JP2699455B2 - Digital signal reproduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a fixed head type digital tape recorder which records and reproduces analog signals such as musical sounds as digital signals encoded by PCM modulation or the like. The present invention relates to a suitable digital signal reproducing apparatus.

[Summary of the Invention]

The present invention is a digital signal reproducing apparatus suitable for use in a fixed head type digital tape recorder for recording and reproducing an analog signal such as a musical tone as a digital signal encoded by PCM modulation or the like. A digital signal track and a cue signal track on which a cue signal corresponding to the digital signal are recorded are formed on a recording medium, and a first reproducing head for reproducing the digital signal and a second reproducing head for reproducing the cue signal To the recording medium and the first and second
A digital signal processing circuit for processing a digital signal reproduced from the first reproducing head and a cue signal reproduced from the second reproducing head. A delay means for delaying the digital signal processing circuit so as to compensate for the delay time; and a switching means for switching between a cue signal reproduced by the second reproducing head and an output signal from the delay means. This allows the editing of the file to be performed accurately, and also allows the hand-cut editing to be performed accurately.

[Conventional technology]

Digital tape recorders such as PCM recorders are resistant to distortion and noise such as wow and flutter, and have a wide dynamic range. Therefore, digital tape recorders are becoming widespread in place of conventional analog tape recorders. The digital tape recorder includes a rotary head type and a fixed head type. For applications requiring a complicated editing function, a multi-channel fixed head type is mainly used.

In order to edit a digitally recorded tape, it is necessary to run the tape at a high speed or a low speed and perform a cueing operation to determine an editing point. Although it is technically possible to run at speed and perform analog reproduction, this requires not only a complicated processing circuit and an increase in the size of the entire apparatus, but also extremely high manufacturing costs. Therefore, in order to run the tape at an arbitrary tape speed and listen to the recorded contents as sound, an analog signal having the same content as the digitally recorded signal or a related analog signal (cue signal) is transmitted to another tape on the tape. It is advisable to record in synchronization with an analog signal track and use the analog signal of that track when performing cueing.

FIG. 6 shows a digital tape recorder having an analog signal track for cueing disclosed in such a conventional Japanese Patent Application Laid-Open No. 57-105813.
In the drawing, (1) is a magnetic tape having a width of 1/2 inch, for example, (2R) and (2L) are analog signal tracks for cueing, and (3) is a group of digital signal tracks. The digital signal track group (3) includes, for example, digital signal tracks (4A) to (4A) for recording audio signals, control signals, and time code signals of 24 channels, respectively.
Z).

(5) is the digital signal tracks (4A) to (4A).
A digital reproducing head comprising magnetic heads (6A) to (6Z) respectively corresponding to Z), wherein the magnetic tape (1) runs at a predetermined speed in the X direction relative to the digital reproducing head (5). The reproduction digital signal E1 generated by the magnetic head (6A) is supplied to a reproduction head amplifier (7).
The digital signal is amplified in the PCM demodulator (8), is digitally processed in the PCM demodulator (8), is demodulated into an analog signal AE1 *, and is output from an analog signal output terminal (9) to a speaker or the like (not shown). Reproduced digital signals generated by the other magnetic heads (6B) to (6Z) are processed in the same manner. Reference numeral (10) denotes a digital recording head comprising magnetic heads (11A) to (11Z) corresponding to the digital signal tracks (4A) to (4Z), respectively. The analog recording head supplied to the analog signal input terminal (12) The signal AE2 is digitally processed by a PCM modulation circuit (13), converted into a serial recording digital signal E2 * via a recording amplifier (14), and recorded on a digital signal track (4A) by a magnetic head (11A). You. Similarly, the recording digital signals are recorded on the corresponding digital signal tracks from the other magnetic heads (11B) to (11Z).

