KR0136031B1 - Crosstalk improving circuit of switching integrated circuit - Google Patents

Abstract

The present invention provides a switching integrated circuit by providing a crosstalk improving means at an input side to cut off an input signal that is not selected before being applied to the switching integrated circuit when an input signal is simultaneously applied to a plurality of input terminals of the switching integrated circuit. A crosstalk improvement circuit of a switching integrated circuit is provided to prevent crosstalk occurring inside a circuit.

To this end, according to the present invention, the intermediate frequency amplifier 12 amplifies the image intermediate frequency signal tuned by the tuner 11 and outputs the composite image signal, and outputs a plurality of input ports P1 and P1. An output port P3 selectively outputs a composite video signal S1 input to the first port P1 and an external video signal S2 input to the second input port P2 from an external device (not shown). According to the control of the microcomputer 20, the switch further includes a crosstalk improvement circuit unit 40 for automatically blocking a signal not selected by the switching integrated circuit unit 13 at the input side of the switching integrated circuit unit 13. And a buffer circuit portion 40 connected to the output side of the switching integrated circuit portion 13, and a buffer resistor for forming a current path in the buffer circuit portion 14 connected to the output side of the switching integrated circuit portion 13. (R4) is installed and configured more ; The crosstalk improvement circuit unit 40 is disposed between the output side of the intermediate frequency amplifier unit 12 and the first input port P1 of the switching integrated circuit unit 13, and the external image signal input terminal and the switching integrated circuit unit 13. The second input port P2 has a corresponding PNP transistor Q1 and Q2 and resistors R4 and R6 connected in parallel to the collector terminals of the transistors Q1 and Q2, respectively.

Description

Crosstalk Improvement Circuit of Switching Integrated Circuit

1 is a detailed circuit diagram illustrating a crosstalk improving circuit installed at both ends of a switching integrated circuit of a television according to an exemplary embodiment of the present invention.

2 is a view showing a state in which a switching integrated circuit is installed in a conventional television.

* Description of the symbols for the main parts of the drawings *

10 antenna 11: tuner

12: intermediate frequency amplifier 13: switching integrated circuit

14: buffer circuit section 15: image processing section

16: CRT part 20: Micom

40: Crosstalk improvement circuit part Q1-Q3: Transistor

R1 to R6: resistance

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosstalk improvement circuit of a switching integrated circuit. In particular, when the input signal is simultaneously applied to a plurality of input terminals of the switching integrated circuit by providing a crosstalk improving means at an input side of the switching integrated circuit, the switching integrated circuit is integrated. The present invention relates to a crosstalk improvement circuit of a switching integrated circuit configured to block an input signal that is not selected before being applied to the circuit, thereby preventing crosstalk generated inside the switching integrated circuit due to a plurality of signal inputs.

2 shows a state in which a switching integrated circuit is installed in a conventional television. The apparatus of the figure shows the antenna 10 and the channel selection data transmitted from the microcomputer 20 in response to a key input signal from a user. A tuner 11 that tunes to any one of the plurality of channels induced in the antenna 10, an intermediate frequency amplifier 12 that amplifies the image intermediate frequency signal from the tuner 11 and outputs a composite image signal; Switching integrated circuit 13 having one input port P1, P2 and one output port P3 and switched to any one according to the control signal of the microcomputer 20, and the base terminal of the switching terminal R1 through the resistor R1. It is connected to the output port P3 of the switching integrated circuit 13, its collector terminal is connected to the power supply terminal B + through the resistor R3, and its emitter terminal is grounded through the resistor R2. Input from the switching integrated circuit section 13 It consists of a call to a video processor 15, a buffer circuit 14, and, a buffer circuit an image processor 15 for output to the CRT unit 16 and image processing a composite video signal from the (14) such as to transmit to.

Referring to the operation of the television circuit configured as described above, when the user turns on the television by operating the on / off button of the key input unit 30, if a predetermined channel is selected from the key input unit 30, the key input for that According to the signal, the channel data is read from the unillustrated memory in which the microcomputer 20 is integrally formed and transmitted to the tuner 11, and based on this, the tuner 11 is one of a plurality of channels in which the antenna 10 is induced in the antenna 10. Tx and transmits the video intermediate frequency signal to the intermediate frequency amplifier 12. Subsequently, the composite video signal S1 amplified / output by the intermediate frequency amplifier 12 is input to the first input port P1 of the switching integrated circuit unit 13 and the switch and output port P3 therein. After a predetermined buffering operation is performed by the buffer transistor Q1 of the buffer circuit unit 14 through the input, it is input to the image processing unit 15 through the emitter terminal of the buffer transistor Q1 and undergoes a predetermined image processing process. The image is displayed on the screen of the CRT unit 16 as a later image.

