JP2523844Y2 - Audio system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to an audio system including a PCM audio reproducing device such as a compact disk player and a tape recorder for recording an analog reproduction signal of the PCM audio reproducing device on a magnetic tape. About the system.

[Related Art] When a music signal recorded on a compact disc is reproduced and recorded on a magnetic tape with normal recording sensitivity, the reproduction signal level of the compact disc player is too high for the following reasons for the magnetic tape. There have been problems that the recorded music signal is distorted, and conversely, the reproduction signal level is too low and the SN ratio becomes small.

The dynamic range of a compact disc is about 40 dB wider than that of a magnetic tape.

Compact discs have a large recording level difference for each label, and the maximum peak level differs by 18 dB.Also, even on the same label, depending on the music,
Some have a maximum peak level of only -13dB.

In order to solve this, conventionally, after performing automatic bias adjustment before recording, the recording level of the tape deck was adjusted to an optimum level, or recording was performed with a tape recorder using an ALC circuit.

[Problems to be Solved by the Invention] However, when an ALC circuit is used, when a signal shown by a solid line in FIG. 11 is input to this ALC circuit, an output signal level becomes as shown by a dotted line. When the level exceeds the operation level, the sound is attenuated, voices above a certain level are compressed, the dynamic range is reduced, and the original sound cannot be faithfully recorded. In addition, distortion occurs when the attack time is long, and breathing occurs when the recovery time is short.

On the other hand, in order to avoid such problems, according to the method of adjusting the recording level, the compact disc player is set to play before recording, and at the same time, the tape recorder is set to the recording pause and the recording volume is adjusted. It is necessary to stop the compact disk player and the tape recorder later. In addition, for the reasons described above, it is necessary to perform the above-mentioned adjustment over a long period of time for all songs to be recorded. In addition, automatic bias adjustment cannot be performed in parallel with recording level adjustment.

For this reason, the operation becomes extremely complicated and the adjustment time becomes long.

In view of the above problems, an object of the present invention is to perform automatic bias adjustment of a tape recorder and adjust a reproduction signal level of a PCM audio reproduction device in a short time without performing complicated operations, thereby converting an audio analog signal into a magnetic signal. It is an object of the present invention to provide an audio system capable of recording on a tape, recording an original sound more faithfully without narrowing a dynamic range, further reducing distortion and improving an SN ratio.

[Means for Solving the Problems] In the audio system according to the present invention, a PCM audio reproducing device and a reproduction signal level attenuator for attenuating a reproduction signal level of the PCM audio reproducing device by a predetermined amount in response to an attenuation amount switching command S1. In response to the means A and the sampling command S2, a reproduction time of 15 to
A signal level automatic adjusting means comprising: a reproduction signal level sampled for 32 seconds, which is compared with a reference value, and an attenuation control means B for outputting an attenuation switching command S1 when the reproduction signal level exceeds the reference value. An automatic bias adjustment means for automatically adjusting the bias to an optimum bias in response to a bias adjustment command; and a recording sensitivity fixing means for setting a recording sensitivity to a predetermined value in response to a recording sensitivity fixing command, wherein the PCM A tape recorder that records the output of the audio playback device, and a sampling command S2,
An audio system, comprising: a system control unit that outputs a bias adjustment command and a recording sensitivity fixing command and starts recording after the adjustment of the reproduction signal level and the bias is completed.

[Operation] When the recording switch is turned on, an automatic adjustment recording instruction is issued, and the system control unit issues a sampling instruction S2 to the signal level automatic adjustment unit, and issues a bias adjustment instruction and a recording sensitivity fixing instruction to the tape recorder. .

In the signal level automatic adjusting means, the amount of attenuation of the reproduction signal level attenuating means is initially set to a minimum value, and the following operation is performed when a sampling command is received.

That is, when the reproduction signal level exceeds the reference value, the attenuation increases by one step, and the reproduction signal level is suppressed.
If the reproduction signal level further exceeds the reference value in this state, the amount of attenuation is further increased by one step, and the reproduction signal level is suppressed.

When the sampling command is released, the amount of attenuation at this time is fixed.

Therefore, the maximum value of the reproduction signal level becomes a substantially predetermined level, and the reproduction signal level is automatically and appropriately adjusted even if there is a recording level difference for each label or each piece of music in the PCM audio recording medium.

