JPS6355254B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a delay circuit used in television receivers and video tape recorders equipped with an electronic channel selection circuit.

Conventional configuration and its problems FIG. 1 shows a portion of a general soft-touch type electronic tuning circuit. It is composed of an integrated electronic tuning circuit (IC) 39, a volume 29 for obtaining a tuning voltage (BT), a tuning switch 20, a light emitting diode (LED) 26 for displaying the selected channel, and the like.

In FIG. 1, only one of the volume, light emitting diode, switch, etc. provided for several stations is shown, and the other stations are connected to the channel selection circuit 39 in the same way.

Now, when a channel is selected using the channel selection switch 20, one line of the switch 20 is connected to the key-in amount terminal 7 via the resistor 40 and the resistor 5. Previously, when the station of the switch 20 was not selected, the terminal 1 side of the switch 20 had a voltage of 32V, so when the switch 20 was pressed, the terminal 7 went to a high level. When this terminal 7 becomes high level, the tuning circuit 39 starts clock oscillation and shifts the tuning output. That is, the selected channel is shifted until it reaches the station corresponding to the operated switch 20. When the operated station becomes selected, terminal 1 changes from 32V to 0V, terminal 7 changes to low level and oscillation stops, and the operated switch 2 changes from 32V to 0V.
Station 0 is selected.

When remote control is also supported, a reset pulse 4 when a channel is selected by remote control is input to the base of transistor 3, and input from the emitter to key-in terminal 7 via resistor 5. That is, the reset pulse 4 is accepted at a high level and sets the terminal 7 to a high level.
Here, the tuning circuit 39 starts oscillating, and when the position terminal 1 to which the collector of the transistor 3 is connected via the resistor 2 is tuned, the collector becomes a low level and the oscillation stops.

Tuning is performed through this operation, and at the same time as this tuning circuit starts oscillating, the same input as the oscillation output during tuning operation or the pulse input that raises and lowers the channel is sent from the delay terminal 9 of the tuning circuit 39. A pulse is output in width. This pulse has a time delay within the tuning integrated circuit,
Furthermore, the rise time of the defective pulse 18 is slightly delayed from the start of oscillation due to the integration circuit used to convert this pulse into a DC voltage. For this reason, the audio day-to-day operation and LED day-to-day operation using the day-to-day pulse 18 are not sufficient, and noise may occur when switching channels, and the LED may turn on momentarily.

OBJECTS OF THE INVENTION The present invention is intended to eliminate such conventional drawbacks, and an object of the present invention is to provide a defective circuit which outputs a defective pulse at the same time as tuning is started.

Structure of the Invention In the present invention, a day-to-day pulse is created in synchronization with the change in the potential indicating the start of channel selection by the channel selection means, thereby perfecting the audio day-to-day operation and the LED day-to-day operation. be.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, 39 is a soft touch electronic tuning integrated circuit (IC). This IC39
also has terminals other than those shown in the figure, but they are omitted in the figure.

1, 23, and 24 are tuning output terminals, which are connected to one side of the tuning switches 20, 21, and 22. Although there are other terminals corresponding to the number of stations that the IC has, only terminal 1 will be explained here. Terminal 1 is connected to LED 26 for channel selection display via diode 25.
The anode side of the LED 26 is connected to the 12V line 19 via a resistor 38. Further, the terminal 1 is connected to one side of a volume 29 for adjusting the BT voltage. The other side of the volume 29 is connected to a 32V line 36, and the center is connected via a diode 31 to a BT voltage line 37.

Terminal 1 is connected to a common terminal of a band selection switch 32 via a resistor 30, and the other terminals of the band selection switch 32 are connected to a VHF low band terminal 33, a VHF high band terminal 34, and a UHF terminal 35, respectively. connected to the band switching circuit. Terminal 1 is connected to the collector of transistor 3 via resistor 2, and its emitter is connected to the common line side of channel selection switch 20 and to key-in terminal 7 via resistor 5, and capacitor 6 is inserted between the ground. ing. The emitter of the transistor 3 is connected to the base of a transistor 43 via a resistor 41, and a resistor 42 is connected between the base and ground. The collector of the transistor 43 is connected to the base of the defect pulse transistor 15 via a resistor 44.

