19) in which the D input is connected to the output of the flip-flop (18). Here, when the high-speed search signal (k1) is at low level, the reset signal (n)
The period from the input of to the input of the trigger clock (p) is set as the detection period (T), and this detection period (T) is set to, for example, one and a half rotations of the rotary drum (102).

If the selector (11) has selected the control data reference signal (f) during high speed search when the rotary drum (102) has stopped rotating, first the output (q) of the flip-flop (18) is output by the reset signal (n). ) Becomes high level and there is no reference signal (f) for stopping the rotating drum (102) within the above detection period (T), the flip-flop (18) is not triggered, and the clock (p) causes the flip-flop (18). The output of 19) also goes high. In this case, the detection signal (m) becomes high level, the select input (k2) of the selector (11) is also forced to be high level, and the normal control data reference signal (b) is selected and output.

Next, when the rotary drum (102) rotates, the control data reference signal (f) during high speed search is input to the flip-flop (18) within the detection period (T).
This flip-flop (18) is triggered and its output (q) goes low. This is latched by the flip-flop (19) in the subsequent stage, and the detection signal (m) becomes low level. Therefore, the select input (k2) of the selector (11) is also set to low level, and the control data reference signal (f) during high speed search is selected. The output (q) of the flip-flop (18) becomes high level by the reset signal (n) at the beginning of the next detection period (T), but the output (q) is triggered by the reference signal (f).
Returns to the low level and the next flip-flop (19)
Latches the low level and fixes the select input (k2) of the selector (11) at the low level.

If the control data reference signal (f) during the high speed search is input even once within the detection period (T) during the high speed search or the initial start-up by turning on the power by repeating the above operation, The selector (11) selects the reference signal (f), and if the reference signal (f) is not input once due to the stop of the rotary drum (102), the control data reference signal (b) during normal reproduction is selected. To do.

Therefore, the rotation drum (102) is stopped and rotated to
Since either one of the two reference signals (f) and (b) is selected and output, data transfer by the microcomputer (120) is always possible, and a predetermined operating state is obtained.

[Effects of the Invention] As described above, according to the present invention, the rotation of the rotary head is stopped at the time of initial startup when the power is turned on or during high-speed search, particularly during the search in the reverse direction, or the rotation speed is lower than a predetermined value. In that case, the fact is detected, the second reference signal having a predetermined frequency is selected, and the signal processing system for recording and reproduction is controlled based on the reference signal. Even in the above-described case where the synchronized reference signal cannot be obtained, the control data can always be input to the control means based on the output of the second reference signal, and the control operation can be surely executed as prescribed. You can In addition, the load on the control means such as a microcomputer can be reduced, and the interface with the control means can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing the main parts of a clock generation circuit in a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of each part, and FIG. A block diagram showing the entire structure of the rotary head type magnetic recording / reproducing apparatus in the embodiment and the conventional example, FIG. 4 is a timing chart for explaining the operation in FIG. 3, and FIG. 5 is a main part of a conventional clock generation circuit. It is a block diagram which shows. (6), (7), (18), (19) ... flip-flop, (9) ... counter, (10), (15) ... R gate, (11) ... selector, (13) ... Shift register,
(101a), (101b) ... rotary head, (102) ... rotary drum, (113) ... clock generation circuit, (120) ... microcomputer, (122) ... drum motor, (123) ... servo circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A signal processing system for recording / reproducing is controlled based on a first reference signal synchronized with the rotational speed of the rotary head during a high speed search, and the rotational speed of the rotary head generated by a clock generating means is controlled during a normal reproduction. A control means for controlling the signal processing system based on a second reference signal having a corresponding constant frequency, a detection means for detecting that the rotation of the rotary head is stopped or is below a predetermined rotation speed, and a power supply. If the detection means detects that the rotation of the rotary head has stopped or is equal to or lower than a predetermined rotation speed during the initial startup or high-speed search that is performed, the second
And a selecting means for controlling the signal processing system by selecting the reference signal of the rotary head type magnetic recording / reproducing apparatus.