Also, (15) is an analog signal track (2R), (2L)
An analog recording / reproducing head composed of magnetic heads (16R) and (16L) corresponding to the above, respectively. During reproduction, an analog signal Q generated by the magnetic head (16R) is moved by a movable contact (17a) of a recording / reproduction switch (17). And one of the fixed contacts (17b) is supplied to an analog reproduction amplifier (18). The output signal of the analog reproduction amplifier (18) is a cue signal output terminal (19) as a cue signal (start signal) Q1.
It is supplied to a speaker or an earphone not shown.
During recording, the cue signal Q2 supplied to the cue signal input terminal (20) is supplied to the analog recording amplifier (21), the other fixed contact (17c) of the changeover switch (17) and the movable contact (17).
The analog signal Q is recorded on the analog signal track (2R) by the magnetic head (16R) via a). The magnetic head (16L) operates similarly. For example, when a guitar sound is recorded as a digital signal on a digital signal track (4A), the analog signal track (2R)
An analog signal corresponding to the digital signal is selected as an analog signal such as a guitar sound itself or a piano sound played simultaneously with the guitar sound, as an analog signal recorded as a cue signal.

[Problems to be solved by the invention]

The cue signal Q recorded as an analog signal on the analog signal track (2R) is used, for example, for locating a musical tone or the like recorded as a digital signal E2 * on the digital signal track (4A). The corresponding cue signal must be recorded at the same position in the tape running direction (width direction) of the magnetic tape (1) and maintain the in-line property. Further, even if the in-line property of the digital signal and the cue signal on the magnetic tape (1) is maintained, if there is a time lag between the analog signal obtained by reproducing the digital signal and the cue signal, substantially. Inline property is not maintained.

However, only its analog signal input terminal (12)
And also supplies the analog signal, for example the same tone queue signal input terminal (20), PCM modulation circuit (13) the delay time t ₂ required for the digital processing occurs in that time t ₂
The in-line property is not maintained because the tape moves during the operation. Therefore, conventionally, as shown in Figure 6, the digital recording head (10) relative the traveling direction of the magnetic tape (1) with respect to (X-direction) and the backward direction to the magnetic tape during the delay time t ₂ (1 ) its was fixed analog recording and reproducing head (15) at a distance d ₂ corresponding to the distance of travel. Similarly considering the delay time t ₁ required for the digital processing of the in the PCM demodulating circuit (8) at the time of reproduction, the delay time t ₁ in the X direction and the opposite direction with respect to the analog recording and reproducing head (15) the digital reproducing head at a distance d ₁ that magnetic tape (1) corresponds to the distance to travel between (5)
Is fixed, an analog signal such as a musical sound with no time lag is obtained from the analog signal output terminal (9) and the cue signal output terminal (19).

However, in the conventional digital tape recorder, it is necessary to separately provide an analog recording / reproducing head (15) in order to maintain the in-line property, and the analog recording / reproducing head (15), the digital recording head (10) and the digital The distance from the reproducing head (5) must be accurately set to a predetermined value, and there has been a disadvantage that the mechanism is complicated and the number of assembly steps is large. In addition, when the analog recording / reproducing head (15) is separately provided, it is necessary to further provide one set of tape guides for the magnetic tape (1), and the mechanism is further complicated.

In view of the above, the present invention reproduces and processes a digital signal recorded on a digital signal track to obtain a predetermined signal, and reproduces an analog signal corresponding to the digital signal recorded on an analog signal track. It is an object of the signal processing apparatus to prevent a time lag between a predetermined signal and an analog signal without separately providing an analog recording / reproducing head.

[Means for solving the problem]

The digital signal reproducing apparatus according to the present invention comprises, for example, the first
As shown in the figure, digital signal tracks (4A) to (4Z) on which digital signals are recorded and cue signal tracks (2A) on which cue signals corresponding to the digital signals are recorded.
R) is formed on a recording medium (1), and a first reproducing head (6A) to (6Z) for reproducing the digital signal and a second reproducing head (16R) for reproducing the cue signal are recorded on the recording medium. (1) and the first and second reproducing heads (6A) to
(6Z) and (16R) are arranged at the same position in the relative running direction, and the first read heads (6A) to (6R)
Z), digital signal processing circuits (23) and (24) for processing digital signals reproduced from the second reproduction head (16R), and cue signals reproduced from the second reproduction head (16R). 24) a delay means (25) for delaying so as to compensate for the delay time generated by the second reproducing head (16R) and a cue signal reproduced from the second reproducing head (16R);
Switching means (16) for switching between the output signal from (5).

