JPS62241409A - Preamplifier - Google Patents

Abstract

PURPOSE:To use an input and an output for both an analog and a digital signal by; providing an A/D or D/A converter behind a function switch, selecting a signal after being passed through the A/D or D/A converter or a signal which is not passed, and using one signal as a sound recording output. CONSTITUTION:A switch part A8 decides whether or not the analog or digital signal inputted to an input terminal 6 is passed through the A/D converter part 7. For example, when switching is performed by a switch associated with the function switch 11, it is decided by setting which position of the switch 11 is for analog signal input and which position is for digital signal input. This setting is performed by using the switch associated with the switch 11 as the switch of the switch part A8 as it is. In another way, a relay, an analog switch, and a gate circuit are used for the switch part A8, which is controlled according to the output of the switch associated with the switch 11. Therefore, a device connected to a preamplifier need not be equipped with an A/D converter and a D/A converter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preamplifier whose input and output can be used for both analog or digital signals. Currently, audio equipment is becoming increasingly digital. Typical examples include the compact disc player, V
There is also PCM recording to TR. These devices use analog signals as input and output signals. Therefore, if we consider the case where the output of a compact disc player is recorded in PCM on a VTR, the digital signal is first converted into an analog signal within the compact disc player, and then converted back into a digital signal at the recording stage.

Therefore, distortion in this conversion process is large. In such cases, digital signal output and digital signal input should be used. For this purpose, a preamplifier that can also handle digital signals is required. Of course, the input and output of chainers, cassette deck players, etc. are analog signals, so it must be possible to use analog signals as well. The present invention is a preamplifier for such a purpose.

Next, the present invention will be explained in detail.

In order to input and output digital signals between devices, it is necessary to standardize the format of the digital signals. Currently, PGM based on 16-bit representation is the mainstream, so this method will be taken as an example. Standards regarding synchronization pulses and read clocks are also required. In explaining the present invention, the first
Assume that signals with the data format shown in the figure are input and output. A read clock 3 for reading data is created on the read side using the synchronization pulse 1 as a reference. By doing this, there is always one synchronization pulse for one piece of PCM data, which simplifies the creation of a read clock.

Further, the number of signal lines is one per channel, which is the same as in the case of analog signals, and connectors can be shared. Although this digital signal is a ternary signal, it may be a ternary signal using Ov and the positive voltage side or ov and the negative voltage side. - An example is shown in FIG. 2. FIG. 3 shows a block diagram of the preamplifier of the present invention.

The input to the volume or sound quality adjustment section 10 is a digital signal.

Therefore, it is better to make the volume or sound quality adjustment section 10 digital. Volume adjustment can be performed by a multiplication circuit, and sound quality adjustment can be performed by a digital filter. The output to the output terminal 11 may be output as a digital signal, or may be output as a D/A signal.
It may be converted into an analog signal by a converter and output. Furthermore, in order to operate the volume or tone quality adjustment section 10 in an analog manner, it is necessary to pass the input of the volume or tone quality adjustment section 10 through a D/A converter.

Another configuration diagram is shown in FIG.

In this case, the input to the volume or sound quality adjustment section 20 is an analog signal. Therefore, it is better to make the volume or sound quality adjustment section 20 analog. The output to the output end is the analog signal t.
Alternatively, it may be outputted, or it may be digitized through an A/D converter and output.

In order to perform the volume or sound quality adjustment section 20 digitally, it is necessary to pass the input of the volume or sound quality adjustment section 20 through an A/D converter.

First, the preamplifier shown in FIG. 3 will be explained.0 The input terminal 6 has cases where an analog signal is inputted and cases where a digital signal is inputted thereto.Means for deciding whether to pass the A/D converter section 7 or not. exists. This is done by means of the switching section 8. There are the following means for deciding whether to pass the A/D converter section 7 or not.

(b) Manual switching using a switch placed outside the case.

(b) Switching is performed by a switch linked to function switch 11.

(c) Electrically detects whether an analog signal or digital signal is input and automatically switches.

In (a) above, the switch 8 for the switching section is exposed outside the case, and the switching section A8 uses a relay, analog switch, gate circuit, etc., and is controlled by a switch that is exposed outside the case. There is something to do. In the case of (a), two sets of input terminals may be provided, one for analog and one for digital. An example is shown in Figure 5. Function switch 3
0.31 may be separated or linked. Hereinafter, the switch that determines which input terminal to select from among the input terminals will be referred to as a function switch. This may be a relay or the like. Also, the signal immediately after the function switch is simply expressed as an input signal.

