KR19980039537A - Frequency band filter stage commoning device of television receiver - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency band filter stage sharing apparatus for television receivers, which realizes cost reduction and simplification of production process by sharing input band (BAND) filter circuits of the VHF stage and the UHF stage. A control unit for controlling the operation of the first half and an RF amplifier unit for selecting the broadcast signal of the channel selected by the user from the broadcast signal received by the antenna based on a predetermined control command from the control unit and amplifying to a predetermined level. In the television receiver of the present invention, the RF amplifier unit is configured to change the center frequency to be filtered by the internal switching diode is turned on / off in accordance with a predetermined control signal from the control unit and the tuning voltage applied from the control unit According to the change of its own capacitance To the ground a signal component not related to the frequency signal of the broadcast channel is characterized in that is configured to include a variable capacitance element to the bypass.

Description

Frequency band filter stage commoning device of television receiver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TUNER of a television receiver, and in particular, to share a frequency band filter stage of a television receiver to realize cost reduction and simplification of a production process by sharing an input band (BAND) filter circuit of a VHF stage and a UHF stage. It is about.

Recently, as the functions of a television receiver (hereinafter, referred to as a TV receiver) are gradually diversified and advanced, the user checks the screen state by turning a channel one by one to check a channel where a broadcast signal is received. TV receivers have been developed and distributed to automatically search for broadcast channels in a frequency band.

Fig. 1 is a block diagram showing a schematic configuration of a television receiver having a broadcast channel automatic search function as described above, wherein reference numeral 1 is an antenna for receiving an airwave broadcasting signal, and 2 is received through this antenna 1. An RF amplifier for amplifying the received RF signal, 3 mixes the RF signal from the RF amplifier 2 and the oscillation frequency from the local oscillation circuit 16 to be described later to generate an intermediate frequency signal (IF signal). Is a mixer.

Reference numeral 4 denotes an IF amplifier for amplifying the IF signal output from the mixer 3, and 5 denotes an image intermediate frequency signal PIF and an audio intermediate frequency from the IF signal output from the IF amplifier 4; A P / S separation unit configured to separate a signal SIF, for example, a surface acoustic wave filter, etc., 6 is an audio detector for detecting an audio signal from the SIF signal, and 7 is an image detector for detecting an image signal from the PIF signal. .

Further, reference numeral 8 denotes a remote control unit for selecting a channel desired by the viewer or performing TV / AV mode switching, etc. 9 denotes a receiving unit for converting an infrared signal from the remote control unit 8 into an electric code signal, 10 Denotes a channel memory in which predetermined channel data is stored, and 11 denotes a microprocessor that controls the entire apparatus in accordance with a remote controller signal from the remote controller 8.

Reference numeral 12 denotes a PWM generator for generating a predetermined Pulse Width Modulation (PWM) signal according to the control signal from the microprocessor 11, and 13 denotes an output from the PWM generator 12. An integrated circuit for integrating a PWM signal to generate a predetermined level signal. When the viewer selects a predetermined channel using the remote controller 8, the microprocessor 11 receives channel data corresponding to the channel selected by the viewer. By reading from the channel memory 10 and controlling the PWM generator 12 based on this, a predetermined PWM signal is generated. The PWM signal is then transmitted to the channel selected by the viewer through the integrating circuit 13. It is output as a corresponding voltage control signal.

Subsequently, reference numeral 14 denotes an Automatic Fine Tunning (AFT) circuit provided for precise tuning operation, and 15 denotes a voltage signal applied from the integrating circuit 13 and the AFT circuit 14. 16 is a local oscillation circuit, which generates a predetermined frequency signal according to the level of the voltage signal applied through the adder 15 and outputs it to the mixer 3 to execute a broadcasting station. Done.

On the other hand, the local oscillation circuit 16 is the local oscillation frequency is output in accordance with the change in the ambient temperature or time elapsed, the intermediate oscillation frequency output from the mixer 3 is changed when the local oscillation frequency is changed in this way As a result, stable image reproduction becomes impossible.

The AFT circuit 14 is provided to solve the above problem, which is the variation of the intermediate frequency ( By outputting the voltage signal (± V) for f) to the adder 15, the local oscillation frequency output from the local oscillation circuit 16 is stabilized.

In addition, in the TV receiver, the magnitude of the input signal received through the antenna 1 is changed due to the strength or fluctuation of the reception signal, and reference numeral 17 denotes an image signal detected by the image detector 7. AGC (Automatic Gain Control) for constantly controlling the output level of the image signal from the image detector 7 by controlling the amplification degree of the above-described RF amplifier 2 and IF amplifier 4 based on the level of? Control) circuit.

Although reference numeral 18 is not shown with respect to the audio signal output from the P / S separation unit 5, bass, treble, and volume (in accordance with a control signal from the microprocessor 11) are not shown. A voice processing unit for executing a voice processing such as a volume), and 19 denotes a voice amplifier for amplifying and outputting the voice signal processed by the voice processing unit 18 to the speaker 20.

Reference numeral 21 denotes a color, tint, brightness, etc. according to a control signal from the microprocessor 11 with respect to the image signal output from the P / S separation unit 5. Is an image processing unit which outputs R (Red), G (Green), and B (Blue) signals corresponding to the image signal, and 22 denotes a CRT 23 based on the RGB signal output from the image processing unit 21. CRT driving unit for driving the.