On the other hand, in the tape recorder, the bias adjustment is automatically performed in parallel with this adjustment, and the recording sensitivity is fixed.

Thus, the recording preparation is completed, and then the recording is started.

[Background of the Invention] The present invention was devised based on the following fact analysis results.

The present inventor has recorded music signals other than classical music.
For 120 compact disks, the maximum peak level in the label was detected, and a distribution diagram as shown in FIG. 8 was obtained. In FIG. 8, the horizontal axis represents the maximum peak level in decibels based on the minimum value of the maximum peak level,
It is ranked.

According to this, the recording level difference is large for each label,
Even if the recording volume of the tape deck is set to the center, the problem described in [Prior Art] occurs.
From this figure, it can be seen that it is sufficient to adjust the recording level over a 12 dB width.

Next, how to adjust the reproduction signal level to an optimum value in a short time becomes a problem.

Then, I examined which part of the song has a high probability that the maximum peak level exists in the 120 compact discs.

As a result, a very high probability that there is a maximum peak level before the fade-out end of the song, as shown in FIG. 9, the reproduction time T ₁ before the position from the end of the song and the sampling start position, the time from which T _It was found that sampling only ₂ increases the probability of finding the maximum peak level. It has also been found that even if the maximum peak level is not found in this sampling interval, the maximum peak level in this interval will be approximately equal to the maximum peak level for the entire song.

Then, as a result of performing a statistical analysis by changing T ₁ and T ₂ , to estimate the maximum peak level in a short time and with high probability, set T ₁ to about 60 seconds and T ₂ to about 15 seconds We concluded that we should do it.

Next, when magnetic recording of a plurality of music pieces, how many music pieces need to be sampled in order to estimate the maximum peak level of all the music pieces in a short time and with a high probability becomes a problem.

In order to elucidate this, the present inventors sampled N songs from the first song in the label for the 120 compact discs, and calculated the maximum peak level PLT of all songs in the label from the maximum peak level PLN. The statistical probability P [%] at the time of estimation was obtained. This statistical probability P is expressed by the following equation.

P = 100 · (the number of compact discs whose decibel difference between PLT and PLN is within 3 dB) / 120 A part of the data is shown in FIG. 10, the horizontal axis is the number of sampled songs N, and the vertical axis is The probability P.

In FIG. 10, the lines connected by the dotted line, the one-dot chain line, the two-dot chain line, and the solid line are T ₁ in FIG. 9 as 60 seconds, and T2 as 5 seconds, 10 seconds, 15 seconds and 20 seconds, respectively. Things.

From such a statistical analysis, it was concluded that the number N of sampled songs required and sufficient for estimating the maximum peak level in a short time and with high probability was 3.

[Embodiment] A preferred embodiment of the present invention will be described with reference to the drawings.

<Audio System> FIG. 4 shows a block circuit of an audio system in which a compact disk player 10, an amplifier unit 12, and a tape deck 14 are combined. An analog signal reproduced from the compact disk player 10 is recorded on a magnetic tape. It has become.

The compact disc player 10 includes an optical pickup 16
Is supplied to the servo circuit 18, and the mechanism 20 including the optical pickup 16 is feedback-controlled. Part of the signal from the optical pickup 16 is also supplied to a signal processing circuit 22, where reproduction of a clock pulse, demodulation of an EFM code, error correction and the like are performed, and audio digital data is reproduced. This data is stored in D / A converter 2
4. The original audio analog signal passes through the low-pass filter 26 and is supplied to the signal level automatic adjustment circuit 28.

Here, the microcomputer 30 includes the signal processing circuit 22
Based on a signal supplied from the controller and an operation command supplied via the bidirectional communication line L, various controls of the mechanism 20 are performed, and a sampling command is supplied to the signal level automatic adjustment circuit.

The signal level automatic adjustment circuit 28 receives the sampling command and adjusts the output level of the compact disk player 10 so that the recording input level of the tape deck 14 becomes optimal. During this adjustment, the mechanism
20 is based on a control signal from the microcomputer 30,
For example, the position of one minute before the reproduction time from the end of each song from the first song to the third song recorded on the compact disc is set as the starting point of the sampling, and the analog audio signal level is sampled for 15 seconds each. I have.