(Operation)

According to the digital signal reproducing apparatus of the present invention, even if the first reproducing head (6A) and the second reproducing head (16R) are integrated and fixed, the reproduced digital signal is processed. There is no time lag between the resulting predetermined signal and its reproduced cue signal. Therefore, it is not necessary to separately provide an analog recording / reproducing head to eliminate the time lag.

Further, according to the present invention, the switching means (26) for switching between the cue signal reproduced from the second reproducing head (16R) and the output signal from the delay means (25) is provided. By switching, hand-cut editing can be performed accurately.

〔Example〕

Hereinafter, an embodiment of a digital signal reproducing apparatus according to the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a fixed head type digital tape recorder. In FIGS. 1 to 5, parts corresponding to FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted. I do.

FIG. 1 shows a main part of the digital tape recorder of this embodiment. In FIG. 1, reference numeral (22) denotes a mixed reproducing head, and the mixed reproducing head (22) includes digital signal tracks (4A) to (4Z). ) Magnetic heads (6A)
The magnetic heads (16R) and (16L) corresponding to (6Z) and the analog signal tracks (2R) and (2L) are integrated so as to be arranged at the same position in the relative running direction (X direction) of the magnetic tape (1). It was formed. As an integrated structure, in addition to a structure in which conventional bulk heads are arranged, a structure in which a thin film magnetic head is integrated can be considered.

In this example, a PCM decoder (2) is connected between the reproducing head amplifier (7) and the analog signal output terminal (9).
3) Connect the digital / analog (D / A) converter (24). The PCM decoder (23) performs PCM demodulation, deinterleaving, error correction, and the like on the digital signal E1 output from the reproducing head amplifier (7), and then converts the digital signal E1 into a D / A converter (24) as a digital signal of a predetermined sampling frequency. output to) the sound reproducing apparatus in which the PCM decoder (23) and D / a converter (24) is an analog signal AE * 1 delayed by the delay time t ₁ by a not shown from the analog signal output terminal (9) Supplied.

The reproduced analog signal Q1 of the magnetic head (16R) slidingly contacting the analog signal track (2R) is supplied to one of the input terminal of the delay circuit (25) and one of the edit mode changeover switches (26) via the analog reproduction amplifier (18). Supply to fixed contact (26b). This delay circuit (25) converts the input signal into a delay time t ₁
An output signal obtained by delaying the output signal is supplied to the other fixed contact (26a) of the edit mode switch (26). Then, the movable contact (26c) of the changeover switch (26) is connected to the cue signal output terminal (19). The movable contact (26c) of the changeover switch (26) is normally connected to the fixed contact (26a), but is connected to the fixed contact (26b) during so-called hand-cut editing as described later.

In FIG. 1, reference numeral (27) denotes a mixed recording head, and the mixed recording head (27) includes magnetic heads (11A) to (4A) corresponding to digital signal tracks (4A) to (4Z), respectively.
The magnetic heads (28R) and (28L) corresponding to (11Z) and the analog signal tracks (2R) and (2L) are integrally formed so as to be arranged at the same position in the X direction. An analog / digital (A / D) converter (2) is connected between the analog signal input terminal (12) and the recording amplifier (14).
Connect 9) and PCM encoder (30). This A / D converter (29) is an analog signal AE at a predetermined sampling frequency.
After sampling / holding 2, 2 is converted to a digital signal and supplied to the PCM encoder (30). This PCM encoder (30) records the digital signal by adding an error correction code, interleaving and PCM modulation The digital signal E2 * is supplied to the magnetic head (11A) via the amplifier (14). The digital signal E2 * are delayed by a delay time t ₂ caused by treatment with A / D converter (29) and PCM encoder (30) for the input analog signals AE2.

In this example, supplies the analog signal Q2 for indexing input queue signal input terminal (20) to the delay circuit (31), the delay circuit (31) by a delay time t ₂ the analog signal Q2 delayed Amplifier (21) converts the analog signal Q2 * obtained
To the magnetic head (28R). Further, the mixed recording head (27) by a distance D corresponding to the distance that the magnetic tape during the delay time t ₁ and t ₂ in the X direction with respect to the mixed reproducing head (22) to (1) travels Release and secure. Therefore, the interval D is equal to d ₁ + d ₂ in the conventional example shown in FIG.

