JPS6110388Y2 - - Google Patents

Description

[Detailed description of the invention] The invention is designed so that two different video signals, such as a video signal from a television channel and a video signal reproduced by a video tape recorder (hereinafter referred to as VTR), can be switched and viewed. The present invention is designed to enable particularly good switching operations for monitor television equipment.

An embodiment of the monitor television apparatus of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 indicates a first video signal input terminal to which a video signal from a television channel is supplied, and 2 indicates a second video signal input terminal to which a reproduced video signal from a VTR is supplied. Indicates terminal. The video signal supplied to this first video signal input terminal 1 is supplied to one fixed contact 3a of the changeover switch 3, and this video signal is also supplied to the input side of a signal detection circuit 4 that detects the presence or absence of the video signal. Also, the video signal supplied to the second video signal input terminal 2 is supplied to the other fixed contact 3b of the changeover switch 3, and this video signal is supplied to the signal detection circuit 5 that detects the presence or absence of the video signal. The respective output signals of the equal signal detection circuits 4 and 5 are supplied to a changeover switch control circuit 6. In this case, when there is a detection signal at the output of the signal detection circuit 4, the changeover switch control circuit 6 connects the movable contact 3c of the changeover switch 3 to one fixed contact 3a, and the output of the signal detection circuit 5 detects the detection signal. When there is a signal, the changeover switch control circuit 6 switches the movable contact 3c of the changeover switch 3.
is connected to the other fixed contact 3b. Again 7
indicates a manual switching circuit, and this manual switching circuit 7 is designed so that a desired video signal can be manually selected when a video signal is present at both the first and second video signal input terminals. The movable contact 3c of the changeover switch 3 can be connected to any side by the output signal of the circuit 7. The movable contact 3c of the changeover switch 3 is connected to the video signal input terminal of the monitor television receiver 8. Further, 9 indicates a plug connected to a commercial power source, and this plug 9
The commercial power supplied to the monitor television receiver 8 is supplied to the power supply circuit 10 of the monitor television receiver 8. A switch 11 connects the power obtained to the output side of this power supply circuit 10.
The power supply circuit 1 is supplied to the circuit group 8a, which has a relatively fast start-up, such as a video signal system and an audio signal system, through the power supply circuit 1.
The power obtained on the output side of 0 is supplied to a group of circuits 8b whose rise is relatively slow, such as a heater circuit of a cathode ray tube. In this case, in general, in television receivers, the horizontal pulses obtained from the horizontal output transformer or flyback transformer are rectified and supplied as power to circuits that rise relatively quickly, such as the video signal system. The output side of the oscillator may be grounded via the connection switch 11.
In this case, since the power of the output signal of the horizontal oscillator is relatively small, there is an advantage that a switch with a small capacity can be used.

Further, the movable contact 3c of the changeover switch 3 is connected to the input side of a power supply control circuit 13 via a signal detection circuit 12 that detects the presence or absence of a video signal, and the connection switch 11 is controlled by the output signal of this power supply control circuit 13. When there is a video signal at this movable contact 3c, the connection switch 11 is turned on by the output signal of a power supply control circuit 13, and when there is no video signal at this movable contact 3c, the connection switch 11 is turned off by the power supply control circuit 13.

In FIG. 1, the first video signal input terminal 1
When a video signal is being supplied to the first video signal input terminal, the signal detection circuit 4 detects this video signal and connects the movable contact 3c of the changeover switch 3 to one fixed contact 3a based on this detection signal. 1
The video signal supplied to the monitor television receiver 8 is supplied to the monitor television receiver 8, and a detection signal is obtained at the output side of the signal detection circuit 12, so the connection switch 11 is turned on, and power is also supplied to the circuit group 8a, which has a relatively fast start-up. A reproduced image of the video signal supplied to the first video signal input terminal 1 can be obtained. Further, when a video signal is being supplied to the second video signal input terminal 2, the signal detection circuit 5 detects this video signal and connects the movable contact 3c of the changeover switch 3 to the other fixed contact 3b based on this detection signal. The video signal supplied to the second video signal input terminal 2 is supplied to the monitor television receiver 8, and a detection signal is obtained at the output side of the signal detection circuit 12, so the connection switch 11 is turned on.
Power is also supplied to the circuit group 8a which rises relatively quickly, and a reproduced image of the video signal supplied to the second video signal input terminal 2 can be obtained. Therefore, in FIG. 1, the changeover switch 3 can be automatically switched to the side where the video signal is present. Also the first
When a video signal is supplied to both the second video signal input terminals 1 and 2, the movable contact 3 of the changeover switch 3 is switched to the fixed contact selected by the manual switching circuit 7.
At this time, the video signal of the selected one is supplied to the monitor television receiver 8, and a detection signal is obtained at the output side of the signal detection circuit 12, so the connection switch 11 is turned on, and the comparison Power is also supplied to the circuit group 8a whose target rises quickly, and a reproduced image of the selected video signal can be obtained.