In (b), it is necessary to set which position of the function switch 13 is for analog signal input and which position is for digital signal input. In this setting, the switch linked to the function switch 11 remains in the switching section A8.
In some cases, the switching part A8 is controlled by the output of a relay, analog switch, or gate circuit used in the metal switching part 88 and linked to the function switch 11. FIG. 6 shows an example of a structural diagram of a switch used for the former. An example of the latter case is shown in FIG. Here, the setting section 43 can be set υ1 arbitrarily using jumper wires, switches, printed wiring, etc. In the case of 0 (c), there is a detection circuit that detects whether the input is an analog signal or a digital signal.
9 is connected.

This detection method includes the following methods.

(A) Detect the voltage level.

(B) Take the differentiation of the input signal.

(C) Examine the frequency components of the input signal through a filter.

(A) utilizes the fact that the pulse input has a higher voltage level than the analog signal. In (B), an output appears if the input signal is a pulse. (O has an appropriate cutoff frequency) 1. Detection is performed using an high-pass filter or a low-pass filter. Figure wc9 shows an example of a circuit using the above method. A negative power supply 56 is applied to the input of the comparator 55. Therefore, when synchronization pulse 1 is input, a pulse appears on comparator 55. Nest stabilizing multivibrator 57
As a result, the pulse train of the synchronizing pulses is converted into a direct current, and the relay 59 is driven by the transistor 61. And switching part A60
Switch the relay contact.

Next, the output from the recording terminal 12 to the recording device will be described. This output also has means for switching between analog signal output and digital signal output. This is done by switching section B9. Each position 14, 15° 16 of the switch utilized in the switching section B9 in the WES diagram is used for the purpose shown in Table 1 below.

Table-1 Switch position Input signal Recording terminal signal 14
Analog Digital 15 Analog Analog Digital Digital 16 Digital Analog The switch used in this switching section B9 does not need to be a three-position switch. That is, each combination in Table 1 may have four positions. Also, switching part D23
Another configuration diagram is shown in FIG. The switching means 66, the switching means 67, and the switching means 64 are interlocked. In this method, there is no problem in switching the output to the recording terminal whether the input signal is analog or digital.

There are the following methods for switching the switching section B9.

(a) Manual switching using a switch etc. outside the case.

(b) Set whether to output analog or digital signals for each connected device.

(c) A control signal is received from the device to be connected, and this causes switching.

In (a), there is one in which the switch of the switching section B9 is exposed outside the case, and there is one in which a relay or an analog switch is used in the switching section B9 and the switch is controlled by a switch that is exposed outside the case.

In (b), a switching section (referred to as a setting section here) is provided for each device to be connected, and it is connected to a switch, jumper wire,
Set using printed wiring, etc. An example is shown in FIG.

In (c), there are two methods: a method of providing a control line between the connected device and a method of using a signal line connected to the recording terminal 12 also for control purposes. In the former method, a relay or an analog switch is used for the switching section B9, and it is controlled by input from the control line. There may be only one switching section B9, or there may be one dedicated to each device. The latter method requires some refinement. An embodiment of the portion related to the connection between the preamplifier and the recording device is shown in Fig. 1. signal line 9
0 becomes Ov when there is no signal due to the resistors 91.92 having the same value. The output of the J-7 lip 70 knob 97 indicates whether a digital signal or an analog signal is output to the recording terminal. Now consider the case of digital signal output. NAND circuits 77 and 78 are opened and PCM data 75
is output by transistor 86, and synchronization pulse 76 is output by transistor 123. The synchronizing pulse is detected by the Schmitt trigger circuit 106, and the monostable multivibrator 116 converts the pulse train into DC.

This output 117 indicates that the recording device has a digital signal input. If an analog signal is needed now, the switching request 118 is set to H level for an appropriate time. At this time, the transistor 121 and the transistor 123 try to connect the signal line 90 in the opposite voltage direction. However, since the current limiting circuit 87 is present, the voltage level of the signal line 90 becomes H. Therefore, there is no synchronization pulse.