Terminal 9 is an oscillation output terminal for the daily pulse, and is connected to transistor 1 via resistors 10 and 12.
It is connected to the base of 5. Further, an electrolytic capacitor 11 is connected between the 12V line 19 after passing through the resistor 10 from the terminal 9, and integrates the oscillation output. A resistor 13 is inserted between the base of the transistor 15 and the 12V line 19, and the emitter is 12V.
A diode 14 is inserted between the lines 19, and an electrolytic capacitor 17 is inserted between the lines 19 and ground.
A resistor 16 is provided between the collector and ground, and this collector line is used as an output terminal for each defective pulse signal.

Next, the operation of this circuit will be explained. When terminal 1 is not tuned, 32V is applied to terminal 1, and when it is tuned, it is 0V. That is,
If 32V is applied to terminal 1 when the channel selection switch 20 is operated, the key-in terminal 7 will be at a high level. At this time, the IC 39 starts clock oscillation, and a pulse is output from the defective output terminal 9. Since this pulse has a time delay due to a time delay within the IC circuit and a waveform rounding due to the integration circuit, this defective pulse is an abnormality output due to fluctuations in the tuning voltage BT of the tuning circuit that has already started working. It is not possible to erase sounds etc.

Therefore, in this circuit, the transistor 43 is turned on by the high level voltage generated when the switch 20 selects the terminal 1 position. Therefore, the transistor 15 is also turned on, and the defective pulse 18 becomes high level. By connecting this to subsequent defective transistors, it is possible to configure a defective circuit for audio, LED, AFC circuits, etc.

That is, it is possible to create a daily pulse synchronized with the input pulse to the key-in terminal 7.

Next, when using remote control, when directly selecting a channel using the remote control, a reset pulse is first output, which returns the channel selection position to a certain designated position. Next, pulses indicating how many steps the channel is to be moved are output from another line. This allows you to select the desired channel.

The terminal to which the pulses to be outputted thereafter are inputted is called the channel up terminal 8. That is, a reset pulse is input to the base of the transistor 3, and a pulse indicating how many positions to shift is input to the channel up terminal 8. IC39 is designed to output a defective pulse while a reset pulse is being input and while a channel up pulse is being input, but even when tuning by remote control in this way, the first When the reset pulse is output, the key-in terminal 7 similarly becomes a high level, and the defective pulse is similarly delayed, but according to this circuit, the transistor 3 is activated even in response to the reset pulse.
By turning it ON, it is possible to obtain a defect pulse synchronized with the reset pulse at the collector of the transistor 15.

Effects of the Invention As described above, according to the present invention, when a channel is selected with a channel selection switch and when a channel is selected with a remote control, a potential that changes is detected to start a channel selection operation, and a channel selection operation is also performed. The system is equipped with a tuning means for outputting a pulse from an oscillation output terminal from the start to the end of the tuning, and a delay transistor whose base is connected to the oscillation output terminal via an integrating circuit. In a device that generates a delay pulse, a transistor is provided whose base is connected to the potential change detection point, and the collector output terminal of this transistor is connected to the base of the delay transistor, thereby synchronizing it with the start of tuning. Therefore, it is possible to provide a deadline circuit that can generate a deadline pulse without delay and can prevent audio noise and unnecessary lighting of a display element during channel selection.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a day-to-day circuit including a conventional electronic channel selection circuit, and FIG. 2 is a circuit diagram of a day-to-day circuit according to an embodiment of the present invention. 1, 23, 24...Tuning selection output terminal, 7...Key-in terminal, 39...Tuning selection circuit, 9...Daytime output terminal, 20,21,22...Tuning selection switch, 3, 15, 43... Transistor, 4...Reset pulse signal, 18...Deaf pulse signal.

Claims (1)

[Claims] 1. Starts the tuning operation by detecting the change in potential that changes when the tuning operation is performed by the tuning switch or when the tuning is performed by the remote control, and also starts and ends the tuning operation. Until then, an integrated circuit selection means that outputs pulses from the oscillation output terminal, a defective transistor whose base is connected to the oscillation output terminal via an integrating circuit, and a change in the potential are detected. A first transistor is provided whose output is applied to the base, and the collector output terminal of the first transistor is connected to the base of the default transistor, and when a channel selection operation is performed by the channel selection switch or remote control. A day-to-day circuit characterized in that a day-to-day pulse is obtained from the output terminal of the day-to-day transistor.