Further, when there is no video signal at both the first and second video signal input terminals 1 and 2, there is no video signal at the movable contact 3c of the changeover switch 3, so no video signal is supplied to the monitor television receiver 8, and the signal is not detected. Since no detection signal is obtained in the circuit 12, the connection switch 11 is turned off, and the power to the circuit group 8a of the monitor television receiver 8, which starts up relatively quickly, is turned off. In this case, for example, if the output side of the horizontal oscillator is grounded, the circuits after the horizontal drive circuit are rendered inoperable. Therefore, unnecessary power loss can be reduced. Also, at this time, only the circuit group 8a that rises relatively quickly is inactive, so when the video signal is supplied to the first or second video signal input terminal 1 or 2 again, the connection switch 11 is turned on and the power is turned off. is supplied, but only the circuit group 8a whose rise is relatively quick is inactive, so that when a video signal is supplied to the first or second video signal input terminal 1 or 2, the monitor television is immediately turned off. A reproduced image can be obtained from the receiver 8, and there is no problem in operation.

Further, FIG. 2 shows a specific example of the main part of the present invention. In this specific example in FIG. 2, the first video signal input terminal 1 is connected to the base of the npn transistor 3d constituting the changeover switch 3,
A collector of the transistor 3d is connected to a power supply terminal 14 to which a positive DC voltage is supplied via a resistor 3e, and an emitter of the transistor 3d is connected to a video signal output terminal 8 connected to an input terminal of a monitor television receiver 8.
In, the second video signal input terminal 2 is connected to the base of an npn transistor 3f constituting the changeover switch 3, and the collector of this transistor 3f is connected to the power supply terminal 14 via a resistor 3g.
The emitter of this transistor 3f is connected to the video signal output terminal 8in. Further, the first and second video signal input terminals 1 and 2 are connected to the input sides of signal detection circuits 4 and 5, respectively, and the output sides of the signal detection circuits 4 and 5 are respectively switched via resistors. NPN transistor 6 forming the switch control circuit 6
a and 6b, the collectors of transistors 6a and 6b are connected to the collectors of transistors 3f and 3d, respectively, and the collectors of transistors 6a and 6b are connected via capacitors 6c and 6d. The emitters of transistors 6a and 6b are also grounded. In this case, when there is a video signal at the first video signal input terminal 1, a positive voltage is obtained on the output side of the signal detection circuit 4, that is, across the capacitor 4a, so the transistor 6a is turned on and the collector of the transistor 3f is grounded. The lever transistor 3f is turned off, and at this time, the transistor 6b is turned off.
is off, so the video signal at the first video signal input terminal 1 is supplied to the video signal output terminal 8in through the transistor 3d. Further, when there is a video signal at the second video signal input terminal 2, the signal detection circuit 5
Since a positive voltage is obtained on the output side of the capacitor 5a, the transistor 6b is turned on, and the collector of the transistor 3d is grounded to turn off the transistor 3d. The video signal supplied to the video signal input terminal 2 of No. 2 is supplied to the video signal output terminal 8in through the transistor 3f. Further, the respective output sides of the signal detection circuits 4 and 5 are connected through respective resistors to the respective bases of the npn type transistors 7a and 7b constituting the manual switching circuit 7, respectively, so that the respective output sides of the transistors 7a and 7b are The emitters are grounded, and the transistors 7a and 7b are
The respective collectors of transistors 7a and 7b are connected to the power supply terminal 14 through resistors 7c and 7d, respectively, and the collectors of transistors 7a and 7b are connected through a series circuit of two resistors 7e and 7f, respectively. The connection point of resistors 7e and 7f is connected to the base of an npn transistor 7g, and this transistor 7g
The emitter of this transistor 7g is grounded, and the collector of this transistor 7g is connected to the power supply terminal 14 via a resistor 7h.
It is connected to the base of an npn type transistor 7i, the emitter of this transistor 7i is grounded, and the collector of this transistor 7i is connected to a movable contact 7ko of a changeover switch 7k which is manually controlled. One fixed contact 7kf of this changeover switch 7k
is connected to the base of transistor 6a, and the other fixed contact 7ks of changeover switch 7k is connected to the base of transistor 6b. In this case, the first
and the second video signal input terminal, when the video signal is supplied to both the first video signal input terminal 1
When you want to see the video signal being supplied to the
Connect to ks. At this time, since transistors 7a and 7b are both turned on, transistor 7g is turned off, so transistor 7i is turned on, and the base of transistor 6b is grounded. The video signal supplied to the first video signal input terminal 1 is supplied to the video signal output terminal 8in through the transistor 3d, and at this time, the signal detection circuit 4 is connected to the base of the transistor 6a.
Since this detection signal is supplied, the transistor 6a is turned on and the transistor 3f is turned off. At this time, if you want to view the video signal supplied to the second video signal input terminal 2, press the switch 7.
Connect the movable contact 7ko of k to one fixed contact 7kf. At this time, the operation is the same as described above, and the transistor 6a is turned off and the transistor 6b is turned on, so the video signal supplied to the second video signal input terminal 2 is supplied to the video signal output terminal 8in through the transistor 3f. Further, when there is a video signal at only one of the first or second video signal input terminals 1 or 2, a predetermined voltage is supplied to the base of the transistor 7g by resistors 7e, 7f, etc.
Since this transistor 7g is turned on, the transistor 7i is turned off, and the switching position of the changeover switch 7k has no bearing on the operation. Also, the video signal output terminal 8in is connected to the base of an npn transistor 13a constituting the power supply control circuit 13 via the signal detection circuit 12, the emitter of this transistor 13a is grounded, and the collector of this transistor 13a is connected via a resistor. configuring the connection switch 11
A DC power input terminal 10a is connected to the base of a type transistor 11a, and a DC power input terminal 10a connected to the output side of the power supply circuit 10 is derived from the emitter of this transistor 11a. Output terminal 8c connected to the power supply terminal of circuit group 8a with a fast
Derive. In this case, when there is a video signal supplied to the video signal output terminal 8in, the signal detection circuit 12
A detection signal is obtained on the output side of transistor 13.
A is turned on, the transistor 11a is turned on, and power is supplied to the circuit group 8a, which has a relatively fast rise.
When this detection signal is not present, the transistor 13a
and 11a are both turned off, and power is not supplied to the circuit group 8a, which rises relatively quickly.

