JPH0668863B2 - Tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a helical scan type tape recorder, in which the relative speed between the rotary head and the tape is constant when the normal reproduction mode is switched to the high speed reproduction mode. And then
The present invention relates to a tape recorder capable of accurately reading a recording signal on a tape.

[Prior Art] Conventionally, when a high speed reproduction mode is set in a helical scan type tape recorder, a dedicated fixed head is used and a tape traveling speed is controlled to be constant by a detection signal from the fixed head. According to the tape traveling speed and the tape traveling direction, the rotating speed of the drum to which the rotating head is attached is changed to keep the relative speed between the rotating head and the tape constant.

[Problems to be Solved by the Invention] In the conventional helical scan type tape recorder as described above, since the fixed head for high-speed reproduction is incorporated as described above, the structure of the tape running system becomes complicated. ,
It was disadvantageous in terms of size, weight reduction and cost of the device.

The present invention has been made to solve the above problems, and the relative speed between the rotating head and the tape at the time of high speed reproduction can be controlled by the reproduction signal of the rotating head without using a dedicated fixed head. An object of the present invention is to provide a tape recorder that can be kept constant and that can very accurately read a recording signal on a tape during high-speed reproduction to improve the accuracy of high-speed search such as cueing.

[Means for Solving the Problems] The helical scan type tape recorder according to the present invention extracts a specific signal component having an arbitrary frequency from the reproduction signal of the rotary head, and outputs the measured value and the reference value of the frequency. At the same time as controlling the rotational speed of the drum by adding the drum rotational speed correction data according to the difference of the to the drum rotational speed control loop, the rotational speed of the speed-controlled drum is monitored,
It is characterized in that the tape running speed is maintained within a set range by controlling the rotation speed of the reel.

[Operation] In the present invention, the specific frequency component is extracted from the reproduction signal of the rotary head, and the drum rotation speed control data is supplied to the drum rotation speed control loop according to the difference between the count value of the extracted frequency and the reference value. Because of this, it is possible to make the relative speed with the rotary head constant without using a dedicated fixed head, simplifying the configuration of the tape running system and achieving highly accurate drum rotation control. Becomes possible,
As a result, the tape running speed is controlled within the set range, so even if the tape running speed changes due to changes in the winding diameter as high-speed playback progresses, the fluctuation range is small, and accurate high-speed playback is always possible. Is possible.

[Examples] Prior to describing the examples of the present invention, the principle of the present invention will be described.

The helical scan tape recorder does not use a fixed head, but a signal recorded on the tape forms a signal for tracking a track on the tape, that is, a tracking error signal, thereby performing tracking. Automatic Track Finding (hereinafter referred to as ATF)
Some have adopted the method.

As an example, a rotary head type digital audio tape recorder (hereinafter referred to as R
-DAT) and its track pattern is as shown in FIG. A signal for performing ATF is recorded in the shaded portion of FIG. 2 (the difference in the angle of the diagonal line indicates the difference in recording azimuth), and the details of the recording pattern are as shown in FIG. .

As shown in FIG. 3, signals of four types of frequencies from 1 to 4 are recorded in the ATF signal recording area. The present invention does not have the gist of the ATF system, and it is well known how to perform tracking by these signals, and therefore detailed description of the operation will be omitted.

Now, when this R-DAT is played normally, the relative speed between the rotary head and the tape is a predetermined value, so ATF signals 1 to 4
Becomes a predetermined frequency, but if the running speed of the tape changes, the relative speed of the rotating head and the tape will shift, so
As a result, the frequencies of the ATF signals 1 to 4 also change.