AND circuit 96 detects that the synchronization pulse is gone,
Flip-flop 97 is inverted to J-.

This causes NAND circuits 77, 78 to close and analog switch 101 to open. In other words, it becomes an analog signal output. Next, consider the case of switching analog signal output to digital signal output. When a positive voltage is input to the switching request 118 for an appropriate time, it is detected by the simulette trigger circuit 93 and J-
The flip-flop 97 is inverted to provide a digital output.

This method requires the above-mentioned modifications to all recording devices. However, general recording devices use analog signal input and are not modified in any way. An example of such a case is shown in FIG.

In this example, if the recording device does not perform any modification, an analog signal is output from the preamplifier. The J-K flip-flop 154 is reset when power is turned on.
6. In this state, analog switch 160 is opened, NAND circuits 129 and 130 are closed, and the output becomes an analog signal. If necessary, the recording device can know that an analog signal is being sent by the absence of a pulse output from the synchronization pulse detection circuit output 183. Now switching to a digital signal pulses the digital request 188. This pulse is detected by the Schmitt trigger circuit 156 and
-K flip-flop 154 is set.

This closes the analog switch 160 and the NAND
Circuits 129, 130 are opened. Therefore, it becomes a digital signal output. However, if this continues, the output will immediately switch back to analog signal output. To prevent this, in the recording device, as soon as the synchronizing pulse is detected by the Schmitt trigger circuit 169, a monostable multivibrator 182 generates a pulse having approximately the same pulse width as the synchronizing pulse, and the transistor 185 sets the signal line 164 to a positive voltage. If the synchronization pulse is not killed by the recording device, this will be detected by the AND circuit 149 and the JK flip-flop 154 will be reset again, resulting in an analog signal output.

Up until now, it has been a preamplifier based on the Wi3 diagram.

Next, consider a preamplifier based on the diagram shown in FIG. The difference between FIG. 3 and FIG. 4 is that the A/D converter section 7 has become the D/A converter section 18, the D/A converter section 13 has become the A/D converter section 22, and therefore the switching section A8 The only difference is the switching position of the switching part C19 and the switching positions of the switching part B9 and the switching part D23. Therefore, the explanation regarding the third factor, the preamplifier, can be applied to FIG. 4 as well as Table 1. Table 2 shows the differences between FIG. 4 and Table 1 in FIG. 3.

Table-2 Switch position Input signal Recording terminal signal 25
Digital Analog 26 Digital Digital Analog Analog 27 Analog Digital Also, since Table-1 has been replaced with Table-2, Figure 10 has changed to Figure IE14. Also, since the switching section A8 has become the switching section C19, it is natural that FIG. 5 changes to that shown in FIG. 15.

Although the above description has been made assuming that the preamplifier is separate from other audio equipment or receiving equipment, the present invention can also be applied as a preamplifier that is integrated with some or all of these devices. Furthermore, it can be applied not only to devices intended only for special audio, but also to devices with other functions added, such as image equipment.

According to the present invention, as described above, it is possible to input digital signals! Digital output is possible, resulting in less distortion. Furthermore, since there is no need to equip each device connected to the preamplifier with an A/D converter or a D/A converter, it also leads to cost reduction.

[Brief explanation of drawings]