At this time, an external video device such as a video cassette recorder (VCR) connected to an external video signal connection terminal (not shown) via a predetermined data transmission cable is turned on by using a separate key input means, and then the video cassette recorder (VCR) is connected. When the TV / video switching button of the television key input unit 30 is selected after the play button is pressed, the switching contact of the switching integrated circuit unit 13 is connected to the second input port P2 according to the control operation of the microcomputer 20. The external image signal S2, which is switched to the PDP and is reproduced from the video cassette recorder VCR (not shown), is input to the second input port P2 of the switching integrated circuit unit 13, and the automatic switching switch therein and After a predetermined buffering operation is performed by the buffer transistor Q1 of the buffer circuit unit 14 via the output port P3, the image processing unit 15 through the emitter terminal of the buffer transistor Q1. Input is being presented on the screen of the CRT display unit 16 as an image after a predetermined image processing.

However, in the television circuit operating as described above, in order to process the external video signal, even if the automatic switching switch of the switching integrated circuit unit 13 is switched to the second input port P2, the composite video signal S1 is set to the first. Crosstalk caused by the two input ports P1 and P2 of the switching integrated circuit unit 13 are physically close to each other since it is continuously applied to the inside of the switching integrated circuit unit 13 via one input port P1. There is a fear that (CROSSTALK) will occur, and the selected signal will receive a brief description of the undesired signal (e.g., a television signal here).

Accordingly, the present invention has been made in view of the above circumstances, and provides a crosstalk improving means at the input side of the switching integrated circuit unit so that when input signals are simultaneously applied to a plurality of input terminals of the switching integrated circuit, it is selected before being applied to the switching integrated circuit. It is an object of the present invention to provide a crosstalk improvement circuit of a switching integrated circuit capable of preventing crosstalk occurring inside the switching integrated circuit by blocking an input signal that is not input.

According to the crosstalk improvement circuit of the switching integrated circuit of the present invention for achieving the above object, an intermediate frequency amplifier amplifies an image intermediate frequency signal tuned and tuned by a tuner and outputs it as a composite image signal, The switch automatically switches according to the control of the microcomputer to selectively output the composite video signal inputted to the first port and the external video signal inputted to the second input port from an external device (not shown). In the video device having a switching integrated circuit portion to be switched, a crosstalk improvement circuit portion for blocking a signal not selected by the switching integrated circuit portion is further configured on the input side of the switching integrated circuit portion, and connected to the output side of the switching integrated circuit portion. The buffer circuit section further includes a pull-up resistor for forming a current path. Property is; The crosstalk improvement circuit portion is a corresponding PNP transistor and a collector of the transistor between an output side of the intermediate frequency amplifier portion and a first input port of the switching integrated circuit portion, and an external image signal input terminal and a second input port of the switching integrated circuit portion. It consists of a resistor connected in parallel to each terminal.

The pull-up resistor R4 is connected to the base terminal of the buffer transistor Q1 of the buffer circuit unit 14 provided between the output port P3 of the switching integrated circuit unit 13 and the input terminal of the image processing unit 15. It is characterized in that it is provided between one side of the resistor R1 and one side of the resistor R3 connected to the collector terminal.

Therefore, according to the present invention configured as described above, when the switching contact of the switching integrated circuit portion 13 is first switched to the first input port (P1) to the base terminal of the transistor Q2 of the crosstalk improvement circuit portion 40 The composite image signal S1 is applied, and accordingly, the battery power source B + from the buffer circuit unit 14 transmits the emitter of the transistor Q2 through the switching integrated circuit unit 13 through the pull-up resistor R4. The transistor Q2 is turned on by forming a current path that is grounded through a terminal and a collector terminal. At this time, the external image signal S2 is connected to the base of the transistor Q3 of the crosstalk improvement circuit unit 40 through an external input terminal. Although the transistor Q3 is not turned on because the switching integrated circuit unit 13 is open when the terminal is applied to the terminal, the external image signal S2 is applied to the switching integrated circuit unit 13. Because the switch integrated circuit 13, the two input ports (P1, P2) are close together physically in that the cross-talk it is not caused (CROSSTALK) is not generated.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a detailed circuit diagram showing a crosstalk improvement circuit installed at both ends of a switching integrated circuit of a television according to an embodiment of the present invention, in which components corresponding to FIG. The detailed description thereof will be omitted.