This invention pays attention to the above, and detects the frequency of the ATF signal and controls the rotational speed of the drum by controlling the rotational speed of the drum as the traveling speed of the tape is arbitrary with respect to the relative speed difference between the rotating head and the tape. It is intended to correct the deviation, and as the drum rotation speed and tape running speed are changed in order to keep the relative speed constant, the signal readable area becomes narrower as shown in FIG. However, the signal cannot be read accurately, but by attempting to control the running speed of the tape according to the rotation speed of the drum before that, it is possible to eliminate a signal reading error.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration of the embodiment. The signal recorded on the tape (1) is reproduced by the rotary head (2) and amplified by the head amplifier (3). The output signal of the head amplifier (3) is fed to a frequency discriminator (low-pass filter or band-pass filter) (4) that passes only one frequency signal (an example of a specific signal component) and a second waveform shaping circuit (5b). Is entered. The signal that has passed through the frequency discriminator (4) is input to the first waveform shaping circuit (5a), where it is converted to a TTL level signal and transmitted to the next-stage 1-frequency counter (6). ,here,
Clock signal with a frequency sufficiently higher than one signal frequency (20)
Thus, one signal frequency is counted.

On the other hand, the signal converted to the TTL level by the second waveform shaping circuit (5b) is input to the 2 frequency detection circuit (8) f3 frequency detection circuit (9), where the 2 signal and 3 signal are detected. Be done. As shown in the recording pattern of FIG. 3, one signal is always recorded next to the two signals or the three signals, so that the one-signal frequency is already counted when the two or three signals are detected.

Therefore, the count value of the 1-frequency counter (6) is latched to the digital comparator (7) via the OR gate (10) by the output signal of the 2-frequency detecting circuit (8) or the 3-frequency detecting circuit (9). . At this time, one signal is reproduced by the reverse azimuth head, but its frequency is sufficiently low and is not significantly affected by the azimuth effect, which is not a problem.

The speed control servo loop for controlling the rotation speed of the drum to which the rotary head (2) is attached includes a drum motor (14) and a drum rotation pulse (hereinafter referred to as a drum FG pulse) generated by the drum motor (14). ), And a third waveform shaping circuit (5) for converting the output signal of this preamplifier (15) into a TTL level signal.
c) and F-V that converts the period of drum FG pulse into voltage
It is composed of a conversion circuit (16), a digital adder (11), a low-pass filter (12), and a first motor drive amplifier (hereinafter referred to as MDA) (13a). The operation of this speed control servo loop is well known and will not be described.

In the digital comparator (7), the preset reference value (1 signal frequency) (21) is compared with the latched count value in magnitude, and data (22) for correcting the number of rotations of the drum according to the difference is compared. ) Is transmitted to a digital adder (11) which is a component of the speed control servo loop.

The digital adder (11) contains the rotation speed correction data (2
The rotation speed deviation data (23) output from the FV conversion circuit (16) is also input together with 2), and these are added together to obtain highly accurate data as the low pass filter (12) of the next stage. PWM output to. The low-pass filter (12) smoothes the PWM signal (24) and outputs the analog signal (2
5), which is converted by this signal (25)
The drum motor (14) is driven via the first MDA (13a).

With the above operation, the rotation speed of the drum is controlled so that one signal frequency reproduced by the rotation head (2) is always a predetermined frequency, and the relative speed between the rotation head and the tape is kept constant. ing.

As described above, the rotation speed of the drum is controlled so that the relative speed between the rotation head and the tape is constant with respect to an arbitrary tape traveling speed. However, the signal recorded on the tape (1) is controlled. In order to read accurately, the running speed of the tape must be limited.

High-speed playback is usually performed for the purpose of searching for the beginning of the PCM music signal recorded on the tape, and the information necessary for searching such as information indicating the beginning of the song and time information is the track format SUB1 shown in FIG. It is recorded in the subcode recording area of SUB2.

The block format of the signal recorded in this sub-code recording area is as shown in FIG. 4, and the sub-code information part (27) contains information indicating the beginning of the song, and the data part (28) contains the time. Information is recorded. A sync signal (26) is added to the beginning of the block, and the information of other parts can be read only after detecting the sync signal (26).

As shown in FIG. 5, the signal readable area is only a period in which the azimuth angle of the rotating head tracing the tape and the track recorded at the same azimuth are passed, and when the relative speed is constant, The relationship between the tape traveling speed and the readable block length is as shown in FIG.

In order to read the subcode signal accurately, the sync signal (26) of one subcode block must be detected and the information recorded in that block must be read, so the readable block length is at least 2 blocks. Will be needed.