A master oscillator (32) generates a master clock MCK, which is a synchronization signal for the operation of the entire digital tape recorder of the present example, and uses the master clock MCK on a tape including a capstan. Running system (33), PCM decoder (23), delay circuit (2
5), supply to A / D converter (29), PCM encoder (30), delay circuit (31), etc. Its PCM decoder (23) and P
When CM encoder (30) are each internally generate the sampling pulse SP that the master clock MCK by dividing, in the present example the frequency of the master clock MCK F _M, the frequency of the sampling pulse SP and F _S, In the state where the so-called variable speed, which will be described later, is not changed, F _M = 192F _S = 9.216 MHz F _S = 48 kHz. The delay circuit (25) and the delay time t ₁ and t ₂ each in (31) is formed as to be proportional to the period 1 / F _M of the master clock MCK.

It may the be several percent increase or decrease the frequency F _M of the master clock MCK of the master oscillator (32) in this embodiment.
If varying the master clock MCK of decreasing the frequency F _M of the master clock MCK Fig. 2 A master clock MCK ₁ in FIG. 2 B, capstan speed or PCM decoder tape running system (33) ( The operation of 23) is also delayed proportionally. Therefore, the analog signal output terminal (9)
Sampling period of the reproduced analog signal AE1 * more resulting substantially frequency decreases changed to T ₁ shown in FIG. 3 B from T shown in Figure 3 A. This is by increasing or decreasing the frequency F _M of the master clock MCK of the master oscillator (32), means that it can increase or decrease the frequency of the reproduced analog signal AE1 *, means that facilitates a so-called variable speed operation . In this example, since the PCM decoder (23) and the delay circuit (25) operate in synchronization with the master clock MCK, the delay caused by the PCM decoder (23) and the D / A converter (24). the time t ₁ and the delay time t ₁ by the delay circuit (25) varies in the same way in proportion to the change of the master clock MCK. Similarly, PCM encoder (30) and changes in the same way in proportion to the change of the master clock MCK A / D converter (29) by the delay time t ₂ and the delay time t ₂ by the delay circuit (31) I do. Therefore, according to this example, even when the frequency of the reproduced analog signal AE1 * is changed by the variable speed operation, there is an advantage that it is not necessary to readjust the delay circuits (25) and (31).

Further, an example of a delay circuit (25) which can be obtained a delay time t ₁ is proportional to the period 1 / F _M of the master clock MCK in Figure 4. In FIG. 4, (34) is a terminal to which the master clock MCK is supplied, (35) is a control circuit, and (3)
6) is a data bus, (37) is an address bus, (38) is a sample / hold circuit, (39) is an A / D converter, (40) is a writable memory (RAM), and (41) is a latch circuit. ,
(42) is a D / A converter. The control circuit (35) synchronizes with the master clock MCK by the sample / hold circuit (3
8) and operating the A / D converter (39) to convert the analog signal Q1 supplied via the analog regenerative amplifier (18) into a digital value. The control circuit (35) uses the address bus (37) to sequentially write the digital value from a predetermined address of the RAM (40), and shifts a predetermined address from the predetermined address of the RAM (40). The digital value is sequentially read out and held in the latch circuit (41). Therefore, the output of the latch circuit (41) is connected to the D / A converter (42).
The analog signal Q1 * obtained by the conversion is delayed by a predetermined time with respect to the supplied analog signal Q1. In this case, it is possible to match the predetermined time delay t ₁ by adjusting the deviation of the address of the writing and reading of the RAM (40). Further, the delay circuit (25) so operates synchronously with the master clock MCK, the delay time t ₁ changes in proportion to the period 1 / F _M of the master clock MCK.

As the delay circuit (25), for example, in addition to the example in FIG.
A delay circuit using a CCD or a delay line formed by winding a conductive wire on a bobbin wrapped with copper tape via an insulating tape can be used.