The amplifier unit 12 responds to a control signal supplied from the microcomputer 32 and switches the recording input selection circuit 34 so that the audio analog signal (playback sound output signal) from the signal level automatic adjustment circuit 28 is recorded on the tape deck 14. It is designed to supply to the input terminal.

When the CCRS (Computer Controlled Compact Disc Recording System) switch 36 is turned on, the tape deck 14 allows the microcomputer 38 to supply an automatic adjustment recording command to the microcomputers 30 and 32 via the bidirectional communication line L. Has become. Based on this command, the switching operation of the sampling and recording input selection circuit 34 is performed.

A recording sensitivity adjustment resistor 42 and a recording sensitivity fixed resistor 44 are connected in parallel to a recording input terminal of the tape deck 14. The recording sensitivity adjusting resistor 42 and the recording sensitivity fixed resistor 44 are selectively connected to an input terminal of a recording amplifier 46 via a changeover switch 40. When the CCRS switch 36 is turned on, the movable contact of the changeover switch 40 is switched to the recording sensitivity fixed resistor 44 side by the recording sensitivity fixing command from the microcomputer 38, and the recording sensitivity is fixed.

By this switching and the adjustment of the reproduced sound output signal level by the signal level automatic adjustment circuit 28, the audio signal of the optimum level is supplied to the recording amplifier 46.

This audio signal is superimposed with a high-frequency current through a recording amplifier 46 and an AC bias circuit 48, and is supplied to a head 52 constituting a part of a mechanism 50. The AC bias circuit 48 also includes a test tone generator, and supplies a test tone signal to the head 52 while changing a bias current based on a bias adjustment command supplied from the microcomputer 38 when the CCRS switch 36 is turned on. It is supposed to. At this time, the mechanism 50 is driven via the drive circuit 54 based on the control signal from the microcomputer 38, and the recording state is established. After the recording of the test tone, after the magnetic tape is automatically rewound, the test tone is reproduced, and the signal level of the reproduced sound is detected by the output level detection circuit 56 and the microcomputer
Supplied to 38. The microcomputer 38 determines the optimum bias in consideration of the output level, the test tone frequency and the bias current.
The control signal is supplied to and automatic adjustment is performed to obtain the optimum bias.

Since this automatic bias adjustment is performed in addition to the automatic adjustment of the reproduction signal level, without performing a complicated operation,
Furthermore, optimal recording becomes possible.

Such recording by automatic adjustment is hereinafter referred to as CCRS recording, and is distinguished from normal recording by manual adjustment.

Note that the signal level automatic adjustment circuit 28 is
Alternatively, it may be provided on the tape deck 14.

The recording preparation time from when the CCRS switch 36 is turned on until the optimum recording becomes possible is, for example, one minute. After the preparation is completed, the audio signal recorded on the compact disk is recorded on the magnetic tape.

In order to display the operating states of the compact disk player 10, the amplifier unit 12, and the tape deck 14, the microcomputers 30, 32, 38
A display signal is supplied to 31, 35, and 58.

<Operation Indicator> FIG. 5 shows an arrangement of indicators provided on the front panel of the compact disk player 10, the amplifier unit 12, and the tape deck 14.

The display 31 includes a pause indicator 31A, a play indicator 31B, a track number indicator 31C, and a time indicator 31D.
The track number display 31C and the time display 31D are composed of 7-segment LEDs.

In the recording ready state, the pause indicator light 31A is turned on, and "Cd" is displayed on the track number indicator 31C as shown in FIG. In the recording ready state,
When the compact disc player 10 is sampling the audio signal recorded on the compact disc, the “Cd” display flashes. When the recording preparation is completed and the recording state is entered, the pause indicator light 31A is turned off, the play indicator light 31B is lit, and the track number indicator 31C displays the number of the track being reproduced.

The display 35 has a recording output indicator 35A, a recording indicator 35B,
It consists of a recording indicator light 35C.

