JPH018076Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a signal switching circuit suitable for use in signal switching circuits, especially when switching between signal sources with different impedances, such as MM type cartridges and MC type cartridges in record players. Regarding circuits.

BACKGROUND TECHNOLOGY AND PROBLEMS Generally, in an audio system or the like, different cartridges are installed on the player side, for example, an MM type cartridge and an MC type cartridge, and these may be selected and used as necessary. In this case, it is also necessary to switch the equalizer characteristics of the amplifier according to the impedance of the selected cartridge.

However, in the past, such operations were performed manually each time, which resulted in drawbacks such as extremely troublesome handling and complicated operations.

Purpose of the invention In view of these points, this invention has developed a signal switching circuit with excellent operability that can automatically switch signal sources with different impedances as necessary, such as MM type and MC type cartridges. This is what we provide.

Summary of the invention This invention includes a switch circuit for switching between first and second signal sources, first and second switches provided corresponding to the first and second signal sources, and a switch circuit for switching between these switches. a gate circuit for controlling the opening and closing of the switch circuit in response to the opening and closing of the switch; and a time setting means for setting first and second set times in response to the closing of the switch, and an output of the time setting means. energizes the gate circuit to select the first or second signal source during the first set time, and suppresses the output of the selected signal source during the second set time. This makes it possible to automatically select a desired signal source, improve operability, and suppress unpleasant sounds that may occur during selection.

Embodiment Hereinafter, an embodiment of this invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows the circuit configuration of this embodiment. In the figure, 1 and 2 are signal sources, e.g.
MM type cartridge and MC type cartridge, one side of these cartridges 1 and 2 is grounded, and the other side is connected to a common terminal of switches 3 and 4, respectively. Switches 3 and 4 are controlled so that their switching is opposite to each other, as will be described later. And contact a of these switches 3 and 4
The side is connected to the input side of the measuring instrument 5 and is also connected to a reference power source 7 via a resistor 6. Also, contact b
The output side of the amplifier 8 is connected to the output terminal 10 via a muting switch 9. Also, based on the measurement results from the measuring device 5, the control circuit 11 sends the amplifier 8
A control signal is supplied to the amplifier 8 so that the equalizer characteristics of the amplifier 8 are adjusted to match the impedance of the selected one of the cartridges 1 and 2. Note that the measurement results from the measuring device 5 are
2 may be connected to a display device (not shown) for display.

The switches 3 and 4 are automatically switched, and their function is performed by the following circuit configuration. That is, the positive power terminal +
switches 13 and 14, one end of which is connected to B;
The other ends of these switches 13 and 14 are connected to input terminals S and R of a flip-flop circuit 15, respectively. Also, switches 13 and 1
The other end of 4 is connected to each input end of the OR circuit 16,
The output side of this OR circuit 16 is connected to a preset terminal PR of a presettable counter 17. This counter 17 can be preset to a predetermined value, and operates to start (down) counting the clock from the clock circuit 18 in response to a signal supplied from the OR circuit 16.
Further, the counter 17 has a predetermined number of output terminals, for example, output terminals A to D, and the outputs of output terminals C and D among these output terminals vary from 9 to 4 if the value preset to this counter is 9, for example. Up to the value of , the levels are in a mismatched state, but when it becomes 3 or less, it becomes a match state, and when it becomes 0, all terminals are set to low level. counter 1
The output terminals C and D of 7 are connected to respective input terminals of, for example, an exclusive OR circuit 19 as a gate circuit, and the output side of the exclusive OR circuit 19 is connected to an exclusive OR circuit 20 and It is connected to each input terminal of 21. The other input terminal of the exclusive OR circuit 20 is connected to the output terminal Q of the flip-flop circuit 15, while the other input terminal of the exclusive OR circuit 21 is connected to the inverting output terminal of the flip-flop circuit 15. Ru. The output sides of these exclusive OR circuits 20 and 21 are connected to the base sides of transistors 22 and 23, respectively. The emitter of the transistor 22 is grounded, and the collector thereof is connected to a positive power supply terminal +B via a transfer type relay coil 24, for example. Further, the emitter of the transistor 23 is grounded, and its collector is connected to the positive power terminal +B via a transfer type relay coil 25 similar to that described above.
connected to. These coils 24 and 2
5, the above-mentioned switches 3 and 4 are switched in a reverse phase relationship. In other words, transistor 2
When transistor 2 is turned on, the coil 24 is energized and the switch 3 is connected to the contact b side, and the cartridge 1 is ready for use. However, at this time, the transistor 23 is not turned on, so the switch 4 is connected to the contact a side and the cartridge 2 is measured. state. On the other hand, transistor 2
When transistor 3 is turned on, the coil 25 is energized and the switch 4 is connected to the contact b side, making the cartridge 2 ready for use.However, at this time, the transistor 22 is not turned on, so the switch 3 is connected to the contact b side and the cartridge 1 is measured. state. Further, in order to control the muting switch 9, a NOR circuit 26 is provided on the output side of the counter 17.
The output terminals A to D of the counter 17 are connected to each input terminal of the counter 6, and the output side of the NOR circuit 26 is connected to the base of the transistor 27. transistor 2
The emitter of 7 is grounded, and the collector is connected to the coil 28.
It is connected to the positive power supply terminal +B via. When the transistor 27 is turned on, the coil 28 is energized, thereby closing the switch 9, which is in the open state until the normal playing state is entered. In other words, the muting is released. The output side of the NOR circuit 26 is connected to the clock stop terminal CS of the counter 17, so that the counting operation of the counter 17 is stopped at the same time as muting is released.