In FIG. 1, reference numeral 10 denotes an antenna, 11 a tuner, 12 an intermediate frequency amplifier, and 40 a crosstalk improvement circuit unit for preventing crosstalk generated in the switching integrated circuit unit 13 connected to an output side thereof. Is a switching integrated circuit unit whose switching contact is first switched from the first input port P1 to the second input port P2 according to the control of the microcomputer 20, 14 is a buffer circuit unit, 15 is an image processing unit, 16 is The CRT unit 20 is a microcomputer that receives various function key input signals from the key input unit 30 and sends out predetermined control signals to the respective units to control them.

Here, the crosstalk improvement circuit unit 40 is disposed between the output side of the intermediate frequency amplifier unit 12 and the first input port P1 of the switching integrated circuit unit 13, the external image signal input terminal, and the switching integrated circuit unit 13. PNP transistors Q1 and Q2 and resistors R5 and R6 connected in parallel to emitter terminals of the corresponding transistors Q1 and Q2, respectively, between the second input port P2 of One of the resistors R1 and the collector terminal of the buffer circuit unit 14 provided between the output port P3 of the switching integrated circuit unit 13 and the input terminal of the image processing unit 15 connected to the base terminal of the buffer transistor Q1. A pullup resistor R4 is further provided between one of the resistors R3 connected to the pullup resistor.

Next, the operation of the present invention configured as described above will be described in more detail.

That is, when the user first turns on the television by operating the on / off button of the key input unit 30 and selects a predetermined channel from the key input unit 30, the microcomputer 20 is integrated according to the key input signal. The channel data is read from the formed memory (not shown) and transmitted to the tuner 11. Based on this, the tuner 11 tunes to any one of a plurality of channels disposed in the antenna 10 to convert an intermediate image signal into an intermediate frequency. The amplifier 12 is sent to the amplifier 12. Subsequently, the composite image signal S1 amplified / output by the intermediate frequency amplifier 12 is applied to the base terminal of the PNP type transistor Q2 of the crosstalk improvement circuit unit 40, and thus the switching integrated circuit unit 13 The resistor R3 connected to the collector terminal of the NPN transistor Q1 of the buffer circuit portion 14 connected to the output port P3 of the base and the base of the NPN transistor Q1 connected in parallel with the resistor R3. From one side of the pull-up resistor R4 connected to the resistor R1 connected in series to the terminal, a battery power supply B + passes through the switching integrated circuit section 13 via the pull-up resistor R4 and the cross-talk improving circuit portion. The transistor Q2 is turned on by forming a current path that is grounded by the emitter terminal and the collector terminal of the PNP type transistor Q2 of 40.

Accordingly, the composite image signal S1 from the intermediate frequency amplifier 12 applied to the base terminal of the transistor Q2 of the crosstalk improvement circuit unit 40 is connected to the first input port of the switching integrated circuit unit 13. It is inputted to P1 and then output through the internal automatic switching switch and output port P3, and then applied to the base terminal of the NPN transistor Q1 of the buffer circuit section 14 via a resistor R1. As a result, a current path is formed in which the battery power source B + is grounded through the resistor R3 via the collector terminal and the emitter terminal of the transistor Q1, so that the composite image signal S1 is already connected to the transistor Q1. The terminal is output from the terminal and input to the image processor 15.

At this time, when the user presses the play button of an external device such as a video cassette recorder (VCR) (not shown) and then presses the TV / video switching button of the key input unit 30 such as a remote control transmitter of a television, a corresponding key input signal is received. When the microcomputer 20 recognizes and transmits a predetermined control signal C1 to the switching integrated circuit unit 13, the contact point of the switching integrated circuit unit 13 switches to the second input port P2.