Using the digital tape recorder of this example, the analog signal AE2 is PCM modulated and recorded on the digital signal track (4A) of the magnetic tape (1), and the analog signal Q2 for cueing is recorded on the analog signal track (2R). To explain the operation when recording, an analog signal supplied from a microphone or the like (not shown) is input to an analog signal input terminal (12).
AE2 is, A / D converter (29) and PCM encoder (30) by the digital signal track as a digital signal E2 * delayed by time t ₂ from the analog signal AE2 (4A)
Will be recorded. Also, the cue signal input terminal (20) is supplied with the analog signal Q2 for cueing supplied from the microphone or the like by the delay circuit (31).
Q2 that is recorded on an analog signal track (2R) as from time t ₂ delayed analog signal Q2 *.

Therefore, according to this embodiment, since the digital signal E2 * and the analog signal Q2 * are recorded with the same delay time, the digital signal E2 * and the analog signal Q2 * are recorded on the magnetic tape (1) by the integrated recording head (27). The digital signal E2 * and the analog signal Q2 * are recorded at the same position in the relative running direction (X direction) of the magnetic tape (1), and there is an advantage that the so-called in-line property is maintained.

When the digital tape recorder of the present embodiment is used to reproduce digital signal E1 recorded on digital signal track (4A) and analog signal Q1 recorded on analog signal track (2R) of magnetic tape (1). To explain the operation, the movable contact (26c) of the edit mode changeover switch (26) is switched to the other fixed contact (26a) and the digital signal E1 and the analog signal Q1 on the magnetic tape (1). It is assumed that the in-line property is maintained.

In this case, the digital signal E1 reproduced from the magnetic head (6A) sliding on the digital signal track (4A)
Is the time in the PCM decoder (23) and D / A converter (24)
t ₁ only is converted to an analog signal AE1 * delay, is supplied to an external speaker or the like from the analog signal output terminal (9). Further, the analog signal Q1 reproduced from sliding contact magnetic head to an analog signal track (2R) (16R) is converted into an analog signal Q1 * which is delayed by a time t ₁ in the delay circuit (25), cue signal output It is supplied from a terminal (19) to an external earphone or the like. Therefore, according to the present embodiment, by using one mixed reproducing head (22) formed by combining the magnetic heads (6A) and (16R), the analog signal AE1 * and the cue for cueing without time lag are mutually eliminated. Of the analog signal Q1 *.

Furthermore, in this example, the PCM encoder (30) and the delay circuit (3
1) etc. are driven in synchronization with the master clock MCK of the master oscillator (32), so that the delay time of the analog signal AE2 and the delay time of the analog signal Q2 for cueing are changed by the master clock MCK. And change in the same way. Therefore, according to this example, the master clock MC
Even by changing the frequency F _M of K performing variable-speed operation, and the analog signal is recorded on an analog signal track (2R) Q2 * digital signal E2 * and recorded in the digital signal track (4A) There is a benefit that the in-line nature of is kept. Similarly, even when the variable speed operation is performed, there is no time lag between the reproduced analog signal AE1 * and the reproduced analog signal Q1 * for cueing.

Next, the operation when so-called "hand-cut editing" is performed using the digital tape recorder of this embodiment will be described. First, in FIG. 1, the movable contact (26c) of the edit mode changeover switch (26) is fixed to one side. Switch to the contact (26b) side.

In the hand-cut editing, the editor puts marks B1 and B2 on the two editing points of the magnetic tape (1) as shown in FIG. 5A and sandwiches them between the microphones B1 and B2 as shown in FIG. 5B. Means to manually replace the damaged part with another editing tape (43). Therefore, it is necessary to accurately perform cueing and determine the edit point. In this example, when the movable contact (26c) of the edit mode changeover switch (26) is switched to the one fixed contact (26b) side, the reproduction is performed from the magnetic head (16R) sliding on the analog signal track (2R). The cue analog signal Q1 thus obtained is supplied to an earphone or the like from the cue signal output terminal (19) without any delay time. Therefore, while listening to the sound of the earphone or the like, the running of the magnetic tape (1) is stopped at a desired place to stop the fifth step.
As shown in FIG. A, the first editing point is determined by attaching the microphone B1 to the portion of the magnetic tape (1) that overlaps the mixed reproduction head (22). Next, the magnetic tape (1) is again moved in the X direction at a high speed to a low speed to stop the magnetic tape (1) at the next desired place. Then, the magnetic tape (1) overlapping the mixed reproducing head (22) indicated by the dashed line (22 *)
The second editing point is determined by adding the mark B2 to the portion.