The recording output indicator light 35A is provided with a bar indicator light at the line connecting the device names shown in FIG. 5, so that the playback signal of any playback device is recorded on either the tape deck A or the tape deck B. Is displayed.
When the bar indicator light is blinking, it indicates that the recording is CCRS recording, and when the bar indicator light is on, it indicates that the normal recording is performed by manual adjustment. For example,
When the playback signal of the compact disc player is recorded on the tape deck B by CCRS, the bar indicator light connecting "CD" and "TAPE B" blinks.

The recording indicator 35B includes indicator lamps a to g arranged in a line. During recording preparation and recording, for example, only the indicator lamp d is lit for a certain period of time first, and then the indicator lamp c, Only e is lit for a fixed time, then only indicator lights b and f are lit for a fixed time, then only indicator lights a and g are lit for a fixed time, and so on. Further, when these are sequentially lit, the recording indicator 35C is also lit.

The indicator 58 is a CCRS indicator 58A, an auto bias indicator 5
8B.

The CCRS indicator 58A blinks during recording preparation and lights up during recording. The auto bias indicator 58B blinks during the bias adjustment, and turns on when the adjustment is completed.

By performing such a display, it is possible to know what operation each device is currently performing.
It is also possible to clearly distinguish between RS recording and normal recording.

<Automatic Signal Level Adjustment Circuit> Next, the automatic signal level adjustment circuit 28 shown in FIG.
This will be described in detail with reference to FIGS.

FIG. 1 is a block circuit diagram of the automatic signal level adjusting circuit 28, and FIGS. 2A and 2B are diagrams of the automatic signal level adjusting circuit 28.
FIG. 3 is a signal waveform diagram of a main part of the automatic signal level adjusting circuit 28 shown in FIG.

As shown in FIG. 1, a reproduction signal level attenuating circuit A, an amplifier 62, and a muting circuit 64 are cascaded, and an output terminal of the muting circuit 64 is connected to an output terminal 65 of the compact disk player 10.

This reproduction signal level attenuating circuit A is a low-pass filter
Buffer amplifier 66 to which audio signal is supplied from 26
And an attenuator 68 following the buffer amplifier 66, and a switch circuit 70 connected to the control terminal of the attenuator 68 and switching the attenuation of the attenuator 68.

The attenuation control circuit B includes a buffer amplifier 72 whose input terminal is connected to an output terminal of the amplifier 62, and a buffer amplifier 72.
The switching signal generation circuit includes a comparator 74 subsequent to 72 and a switching signal generation circuit 76 subsequent to the comparator 74.
The output terminal of 76 is connected to the input terminal of the switch circuit 70,
The control terminals of the comparator 74 and the switching signal generation circuit 76 are connected to the control output terminal of the microcomputer 30.

In the above configuration, the sampling command S2 is supplied from the microcomputer 30 to the comparator 74 and the switching signal generation circuit 76.
Is supplied to the comparator 74, the comparator 74 is activated, the output of the switching signal generation circuit 76 is initialized, and the attenuation of the attenuator 68 is initialized to the minimum value. The signal S3 that has passed through the buffer amplifier 66 is attenuated by the attenuator 68, and then amplified by the amplifier 62.
It is supplied to a comparator 74 and compared with a reference level.
When the output level of the buffer amplifier 72 becomes higher than the reference level, the switching signal generation circuit 76 supplies an attenuation switching command S1 to the switch circuit 70, and the attenuation of the attenuator 68 increases by one step. As a result, the levels of the output signal S4 appearing at the output terminal 65 and the signal input to the buffer amplifier 72 decrease. In addition, sample the playback signal level,
When the comparator 74 determines that the output level of the buffer amplifier 72 is higher than the reference level, the switching signal generation circuit 76 supplies an attenuation switching command S1 to the switch circuit 70, and the attenuation of the attenuator 68 is further increased by one step. You.

By repeating such an operation, even if there is a large recording level difference for each label of the compact disc,
The maximum signal level of the output signal S4 becomes a substantially predetermined value, and an audio signal having a wide dynamic range can be recorded on a magnetic tape without causing distortion and without deteriorating the SN ratio.

2A, the amplifier 62 and the buffer amplifier 66 are non-inverting amplifiers using an operational amplifier, and the buffer amplifier 72 is an inverting amplifier using an operational amplifier. . This amplifier 62 has a de-emphasis control terminal 80 for attenuating the high-frequency portion. The comparator 74 is a Schmitt trigger circuit using an operational amplifier. When the control terminal 82 is set to low level to turn off the transistor 84, the reference voltage increases and the comparison operation is not substantially performed. Further, when the control terminal 82 is set to the high level to turn on the transistor 84, the reference level is reduced to an appropriate value, and the comparison operation is performed.