According to FIG. 6, the tape running speed when the readable block length becomes 2 blocks is about 200 times the normal running speed, and the tape running speed must be limited to this value or less. When the sync signal (26) is detected and only the subcode information part (27) following it is read,
Since it is not necessary to read all one block, one block is sufficient as the readable block length, and the tape running speed at that time is limited to about 380 times speed according to FIG.

To keep the relative speed of the rotating head and tape constant,
Number of drum rotations (rotational speed) relative to tape running speed
Must be maintained in the relationship shown in FIG. Therefore, if the relative speed is kept constant, the tape running speed can be calculated by detecting the rotational speed of the drum, and the tape running speed can be controlled.

The embodiment of the present invention embodies the above,
In FIG. 1, the drum FG pulse generated from the drum motor (14) is amplified by the preamplifier (15), and the amplified signal is converted into a TTL level signal by the third waveform shaping circuit (5c). While being input to the F-V conversion circuit (16),
It is also input to the drum FG frequency counter (17).

The drum FG frequency counter (17) counts the frequency of the drum FG pulse, that is, detects the number of rotations of the drum,
The result is output to the reel motor control circuit (18) at the next stage. In the reel motor control circuit (18), when the system shifts from the normal playback mode to the high-speed playback mode, a signal for increasing the tape running speed is output, and at the same time, the number of rotations of the drum is monitored and the number of rotations reaches a predetermined value. Approximately 3000 rpm during high-speed playback in the forward direction, and approximately 100 rpm when the tape running speed is set to 200 times the normal running speed during high-speed playing in the reverse direction, as shown in FIG.
The reel motor (19) is driven via the second MDA (13b) so as not to exceed 0 rpm to control the tape traveling speed.

FIG. 8 shows changes in the tape running speed and the number of rotations of the drum after shifting to the high speed reproduction mode. FIG. 8 shows that the tape running speed control is set to 200 times the normal running speed.

In the above embodiment, the tape traveling speed is limited by the number of rotations of the drum, but the tape traveling speed can be limited by detecting the number of blocks that can be read from the reproduction signal. This is clear from the relationship shown in FIG.

[Advantages of the Invention] As described above, according to the present invention, the relative speed between the rotating head and the tape can be made constant without using a dedicated fixed head. It is possible to simplify, reduce the size and weight of the entire device, and reduce the cost.

Moreover, during high-speed playback, the tape running speed can be controlled within a range in which the signal recorded on the tape can be accurately read regardless of changes in the reel winding diameter. That is, it is possible to prevent the beginning of a song from being searched, that is, to miss a cue and improve the search accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of a tape recorder according to the present invention, FIG. 2 is a diagram showing a track pattern of R-DAT, FIG. 3 is a detailed diagram of a recording pattern of an ATF signal, and FIG. The figure shows the block format of the sub-code part, FIG. 5 shows the reproduced signal envelope waveform when the rotating head crosses the track, and FIG. 6 shows the relationship between the tape running speed and the readable block length.
FIG. 7 is a correlation diagram between the tape running speed and the drum rotation speed, and FIG. 8 is a view showing changes in the tape running speed and the drum rotation speed in the high speed reproduction mode. (2) …… Rotary head, (4) …… Frequency discriminator, (5
a) to (5c) ... Waveform shaping circuit, (6), (7) ... Frequency counter, (7) ... Digital comparator,
(8), (9) ... frequency detection circuit, (11) ... digital adder, (16) ... FV conversion circuit, (18) ... reel motor control circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A helical scan type tape recorder, comprising means for extracting a specific signal component included in a signal reproduced by a rotary head attached to a drum, and frequency of the extracted specific signal component. A means for counting and a digital comparator for comparing the count value with a reference value and outputting drum rotation speed correction data according to the difference are provided, and the drum rotation speed correction data of the digital comparator is controlled by the drum rotation speed control servo. The drum rotation speed control servo loop is provided with means for detecting the rotation speed of the drum in consideration of the loop and detecting the rotation speed of the drum, and the tape running speed is determined based on the output signal of the drum rotation speed detecting means. A tape recorder characterized by controlling the rotation speed of a reel so as to be maintained within a set range.