JPS59213005A - Pcm sound recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute reproducing at a variable speed even in case of a device of a rotary head type by constituting so that a tape running speed, a cylinder rotating speed and a signal processing speed are varied at a prescribed ratio. CONSTITUTION:In case when a magnetic tape 10 sound-recorded at a tape running speed V and a cylinder rotating speed W is reproduced at a speed of K times, a speed change quantity K is given to a control terminal 38 of a clock generating circuit 36. Frequency of each clock C1-C3 is multiplied by K, the tape running speed is multiplied by K, and the cylinder rotating speed is also multiplied by K. As a result, the magnetic head 20 traces correctly a signal recording area on the magnetic tape 10, and the recording information is reproduced correctly. In this case, a speed of a signal train reproduced by the magnetic head 20 also becomes K times, this signal train of K times is processed by a signal processing part 22 to which a signal processing clock C3 having a frequency of K times of a usual time is given, and an analog signal reproduced at a speed of K times is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PCM recording and reproducing device, in particular, a magnetic head is attached to a cylinder that rotates at a predetermined inclination with respect to the running direction of a magnetic tape, and an analog signal is digitized through the magnetic head. The present invention relates to a so-called rotating head type PCM recording/playback device for recording and playing back PCM signals.

This type of PCM recording and reproducing apparatus "t1" is basically constructed as shown in FIG.

The capstan 12 is controlled to a constant rotation speed by a control circuit 14, and as a result, the magnetic tape 10 runs at a constant speed V in the direction of the arrow.

Tape! Schilling I6 rotatable with a predetermined inclination with respect to the running direction of 0
is provided. The cylinder 16 has a rotation control circuit 18
is rotated at a rotational speed W in the direction of the arrow. The shilling 16 is in contact with the magnetic tape 10 and has a P
Two magnetic heads 2o for recording or reproducing CM signals
is installed.

The two magnetic heads 20 are alternately connected to a digital signal processing circuit 26 via a switching circuit 24 in the signal processing section 22 . During recording, an analog audio signal applied to the input terminal 28 is converted into a digital signal by the A/D converter 30 and input to the processing circuit 26.
Here, encoding processing necessary for recording is performed, and a 70PCM signal is supplied to the magnetic head 20. Further, during reproduction, the PCM signal reproduced by the magnetic head 20 is decoded by the processing circuit 26, further converted into an analog audio signal by the D/A converter 32, and outputted to the output terminal 34.

FIG. 2 shows a recording pattern by the magnetic head 20 on the magnetic tape IO. As mentioned above, the magnetic tape 10 is running at a constant speed V, has a constant inclination relative to this, and the magnetic head 20 is rotated at a constant rotational speed W. A single recording pattern has a constant inclination with respect to the longitudinal direction of the tape 10. Of course, during playback, the speeds of the magnetic tape lO and the magnetic head 20 are controlled to be the same as during recording, and the relative relationship between the two is the same as during recording, so that the signals recorded in the recording pattern shown in Fig. 2 are correctly magnetically recorded. The head 20 reproduces the data.

Incidentally, it is strongly desired that this type of PCM recording/playback device also have a variable speed playback function for slowing down or speeding up the playback speed, as in general analog tape recorders. however,
The above-mentioned conventional rotary-rad type PCM recording and reproducing apparatus cannot perform this 5" speed change and 11" raw. That is, a magnetic tape on which signals are recorded at a tape running speed V and a head rotation speed W as shown in FIG. When reproducing 0,
As shown in Figure 3, if the running speed of the Qi 110 is doubled from that during recording, the area indicated by the dotted line in the same figure is the magnetic head 20.
will be traced, making it impossible to correctly reproduce the information recorded in the area shown by the solid line.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide a rotating head type PCM recording/playback device that can perform variable speed playback similar to a general analog tape recorder.

In order to achieve the above object, the present invention provides a tape running control means for controlling the running speed of a magnetic tape in proportion to the frequency of a running control clock, and a tape running control means for controlling the running speed of a magnetic tape in proportion to the frequency of a running control clock; A cylinder rotation control means for controlling and P reproduced from a magnetic tape by a magnetic head.
a signal processing means for processing a CM signal in synchronization with a signal processing clock and demodulating it into an analog signal; and changing the frequencies of the travel control clock, the rotation control clock, and the signal processing clock while maintaining a constant relative ratio. The present invention is characterized in that it is provided with a clock variable means for changing the clock.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 4 shows the configuration of a PCM recording and reproducing apparatus according to an embodiment of the present invention. In this figure, parts that are the same as or correspond to those in FIG. 1 are designated by the same reference numerals.

In FIG. 4, an ffi control circuit 14 controls the rotation of the capstan 12 to control the running speed of the magnetic tape 10.
operates based on the clock Ct of 36 clock generation circuits, and generates the tape l in proportion to the frequency of the clock C1.
Controls the running speed of O.