The switching signal generation circuit 76 includes a quaternary counter using D flip-flops 86 and 88, and counts the number of rising edges of the output voltage of the comparator 74. Also, set the control terminal 90 to low level to set the transistor
When the 92 is turned on, the D flip-flop 88 is set, and after a certain time, the capacitor 94 is charged and the D flip-flop 88 is charged.
The flip-flops 86 and 88 are reset. In this state, the Q output terminals of the D flip-flops 86 and 88 are both at the low level.

The switch circuit 70 includes analog switches 96 and 98, and the attenuator 68 includes resistors 100, 102, 104, 1
06.

In the above configuration, when the control terminal 82 is set to the high level by the microcomputer 30 and the control terminal 90 is set to the low level, that is, when the sampling command is supplied, the signal S5 is set to the low level, and the signal S6 is set to the high level for a certain time. After that, it becomes low level. When the signals S5 and S6 both become low level, the analog switches 96 and 98 are both turned off, and the attenuation of the attenuator 68 becomes a minimum value, for example, +8 dB on the basis of a normal case (the same applies hereinafter).

In this state, an audio signal is supplied to the input terminal of the buffer amplifier 66. When the audio signal level exceeds a predetermined value, the counter of the switching signal generation circuit 76 is counted up and the signal is increased.
S5 becomes high level, the analog switch 96 is turned on, the attenuation of the attenuator 68 increases by one step,
For example, +4 dB. When the output level of the amplifier 62 further exceeds a predetermined value with this attenuation amount, the counter of the switching signal generation circuit 76 is counted up, the signal S5 goes low, the signal S6 goes high, and the analog switch 96
Is turned off, and the analog switch 98 is turned on. As a result, the attenuation of the attenuator 68 is further increased, for example, to 0 dB (this is a normal case). Similarly, in this state, when the output level of the amplifier 62 further exceeds a predetermined value, both the signal S5 and the signal S6 become high level,
The analog switches 96 and 98 are both turned on, and the attenuation of the attenuator 68 is further increased by, for example, -4d
B.

When the normal audio signal is supplied to the input terminal of the buffer amplifier 66, the resistance of the attenuator 68 is selected so that the counter of the switching signal generation circuit 76 is not further counted up.

When the sampling is completed, the control terminal 82 is set to the low level, the control terminal 90 is set to the high level, the comparator 74 becomes inactive, the count value of the switching signal generation circuit 76 is held, and the attenuation of the attenuator 68 is reduced. The quantity is also retained.

Next, another specific circuit of the automatic signal level adjusting circuit 28 will be described with reference to FIG. 2B.

The attenuation control circuit B of the signal level automatic adjustment circuit 28 is a digital circuit, and the audio digital data output from the signal processing circuit 22 shown in FIG. 4 is supplied to a register 120 and a digital comparator 122 and stored in the register 120. If the value of the audio digital data is larger than the value of the audio digital data, the clock pulse output from the signal processing circuit 22 is AND gated in synchronization with the output of the audio digital data.
The register 120 is set through 124, and the value of the register 120 is updated. In this way, the maximum audio digital data during the sampling period is stored in the register 120, and this value D is compared with the reference values E, F, and G (E <F <G) by the digital comparators 126, 128, and 130. The result is code-converted by the code converter 132 and the above-described signals S5 and S6
Is created. These signals S5 and S6 are supplied to control terminals of analog switches 96 and 98 shown in FIG. 2A.

In FIG. 2B, the gate 124 is opened by a sampling command (high-level signal) and a clock pulse.
The register 120 is reset to zero at the rising edge of the sampling command.

It is sufficient that the amount of attenuation is switched in two or more stages. For example, an attenuator is configured using a variable resistor, and at the end of sampling, the variable resistor is driven by a motor in accordance with the value stored in the register 120. May be operated to continuously switch the attenuation amount. In this case, the comparators 126 to 130 are unnecessary, and the rank width, which is the level difference between the reference values E, F, and G, becomes zero.