In the above embodiment, the video signal output terminal 8
Although it has been described that the power supply control circuit 13 is controlled by detecting the video signal of the in, it is easily possible to control the power supply control circuit 13 by the output signals of the signal detection circuits 4 and 5 instead. I can understand.

Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations may be adopted without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the monitor television apparatus of the present invention, and FIG. 2 is a connection diagram showing a specific example of the main parts of the present invention. 1 and 2 are video signal input terminals, 3 is a changeover switch, 4, 5 and 12 are signal detection circuits, and 6
is a changeover switch control circuit, 8 is a monitor television receiver, 8a is a group of circuits that start up relatively quickly,
Reference numeral 8b indicates a group of circuits that start up relatively slowly, 10 indicates a power supply circuit, and 11 indicates a connection switch.

Claims (1)

[Scope of utility model registration request] a first television signal input terminal to which a first television signal is supplied; a second television signal input terminal to which a second television signal is supplied; a television receiver; a changeover switch having a television signal input terminal connected to one fixed contact, the second television signal input terminal connected to the other fixed contact, and a movable contact connected to the input side of the television receiver; First and second television signal detection circuits detecting the presence or absence of the first and second television signals, respectively, and output signals of the first and second television signals are supplied to the changeover switch. a switch control circuit for switching and controlling the movable contacts; and a manual switching circuit to which the output signals of the first and second television signal detection circuits are supplied, and a manual changeover switch for controlling the movable contacts of the changeover switch; The movable contact of the changeover switch is switched to the side where the television signal is present by the detection signals of the first and second television signal detection circuits, and the first and second television signals are both If the desired first or second television signal is present, the desired first or second television signal is selected by the changeover switch of the manual changeover circuit, and if both the first and second television signals are not present, the television reception is selected. A monitor television device characterized in that power is not supplied to a circuit that starts up relatively quickly.