The control circuit 18 that controls the rotation of the cylinder 16 operates according to the clock C2 from the clock generation circuit 36, and controls the rotation speed of the cylinder 16 in proportion to the frequency of the clock C2.

The signal processing unit 22 that performs signal processing for recording and playback operates in synchronization with the clock C3 from the clock generation circuit 36, and the signal processing unit 22 performs signal processing for recording and playback.
The processing speed of D conversion, D/A conversion, encoding and decoding is determined by clock C3.

The clock generation circuit 36 generates the tape running control clock CI, the cylinder rotation control clock C2, and the signal processing clock C3 in response to a speed change command applied to the control terminal 38.
It is configured to change the frequency of the signal while maintaining a constant relative ratio.

In other words, during normal playback (same as when recording), the frequency of the tape running control clock C1 is set to ■, the frequency of the cylinder rotation control clock C2 is set to W, and the frequency of the signal processing clock C3 is set to 8.
Then, when the variable speed amount K is given to the control terminal 38, each clock CI, C2°C3
Set the number of cycles to -V, -W, and -8 respectively.

As explained above, when a magnetic tape IO recorded at the tape running speed [v and cylinder rotational speed W is to be played back at twice the speed, the speed change amount K is input to the control terminal 38 of the clock generation circuit 36. give. Then, as described above, the frequencies of the clocks C1+C2+C3 are respectively multiplied, the tape running speed is multiplied, and the cylinder rotational speed is also multiplied. As a result, as shown in FIG. 5, the magnetic head 20 correctly traces the signal recording area of the magnetic tape running speed, and the recorded information is correctly reproduced.

However, the speed of the signal train reproduced by the magnetic head 20 is also doubled. This signal sequence is processed by the signal processing unit 22 which is given a signal processing clock C3 having twice the normal frequency, and an analog signal reproduced at K times the speed is obtained.

FIG. 6 shows a concrete structure 11 of the clock generation circuit 36. As shown in FIG. The clock generation circuit 36 shown in this figure includes a crystal oscillator 40 that generates an original clock a with a sufficiently high frequency, and variably divides the frequency of the original clock a according to a command value applied to a control terminal 38. A J-variable frequency divider 42 and each of the above clocks cl, c2 using the clock b frequency-divided by this as a phase reference signal.
．． It consists of PLL (phase locked loop) type oscillator circuits 441, 46, and 48, respectively, which create the signals c3. Here, as long as the normal speed command value is given to the control terminal 38,
The output frequency of the Jf frequency divider 42 corresponds to the sampling frequency of the PCM recording/reproducing device.When the command value is K, the output frequency is twice the sampling frequency. As a result, three types of clocks C1, C2, and C3 whose frequencies are proportionally controlled as described above are created.

In the above embodiment, it has been explained that the tone of the reproduced sound is doubled when the variable speed is reproduced, but the present invention is not limited to this, and by changing the signal processing method during reproduction. You can change only the pitch without changing the tone of the sound.

As explained in detail above, the PCM recording and reproducing apparatus of the present invention is configured so that the tape running speed, cylinder rotational speed, and signal processing speed can be changed at a constant ratio, so that this type of apparatus can also be used. Variable speed playback is possible.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of a conventional PCM recording and playback device, Fig. 2 shows a preferred recording pattern of the PCM recording and playback device, and Fig. 3 shows an EJ A head trace pattern diagram during recording and reproduction showing that variable speed reproduction cannot be performed, FIG. 4 is a PC according to an embodiment of the present invention.
A block diagram of the M recording/playback device, FIG. 5 is a head trace pattern diagram for recording and playback when variable speed playback is performed with the device of the present invention, and FIG. 6 is a block diagram showing a specific example of the clock generation circuit in FIG. 4. It is a diagram. The same members in each figure are given the same reference numerals, 10 is a magnetic tape, 12 is a capstan, 14 is a cabstan control circuit,
I6 is a Schilling, 18 is a Schilling rotation control circuit, 20 is a magnetic head, 22 is a signal processing section, 36 is a clock generation circuit, and 38 is a control terminal. Agent Patent attorney Masuo Oiwa (and 2 others) Figure 1 20 Figure 2 0 ■ Figure 3 n K・■ Figure 4 0 Figure 5 n -v

Claims (1)

[Claims] (1) In an apparatus that has a cylinder that rotates at a predetermined inclination with respect to the running direction of a magnetic tape, and records and reproduces a PCM signal obtained by digitizing an analog signal using a magnetic head attached to the cylinder, the magnetic a tape running control means for controlling the running speed of the tape in proportion to the frequency of the running control clock; a shilling rotation control means for controlling the rotation speed of the shilling in proportion to the frequency of the rotation control clock; a signal processing means for processing a PCM signal reproduced from the magnetic tape in synchronization with a signal processing clock and demodulating it into an analog signal; A PCM recording and reproducing device characterized by comprising a clock variable means for changing the clock while maintaining the ratio.