Further, in the above embodiment, the attenuation control circuit B is configured by hardware, but may be configured by software.

<Procedure for Recording Preparation> Next, a part of the software configuration of the microcomputer 30 and the microcomputer 38 will be described with reference to FIGS. 6 and 7. FIG.

6A and 6B show a recording preparation process. FIG. 6A is a flowchart of the microcomputer 38, and FIG. 6B is a flowchart of the microcomputer 30. FIG. 7 is a flowchart showing details of steps 306 to 314 in FIG. 6 (B).

First, the normally performed processing will be described. When the CCRS switch 36 is turned on in step 200, step 202
Then, it is determined whether the magnetic tape is loaded in the mechanism 50. Normally, the magnetic tape is loaded before the CCRS switch 36 is turned on, and the flow advances to step 204 to transmit the CCRS code to the microcomputer 30. When the microcomputer 30 receives this code, the sixth
The flow shown in FIG.

That is, in step 300, it is determined whether a compact disc is loaded in the mechanism 20. Usually CCRS
It is loaded before the switch 36 is turned on.
Proceed to 2 to transmit the compact disk standby code to the microcomputer 38. On the other hand, the microcomputer 38 proceeds to steps 206, 208 and 210 and receives this compact disk standby code. Here, the compact disk player preparation completion flag FCC and the tape deck bias adjustment completion flag FDB have been reset by an initialization routine when the microcomputer 38 is turned on. So step 21
Proceeding to 1, 212 and 214, the microcomputer 38 supplies a control signal to the drive circuit 54 and the AC bias circuit 48, reads the level of the test tone from the output level detection circuit 56, and performs the automatic adjustment of the AC bias. Next, the process normally proceeds to steps 216 and 220, and returns to step 214. If it is determined in step 220 that the bias adjustment has been completed, the process proceeds to step 221 to set a tape deck bias adjustment completion flag FDB, and then transmits a tape deck standby code to the microcomputer 30 in step 222.

On the other hand, when the power of the microcomputer 30 is turned on, the tape deck preparation completion flag FDC and the compact disk player output signal level adjustment completion flag FCA are reset by the initialization routine, and the microcomputer 30 performs steps 304, 305, and Proceed to 306,
A sampling command is supplied to the signal level automatic adjustment circuit 28 to adjust the output signal level. Then steps 308, 3
Proceeding to step 10, if no tape deck standby code has been received from the microcomputer 38, proceeding to step 314. If the adjustment of the output signal level has not been completed in step 314, the process returns to step 306, and the above processing is repeated.
At this time, when the tape deck standby code is received from the microcomputer 38 in step 310, the flow advances to step 312 to set the tape deck standby flag FDS. When the output signal level adjustment is completed, step 31
The process proceeds from step 4 to step 315, and after the compact disk player output signal level adjustment completion flag FCA is set, the microcomputer 30 transmits a compact disk standby code to the microcomputer 38 in step 316.

On the other hand, the microcomputer 38 normally
Since the process of 218 is not performed, the process proceeds to steps 224 and 226, and waits for reception of the compact disk standby code supplied from the microcomputer 30. When this code is received, the process proceeds to step 228, where the compact disk player ready flag FCC is set, and the compact disk player standby flag FCS is reset. Then, in step 229, the changeover switch is switched to the recording sensitivity fixed resistor 44 side, and then in step 230, recording of the reproduction sound of the compact disk is started.

On the other hand, in the microcomputer 30, since the tape deck standby flag FDS has been set in step 312, the process proceeds to steps 318 and 324, where the tape deck ready flag FDC is set, and the tape deck standby flag FDS is set.
Reset DS. Next, in order to prevent the compact disc from being played before the start of the processing in step 230, the process waits for a predetermined time to elapse in step 326, and
To start playing the compact disc.

Next, if the bias adjustment time of the tape deck 14 is longer than the adjustment time of the output signal level of the compact disk player 10, the microcomputer 38 receives the compact disk standby code from the microcomputer 30 at step 216. In step 218, the compact disc player standby flag FCS is set. Therefore, an affirmative determination is made in step 224, and the process immediately proceeds to steps 228, 229, and 230.