FIG. 1 is an example of a PCM signal standard. FIG. 2 shows another example of the PCM signal standard. FIG. 3 is a block diagram of the preamplifier. FIG. 4 is another configuration diagram of the preamplifier. FIG. 5 is a diagram showing input terminals divided into analog and digital input terminals. FIG. 6 is an example of a switch structure diagram. FIG. 8g7 shows an example in which the switching section A is controlled by the setting section. FIG. 8 is a configuration diagram in which the switching section A is controlled by a detection circuit. FIG. 9 is an embodiment of FIG. 8. Fig. 10 is another configuration diagram of the switching unit B9. Fig. 11 is an example of a case where there are multiple recording terminals. Fig. 12 is a circuit when the output of the preamplifier recording terminal is controlled by a recording device. This is an example. FIG. 13 is an example of a circuit according to another method when the output of the preamplifier recording terminal is controlled by the recording device. FIG. 14 is another configuration diagram of the switching section. Figure 5g15 shows a case where the input terminals are divided into analog and digital input terminals. 1 is sync pulse, 2 is PCM data, 3 is read clock, 4 is sync pulse, 5 is PCM data,
6 is an input terminal, 7 is an A/D converter section, 8 is a switching section A, 9 is a switching section B110 is a volume or sound quality adjustment section, 11 is a function switch, 12 is a recording terminal, 13 is a D/A converter section, 14・15 and 16 are switching positions of switching section B, 17 is an input terminal, 18 is a D/A converter section, 19 is a switching section Cl 2O is a volume or sound quality adjustment section, 21 is a function switch 1 22 is an A/D converter section , 23 is the switching section D1, 24 is the recording terminal, 25, 26, 2
7 is the switching position of the switching section, 28 is an analog signal input terminal, 29 is a digital signal input terminal, 30 is a function switch, 31 is a 7-anchor switch, 32 is an A/D converter section, 33 is a switching section A1, 34 is a Goes to the volume or sound quality adjustment section, 35 goes to the switching section B or D/A converter section, Shuttle 36 goes to the moving section, 37 goes to the contact, 38 goes to the A/D converter section, 39 goes to the function switch, 40 goes to the volume or sound quality adjustment section, 41 is the relay power supply, 42 is the switch, 43 is the setting section, 44 is the relay, and 45 is the switching section A1
46 is an input terminal, 47 is a function switch, 48 is an A/D converter section, 49 is a detection circuit, 50 is a switching section A151 goes to the volume or sound quality adjustment section, 52 is an input terminal, 531'17 anntion switch, 54 is the A/D converter part, 55 is the comparator, 56 is the reference power supply, 57 is the monostable multivibrator, 58 is the relay power supply, 59 is the relay, 60 is the relay contact (switching part A), 61 is the transistor, 62 is the volume or Sound quality adjustment section, 63 is an input terminal, 64 is a switching means linked to the switching part A, 65 is an A/D converter part, 66 is a switching part A1, 67 is a switching means linked to the switching part A, 68 is a recording terminal output Switching means for switching to analog or digital signal output, 69 is a recording terminal, 70 is a switching section B171 goes to the volume or sound quality adjustment section, 72 is a recording terminal, 73 is a setting section, 74 is a switching section B
3 signal lines input to , 75 is PCM data, 76
is a synchronization pulse, 77 is a NAND circuit, 78 is a NAND circuit, 79 is a transistor, 80 is a positive power supply, 81
is a negative power supply, 82 is a resistor, 83 is a resistor, 84 is a resistor, 85 is a resistor,
86 is a transistor, 87 is a current limiting circuit,
88 is a positive power supply, 89 is a negative power supply, 90 is a signal line, 91 is a resistor, 92 is a resistor, 93 is a system trigger circuit, 94 is a ground, 95 is a positive power supply, 96 is an AN
D circuit, 97 is a free lag flop on J-, 98 is a resistor, 99 is a capacitor, 100 is a positive power supply, 101 is an analog switch, 102 is an analog amplifier, '103 is a Schmitt trigger circuit, 104 is a ground, 105 is a positive power supply , 106 is a system trigger circuit, 107 is a negative power supply, 108 is a ground, 109 is a resistor, 110 is a transistor, 111 is a negative power supply, 112 is a positive power supply, 113 is a resistor,
114 is a resistor, 115 is a diode, 116 is a monostable multivibrator, 117 is a digital signal input detection output, 118 is a switching request, 119 is an inverter, 120
is a resistor, 121 is a transistor, 122 is a positive power supply, 123 is a transistor, 124 is a digital signal (PCM data), 125 is an analog signal, 126 is a pulse input at power-on, 127 is PCM data, 128 is a synchronization pulse, 129 is a NAND circuit, 130 is a NAND circuit, 131 is a resistor, 132 is a resistor, 133 is a resistor,
134 is a transistor, 135 is a resistor, 13
6 is an analog signal, 137 is a negative power supply, 138 is a positive power supply, 139 is a positive power supply, 140 is a transistor, 141 is a transistor, 142 is a current limit circuit,
143 is a negative power supply, 144 is a positive power supply, 145 is a resistor, 146 is a resistor, 147 is a negative power supply, 148 is an inverter, 149 is an AND circuit, 1
50 is a resistor, 151 is a capacitor, 152 is a positive power supply, 153 is an OR circuit, 154 is a J-K flip-flop, 155 is an AND circuit, 156 is a system trigger circuit, 157 is a positive power supply, 158 is a ground, 159 is a resistor , 160 is an analog switch, 161 is an analog signal, 162 is a capacitor, 163 is an analog amplifier, 164 is a signal line, 165 is a positive power supply, 166
is the Schmitt trigger circuit, 167 is the ground, 168 is the digital signal (PCM data), 169 is the Schmitt trigger circuit, 170 is the ground, -171 is the negative power supply, 172 is the resistor, 173 is the positive power supply, 174 is the resistor, 175 is the transistor, 176 is negative power supply, 177
is a resistor, 178 is a diode, 179 is AN
D circuit, 180 is an inverter, 181 is an analog signal request, 182 is a monostable multivibrator, 183 is a synchronous pulse output, 184 is a positive power supply, 185 is a transistor, 18
6 is a resistor, 187 is a NOR circuit, 188 is a digital request, 189 is an input terminal, 190 is a D/A converter part, 191 is a switching part C, 192 goes to the back volume or sound quality adjustment part, 193 goes to the switching part C 194 is a switching means that is linked to the switching section C; 195 is an A/D converter section; 196 is a switching means that switches the recording terminal to temporary analog or digital signal output; 197 is a recording terminal; 198 is a switching section D1199 is a digital input terminal, 200H function switch, 201 is a function switch, 202 is an analog input terminal, 203 is a D/A converter section, 204 is a switching section C1, 205 goes to the volume or sound quality adjustment section, 206 is a switching section Go to D. 1it@. 1c20゜Sth. ↑ Treasure 40° Treasure 7th. Dou 9 No. 81i. S Shitai? times. @ l Figure 5. 7o. $/l old. The meeting is decided T'3! l+mouth. It's cool.