Subsequently, an external video signal S2 input through an external input terminal of a television (not shown) is applied to the base terminal of the PNP-type transistor Q3 of the crosstalk improvement circuit portion 40, and thus the switching integrated circuit portion 13 The battery power source B + of the buffer circuit portion 14 connected to the output side is connected to the output port P3 of the switching integrated circuit portion 13 via the pull-up resistor R4, the automatic switching switch and the second input port therein ( The transistor Q3 is turned on by forming a current path that is grounded through the emitter terminal and the collector terminal of the transistor Q3 via P2).

Therefore, the external video signal S2 is an emitter terminal of the PNP transistor Q3, the second input port P2 of the switching circuit unit 13, its automatic switching switch and output port P3, The resistor R1 of the buffer circuit unit 14 is applied to the base terminal of the NPN type transistor Q1. Accordingly, the battery power source B + is connected to the collector terminal of the transistor Q1 via the resistor R3. By forming an emitter terminal and a current path grounded through the resistor R2, the external image signal S2 is output to the emitter terminal of the transistor Q1 and input / processed to the image processor 15. An image from an external device is displayed on the screen of the CRT unit 16.

Therefore, unlike the conventional case, when the external input video signal S2 is processed as described above, the composite video signal S1 from the intermediate frequency amplifier 12 is a PNP type of the crosstalk improvement circuit unit 40. Even when applied to the base terminal of the transistor Q2, since the switching contact of the switching integrated circuit unit 13 is switched to the second input port P2, the battery is applied from the buffer circuit unit 14 toward the first input port P1. Since the power supply B + is cut off, the first input port P1 of the switching integrated circuit unit 13 is not applied, and thus, the external image signal S2 transmitted in the switching integrated circuit unit 13 is not affected. This prevents crosstalk.

On the contrary, in the state where the contact point of the switching integrated circuit unit 13 is switched to the first input port P1 to process the composite image signal S1, the external image signal S2 of the crosstalk improvement circuit unit 40 Even when applied to the base terminal of the PNP type transistor Q3, since the switching contact of the switching integrated circuit unit 13 of the switching integrated circuit unit 13 is switched to the first input port P1, the buffer circuit unit 14 Since the battery power source B + is cut off, it is not applied to the second input port P2 of the switching integrated circuit unit 13 and thus does not affect the composite video signal C1 transmitted in the switching integrated circuit unit 13. This prevents crosstalk.

In the present invention, the crosstalk improvement circuit of the switching integrated circuit has been described using a television as an example. However, the present invention can be easily modified and implemented in other video apparatuses within the scope not departing from the gist of the present invention. Although two input ports of a circuit part were demonstrated, it may be more than that.

Therefore, when an input signal is applied to a plurality of input terminals of the switching integrated circuit at the same time, it prevents crosstalk occurring inside the device of the switching integrated circuit by blocking an input signal that is not selected before being applied to the switching integrated circuit. By doing so, the device function of the switching integrated circuit can be improved.

Claims (2)

The intermediate frequency amplifier 12 amplifies and outputs the image intermediate frequency signal tuned by the tuner 11 as a composite image signal, and outputs it to the plurality of input ports P1 and P2 and one output port P3. The microcomputer 20 to selectively output the composite video signal S1 input to the first port P1 and the external video signal S2 input to the second input port P2 from an external device (not shown). In a video device having a switching integrated circuit section 13, the switch of which is switched automatically according to the control of?, Wherein a signal not selected by the switching integrated circuit section 13 is cut off at the input side of the switching integrated circuit section 13; A crosstalk improving circuit portion 40 is further configured, and a pull-up resistor R4 for forming a current path is further installed and configured in the buffer circuit portion 14 connected to the output side of the switching integrated circuit portion 13; The crosstalk improvement circuit unit 40 is disposed between the output side of the intermediate frequency amplifier unit 12 and the first input port P1 of the switching integrated circuit unit 13, and the external image signal input terminal and the switching integrated circuit unit 13. A switching integrated circuit comprising a corresponding PNP transistor (Q1, Q2) and resistors (R4, R6) connected in parallel to the collector terminals of the transistors (Q1, Q2) between the second input port (P2). Crosstalk improvement circuit The buffer resistor of claim 1, wherein the pull-up resistor R4 is disposed between the output port P3 of the switching integrated circuit 13 and the input terminal of the image processor 15. A crosstalk improvement circuit of a switching integrated circuit, characterized in that it is provided between one side of the resistor (R1) connected to the base terminal and one side of the resistor (R3) connected to the collector terminal.