On the other hand, in step 310, since the tape deck standby code is not received, the tape deck standby flag
The FDS has been reset, and a negative determination is made in step 318, and the flow waits for a tape deck standby code to be received in step 320.

Here, the compact disk player preparation completion flag FCC and the compact disk player output signal level adjustment completion flag FCA set in steps 228 and 315 are:
If the compact disc is not replaced, it remains set.For example, if recording is temporarily stopped during recording and the CCRS switch 36 is turned on again, there is no need to perform bias adjustment and output signal level adjustment. No adjustment is made.

That is, an affirmative determination is made in step 212, and the process proceeds to step 222. Further, the processing of step 226 is not performed, and the recording is started immediately. On the other hand, an affirmative determination is also made at step 304, and the routine proceeds to step 330, where the tape deck standby flag FDS is set. Therefore, the process of step 320 is not performed, and the play of the compact disc is immediately resumed. The compact disk player preparation completion flag FCC and the compact disk player signal level adjustment completion flag FCA are reset by a routine (not shown) when the compact disk is replaced.

If only the magnetic tape is replaced during recording without replacing the compact disk, a tape deck ready flag FDC and a tape deck bias adjustment complete flag FDB are similarly set by a routine (not shown). I have.

Next, if no magnetic tape is loaded in the mechanism 50, a negative determination is made in step 202 and the process proceeds to step 234, where the microcomputer 38
Send the deck stop code to 30. On the other hand, the microcomputer 30 converts this into step 308 or step 322.
, The process ends without playing the compact disc. Similarly, if no compact disc is loaded in the mechanism 20, a negative determination is made in step 300 and the process proceeds to step 332, where the microcomputer 30 transmits a compact disc stop code to the microcomputer 38. When the microcomputer 38 receives this in step 208, the recording process ends without performing bias adjustment.

Next, when the power of the compact disc player 10 is turned off or the microcomputer 30 and the microcomputer 38 are not connected by the bidirectional communication line L, the microcomputer 38 receives the compact disc standby code. Since it is not possible, the microcomputer 38 repeats the processing of steps 206 to 210,
After 10 seconds have elapsed in step 206, the recording process ends without performing bias adjustment.

<Automatic Adjustment of Output Signal Level> Next, details of the adjustment of the output signal level (steps 306 to 314) will be described with reference to FIG.

Here, it is assumed that the program number of the compact disk to be recorded on the magnetic tape is set in the compact disk player 10 in advance, and the total number of recorded songs is TK.

 In step 400, the value of N of the Nth music piece is set to 1.

Next, if the value of the total number of recorded songs TK is 3 or more in step 402, the process proceeds to step 404, and the sampling time T _{2 of} one song
15 seconds, and TK as the number of all songs sampled,
Set this value to 3. Next, in step 406, it is determined whether or not the playing time of the Nth music piece is 1 minute or more. If it is 1 minute or more, in step 408, the playing time of 1 minute (T ₁ ) from the start point of the (N + 1) th music piece ) Sampling starts from the previous position. By this sampling, the automatic adjustment of the output signal level is performed by the hardware configuration as described above. Next, the processing of steps 308 to 312 shown in FIG. 6 (B) is performed.
Next, if it is determined in step 416 that T ₂ seconds have not elapsed after the start of sampling and that the track number for which sampling is being performed has not changed in step 418, the flow advances to step 419 to perform sampling. To continue. Next, the process returns to step 308 to repeat the above processing.

If T ₂ seconds have elapsed since the start of sampling or the track number has changed before the elapse of T ₂ seconds, the process proceeds to step 420, where the value of N is incremented. Next, at step 422, the values of N and TK are compared. If N ≦ TK, that is, if the number of sampled songs is two or less, step 40
Return to step 6 and repeat the above process. If N = TK, sampling ends and the process proceeds to step 316.

When recording tracks the number of TK is 2, the process proceeds from step 402 to step 424, is the value of the sampling time T ₂ of the song, for example, 20 seconds. Then, both songs are sampled. Further, when the value of the recording tracks the number TK is 1, the process proceeds from step 402 to step 424,428,430, is the value of the sampling time T ₂ of the song, for example, 32 seconds.