Claims (12)

[Claims] (1) An A/D converter 7 is provided after the function switch 11 or a means equivalent thereto, and the feature is that the A/D converter 7 is provided with means for selecting whether a signal is passed through the A/D converter 7 or not. preamplifier. (2) There is a D/A converter 18 after the function switch 21 or equivalent means, and the D/A
A preamplifier characterized by comprising means for selecting a signal that has passed through the converter 18 or a signal that has not passed through the converter 18. (3) There is an A/D converter 7 or 22 and a D/A converter 13 or 18 after the function switch, and the signal that does not pass through the A/D converter 7 or 22 and the D/A converter 13 or 18; Claim 1 or claim 1, comprising a switching means for outputting one of the signal after passing through the D converter 7 or 22 and the signal after passing through the D/A converter 13 or 18 as an output for recording. The preamplifier described in Section 2. (4) When there is an analog signal on signal line 90 or 164,
An analog device characterized in that a digital signal output is requested by applying a voltage higher than the analog signal.
Digital switching request method. (5) An output circuit for both analog and digital use, which detects that the voltage on the signal line 90 or 164 is higher than the analog signal that is currently being output, and switches the analog signal output to the digital signal output. (6) An analog-to-digital switching request method characterized by requesting analog signal output by bringing the digital signal or synchronization pulse on the signal line 90 into an abnormal state. (7) A dual-use analog and digital device characterized by detecting that the digital signal or synchronization pulse to be output is different from the data or synchronization pulse on the output signal line 90, and switching the digital signal output to the analog signal output. Output circuit. (8) In data transmission where data is sent in which synchronization pulses and PCM data can be distinguished by voltage, transmission control requires that the receiving side does not continue data transmission or switch to analog signal output by setting the synchronization pulse to an abnormal state. Method. (9) In an output circuit that transmits data in which synchronization pulses and PCM data can be distinguished by voltage, it detects that the synchronization pulses it is outputting are normal on the transmission line, and stops digital signal output or outputs analog signals. An output circuit characterized by switching to an output. (10) In an electrical system where either an analog signal or a digital signal may exist, a detection method characterized by determining whether the signal is an analog signal or a digital signal by detecting the voltage level of the electrical system. . (11) In an electrical system where either an analog signal or a digital signal may exist, detection characterized by determining whether the signal is an analog signal or a digital signal by taking a differential value of the signal of the electrical system. Method. (12) In an electrical system where either an analog signal or a digital signal may exist, detection characterized by determining whether the signal is an analog signal or a digital signal by checking the frequency component of the signal of the electrical system. Method.