Furthermore, delay means such as monostable multivibrators 29 and 30 are connected between the NOR circuit 16 and the measuring circuit 5.
are provided, thereby allowing the cartridges 1 and 2 to be measured at any time while the switches 3 and 4 are respectively connected to the contact a side.

Next, the operation of the circuit shown in FIG. 1 will be explained with reference to the signal waveforms shown in FIG. 2. Now, when switch 13 is turned on and switch 14 is turned off at time _T1 , signals _S1 and _S2 as shown in FIG. 2B and C, respectively, are outputted to the output side. A signal _S3 as shown in FIG. 2D is generated on the output side of the OR circuit 6 in synchronization with the signal _S1 . This signal _S3 is the counter 1
7, the counter 17 starts counting down the clock signal from the clock circuit 18 in synchronization with this.
Now, if the preset value of the counter 17 is set to, for example, 9, then the levels of the output terminals C and D of the counter 17 are in a mismatched state with each other.For example, the output level of the output terminal C is a low level, and the output of the output terminal D is a low level. Since the level is high, the output side of the exclusive OR circuit 19 has a second
A high level signal _S4 as shown in Figure E is output. Since the levels of the output terminals C and D of the counter 17 are in a mismatched state until count 4, the output of the exclusive OR circuit 19 is also maintained at a high level until the count position. On the other hand, at this point, the output signal _S5 of the flip-flop circuit 15 is at a high level as shown in FIG. 2F, and the output signal _S6 of the inverting output terminal is at a low level as shown in FIG. 2G. Therefore, the low level signal _S7 is taken out from the output side of the exclusive OR circuit 20 as shown in FIG. High level output signal _S8 as shown in Figure 2
is taken out. As a result, the transistor 23 is made conductive by the signal _S8 , which energizes the coil 25 connected to its collector side, causing the switch 4 to become the contact b side, thereby disconnecting the cartridge 2 from the measurement circuit system. be done. On the other hand, since the output signal _S7 of the exclusive OR circuit 20 is at a low level, the transistor 22 is in an off state, and therefore the switch 3 is maintained in a state connected to the contact a side. That is, the cartridge 1 is connected to the measuring device 5. Therefore, the voltage from the reference power source 7 is divided by the impedance of the cartridge 1 and the resistor 6, and as a result, the impedance information of the cartridge 1 is measured by the measuring device 5.
Note that this measuring device 5 can perform measurement at any time during the first set time period T ₁ to _{T 2} when the signal S ₈ is at a high level, but here, the OR circuit 16 In synchronization with the output signal S ₃ of the monostable multivibrator 29, a
Outputs the output signal S ₁₀ as shown in
S ₁₀ is supplied to the monostable multivibrator 30,
An output signal S ₁₁ as shown in FIG. 2L is taken out and a measurement is made during the duration T of this signal S ₁₁ . Note that the duration of these signals _S10 and _S11 can be set arbitrarily. The measurement result from the measuring device 5 is supplied as a control signal from the control circuit 11 to the amplifier 8, and the amplifier 8 is controlled to have an equalizer characteristic that matches the impedance of the cartridge 1. When the count of the counter 17 becomes 3 or less, the levels of the output terminals C and D of the counter 17 match, and the output signal _S4 of the exclusive OR circuit 19 goes low at time _T2 as shown in FIG. 2E. level, the output signal S ₇ of the exclusive OR circuit ₂₀ becomes high level at time T ₂ as shown in FIG.
As shown in the figure, it becomes low level at time _T2 , and as a result, transistor 23 is turned off, transistor 22 is turned on, transistor 22 is turned on, coil 24 is energized, and switch 3 is turned to contact b side. On the other hand, the coil 25 is deenergized by turning off the transistor 23, and the switch 4 is switched to the contact a side. In other words, this completes the measurement of the cartridge 1. Then, when the count of the counter 17 reaches 0, the outputs of the output terminals A to D both become low level, so that the output side of the NOR circuit 25 is connected to the second set time.
At the end time T3 of _T2 to _{T3 ,} a high level signal _S9 as shown in FIG. 2J is output. This signal _S9 stops the counting operation of the counter 17, and turns on the transistor 27.
When the switch 9 is turned on, the coil 28 is energized and the switch 9 is turned on.
is closed and mutating is released. In other words, by providing a second set time, the device is not put into use immediately after the measurement is completed, but is muted for a while to prevent unpleasant sounds from being output due to unstable operation, and to ensure that the operation is completely stable. After that, mutating is canceled and the device enters the state of use. Therefore, the output side of the output terminal 10 is free from any unpleasant sounds caused by switching operations, etc.
Only the audio information from the cartridge 1 is outputted through the contact b of the switch 3 and the amplifier 8.