As described above, since the digital tape recorder of the present embodiment is provided with the edit mode changeover switch (26), there is an advantage that hand-cut editing can be performed easily and accurately.

In this example, the mixed recording head (27) is provided at a distance of D (= d ₁ + d ₂ ) in the X direction from the mixed reproducing head (22), which enables so-called “synchronous recording”. Becomes This synchronous recording means recording another digital signal on the digital signal track (4A) in synchronization with the digital signal recorded on the digital signal track (4Z), for example (while maintaining the in-line property). Converted into an analog signal by the digital signal track (4Z) PCM decoder of the delay time t ₁ that is not shown the reproduced digital signal of the sliding contact magnetic head (16Z) to the or the like in the present embodiment, release the analog signal from the earphone or the like Let it sound. Then, the analog signal AE2 to be recorded in the analog signal input terminal (12) in accordance with the sound emitted from the earphone or the like.
Supplying, the analog signal AE2 is recorded into a digital signal track from the magnetic head (11A) is converted into a digital signal E2 * in the delay time t ₂ (4A). In this case, the total delay time from when the digital signal is reproduced by the magnetic head (16Z) to when the digital signal is recorded by the magnetic head (11A) is (t ₁ + t ₂ ). However, the distance corresponding to the distance the magnetic tape (1) travels in the X direction between the In this example the mixed recording head (27) Mixed reproducing head (22) with respect to time (t ₁ + t ₂₎ D Just fixed apart.

Therefore, according to the present embodiment, only by inputting a desired analog signal from the analog signal input terminal (12) or the like in accordance with the analog signal output from the analog signal output terminal (9) or the like, the synchronization with the in-line property maintained. There is a benefit to be able to record.

It should be noted that the present invention is not limited to the above-described embodiment, and can be modified without departing from the gist of the present invention, for example, by arranging an erase head and a cross fader circuit.

〔The invention's effect〕

Since the digital signal reproducing circuit of the present invention is constructed as described above, the digital signal and the cue signal related thereto have no in-line property, i.e., no reproduction shift, in a state where the digital reproducing head and the cue signal reproducing head are integrated. This has the advantage that normal editing can be performed accurately and hand-cut editing can be performed accurately.

[Brief description of the drawings]

FIG. 1 is a structural view including a partial perspective view showing a main part of an embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining a variable speed operation of the embodiment, and FIG. FIG. 5 is a diagram showing an example of a delay circuit (25) in the example of FIG. 1, FIG. 5 is a diagram for explaining the hand-cut editing of the embodiment, and FIG. 6 is a part showing an example of a conventional digital tape recorder. It is a lineblock diagram including a perspective view. (1) is a magnetic tape, (2R) and (2L) are analog signal tracks, (4A) to (4Z) are digital signal tracks, (6A) to (6Z), (11A) to (11Z), ( 16R),
(16L), (28R), (28L) are magnetic heads, (22)
Is a mixed playback head, (23) is a PCM decoder, (24) is D / A
Converter, (25) is a delay circuit, (29) is an A / D converter, (3
0) is a PCM encoder, and (31) is a delay circuit.

Claims (1)

(57) [Claims] A digital signal track on which a digital signal is recorded and a cue signal track on which a cue signal corresponding to the digital signal are recorded are formed on a recording medium, and a first reproducing head for reproducing the digital signal; A second reproducing head for reproducing a cue signal is arranged at the same position in a relative traveling direction between the recording medium and the first and second reproducing heads, and a digital signal reproduced from the first reproducing head is provided. Digital signal processing circuit, delay means for delaying a cue signal reproduced by the second reproducing head so as to compensate for a delay time generated in the digital signal processing circuit, and reproduction by the second reproducing head. Switching means for switching between the selected cue signal and the output signal from the delay means. Digital signal reproduction device.