If the total number of recorded songs TK is 0, there is no need to perform sampling, so steps 402 to 424, 428, 432
The microcomputer 30 transmits a compact disc player stop code to the microcomputer 38. When this code is received by the microcomputer 38, the recording is stopped (step 208).

In the above embodiment, the output signal level of the compact disc player 10 is automatically adjusted for all songs to be recorded. However, sampling is performed for each song, and the output signal level is set for each song. May be automatically adjusted.

When the attenuation of the attenuator 68 is set to the maximum during sampling, the sampling time may be shortened by stopping the sampling.

Furthermore, by providing an automatic mode and a manual mode in CCRS recording mode, the T _1, T ₂ is set as described above in automatic mode, a manual mode, according to the type of whether or song take sufficient recording ready time Thus, T ₁ and T ₂ may be set by a setting device. In the manual mode, the number of sampled songs may be set.

[Effect of the Invention] In the audio system according to the present invention, based on the automatic adjustment recording instruction, the system control means issues a sampling instruction S2 to the signal level automatic adjustment means, and also adjusts the bias adjustment instruction and the recording sensitivity to the tape recorder. And the signal level automatic adjustment means
When the playback signal of the audio playback device is sampled for 15 to 32 seconds and the playback signal level exceeds a reference value, the playback signal level is attenuated by a predetermined amount, and this attenuation is set according to the playback signal level. This attenuation is fixed, and the maximum value of the reproduction signal level during sampling becomes substantially a predetermined value. On the other hand, in the tape recorder, automatic bias adjustment is performed in parallel with the above adjustment, and recording sensitivity is reduced. Since the recording level is fixed to a predetermined value, even if there is a recording level difference between labels or songs on the PCM audio recording medium, the reproduction signal level of the PCM audio reproducing apparatus can be shortened without complicated operations. There is an excellent effect that audio analog signals can be appropriately and automatically adjusted in time and recorded on a magnetic tape.

Moreover, this provides an excellent effect that the original sound can be recorded more faithfully without narrowing the dynamic range, and furthermore, the distortion can be reduced and the SN ratio can be improved.

[Brief description of the drawings]

1 to 7 relate to an embodiment of the present invention, FIG. 1 is a block circuit diagram of an automatic recording signal level adjusting device, FIG. 2A is a specific circuit diagram of FIG. 1, and FIG. Another specific circuit diagram of the modification of FIG. 1, FIG. 3 is a signal waveform diagram of a main part of the circuit shown in FIG. 2A, and FIG. 4 is a diagram of an audio system to which the circuit shown in FIG. 1 is applied. FIG. 5 is a block circuit diagram, FIG. 5 is a layout diagram of a display provided on a front panel of each device constituting the audio system, FIG. 6 is a flowchart showing a procedure for recording preparation, and FIG. 7 is a flowchart showing a procedure for sampling. It is. 8 to 10 are diagrams for explaining the background of the present invention, and FIG. 11 is a waveform diagram for explaining characteristics of the ALC circuit. A: Reproduction signal level attenuation circuit B: Attenuation amount control circuit S1: Attenuation amount switching command S2: Sampling command 10: Compact disc player 12: Amplifier unit 14: Tape deck 30, 32, 38 ... Microcomputer 66, 72 Buffer amplifier 68 Attenuator 70 Switch circuit 74 Comparator 76 Switching signal generation circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A PCM audio reproducing apparatus, and reproduction signal level attenuating means A for attenuating a reproduction signal level of the PCM audio reproducing apparatus by a predetermined amount in response to an attenuation amount switching command S1.
In response to the sampling command S2, the reproduction time 15 to 32
A signal level automatic adjusting means, comprising: an attenuation control means B for comparing the reproduced signal level sampled for seconds with a reference value and outputting an attenuation switching command S1 when the reproduced signal level exceeds the reference value. An automatic bias adjustment means for automatically adjusting the bias to an optimum bias in response to a bias adjustment command; and a recording sensitivity fixing means for setting a recording sensitivity to a predetermined value in response to a recording sensitivity fixing command. A tape recorder that records the output of the playback device, and in response to the automatic adjustment recording command, outputs a sampling command S2, a bias adjustment command, and a recording sensitivity fixing command, and starts recording after the adjustment of the reproduction signal level and the bias is completed. An audio system comprising: a system control unit.