Note that in order to obtain the signals S ₄ and S ₉ , the counter 1
7. Clock 18, exclusive OR circuit 1
9 and the NOR circuit 16, two monostable multivibrators may be used.

In this way, in this embodiment, the cartridges 1 and 2 as signal sources can be automatically switched, and the impedance information of the cartridges 1 and 2 is measured by the measuring device 5, and the impedance information of the cartridges 1 and 2 is measured by the amplifier inserted in the signal system. 8 as a control signal, its equalizer characteristics can also be automatically adjusted.

Application Example In the above-mentioned embodiment, this invention was explained using an example of switching between different types of cartridges in a record player, but the present invention is not limited to this, and the invention is also applicable to switching and selecting other signal sources having different impedances. The same applies to cases where

Effects of the invention As described above, according to this invention, a switch circuit for switching between the first and second signal sources, and first and second switches provided corresponding to the first and second signal sources are provided. , a gate circuit for controlling the opening and closing of the switch circuit in response to the opening and closing of these switches, and a time setting means for setting the first and second set times in response to the closing of the switch,
The output of the setting means energizes the gate circuit to select the first or second signal source during the first set time, and the output of the setting means energizes the gate circuit to select the first or second signal source during the second set time. Since the configuration suppresses the output of the selected signal source, the desired signal source can be automatically selected, improving operability.
It is also possible to suppress unpleasant sounds that may occur during selection. Furthermore, there is an advantage that the equalizer characteristics of the amplifier to which the selected signal source is supplied can be automatically switched in accordance with the measurement information of the selected signal source.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of this invention, and FIG. 2 is a diagram to accompany the explanation of the operation of FIG. 1. 1 is an MM type cartridge, 2 is an MC type cartridge, 3 and 4 are switches, 5 is a measuring device, 7 is a reference power supply, 8 is an amplifier, 11 is a control circuit, 15 is a flip-flop circuit, 16 is an OR circuit, and 17 is a preamplifier. A settable counter, 19, 20, and 21 are exclusive OR circuits, 22, 23, and 24 are transistors, 24, 25, and 28 are coils, 26 is a NOR circuit, and 29 and 30 are monostable multivibrators.

Claims (1)

[Scope of utility model registration request] a switch circuit for switching between first and second signal sources; first and second switches provided corresponding to the first and second signal sources; and a switch circuit for switching between the first and second signal sources; A gate circuit for controlling opening and closing, and a time setting means for setting the first and second set times in response to the closing of the switch;
energizes the gate circuit for the set time of
Alternatively, a signal switching circuit characterized in that the second signal source is selected and the output of the selected signal source is suppressed during the second set time.