That is, in the device having the above-described configuration, when the viewer executes the broadcasting station through the remote control device 8, the microprocessor 11 drives the PWM generator 12 to control the video and audio of the corresponding channel. Each signal is processed and output through the CRT 23 and the speaker 20. When the user presses an automatic channel search selection key installed in a remote control device or the like as required, the synchronization detection by the synchronization signal detection unit 24 is performed. On the basis of whether the channel is automatically searched for a broadcast signal.

On the other hand, the detailed configuration of the RF amplifier (2) provided in the tuner (TUNER), as shown in Figure 2, RF filter (2a) for screening only the television airwaves from the signal received by the antenna (1) UHF filter 2b for filtering only broadcast signals in the UHF band among the signals selected by the RF filter 2a according to the tuning voltage V _T from the microprocessor 11, and the UHF filter 2b. Only the broadcast signal of the VHF band is filtered out of the signal output from the RF filter 2a according to the first RF amplifier stage 2c for amplifying the signal output from the RF processor and the tuning voltage V _T from the microprocessor 11. It consists of the VHF filter 2d and the 2nd RF amplifier stage 2e which amplifies the signal output from this VHF filter 2d, The conventional RF amplifier part of the above-mentioned structure consists of the microprocessor 11 Diodes D1, D2, and D3 are switched in response to the S1 to S3 switching control signals. / Is the signal of the frequency band to be selected to be tuned as off, and, by controlling the respective band pass filter (2b, 2d) variable capacitance diode that is installed on the internal (VCD1, VCD2) driven by a tuning voltage (V _T) The broadcast signal in the frequency band tuned by the user is selected.

That is, in the conventional RF amplifier 2 having the above-described configuration, at least three lines of the band selection signals S1 to S3 and the tuning voltage V _T from the microprocessor 11 side with respect to the channel selection of the user are provided. Since each filter stage 2b, 2d is provided according to the frequency band of a receiving channel, the structure was also complicated.

The present invention has been made in view of the above circumstances, and the cost reduction and the simplification of the production process are realized by sharing the input band (BAND) filter circuit of the VHF stage and the UHF stage and unifying the control of the tuning voltage (V _T ). It is an object of the present invention to provide a frequency band filter stage sharing apparatus of a television receiver.

1 is a view for explaining a channel tuning process of a conventional television receiver.

FIG. 2 is a circuit diagram showing in more detail the configuration of the RF amplifier 2 shown in FIG.

Figure 3 is a block diagram showing the internal configuration of a frequency band filter stage commonizing apparatus according to an embodiment of the present invention.

******* Explanation of symbols on the main parts of the drawings *******

1: antenna 2,32: RF amplifier

2a: RF filter 2b: UHF filter

2c: first RF amplifier stage 2d: VHF filter

2e: second RF amplifier stage 2f: RF amplifier stage

3: mixer 4: IF amplifier

5: P / S separation unit 6: voice detector

7: Image detector 8: Remote control device

9: Receiver 10: Channel Memory

11: microprocessor 12: PWM generator

13: Integrating Circuit 14: AFT Circuit

15: adder 16: local oscillation circuit

17: AGC circuit 18: voice processing unit

19: voice amplifier 20: speaker

21: image processing unit 22: CRT drive unit

23: CRT (Cathode-Ray Tube) Ⅰ: First filter

II: 2nd filter C1-C9: capacitor

L1 to L8: Inductor D1 to D5: Diode

VCD1 to VCD3: Variable Capacitance Diode

The frequency band filter stage commonizing apparatus of the television receiver according to the present invention for realizing the above object is controlled by the antenna on the basis of a control unit for controlling the operation of the antenna and the entire apparatus for receiving the airwaves and a predetermined control command from the control unit. A television receiver having an RF amplifier which selects a broadcast signal of a channel tuned by a user from a received broadcast signal and amplifies it to a predetermined level, wherein the RF amplifier is internally switched according to a predetermined control signal from the controller. A filter stage configured to change the center frequency to be filtered by the diode being turned on / off, and a signal component irrelevant to the frequency signal of the broadcast channel tuned by the user as its capacitance changes according to the tuning voltage applied from the controller. Variable capacitance bypasses ground to ground And it is characterized in that is configured including a.

That is, according to the present invention having the above configuration, it is possible to select the frequency band of the channel selected by the user by variably setting the frequency characteristics of the band filter united in accordance with a predetermined control signal from the controller.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

FIG. 3 is a block diagram showing a frequency band filter stage commonizing apparatus of a television receiver according to an embodiment of the present invention, in which components that perform the same functions as those shown in FIG. The description will be omitted.

In FIG. 3, reference numeral L6 is an inductor connected to the RF filter 2a in parallel and selects only a broadcast signal of a predetermined frequency or more using a characteristic according to its inductive reactance value, and reference numeral I denotes a capacitor C7. And a first filter in which an inductor L7 and a switching diode D4 are connected in series, the first filter I being turned on according to a predetermined control signal from the microprocessor 11. By driving on / off, the center frequency to be filtered is changed.

Also, reference numeral II is a second filter in which the frequency band of the signal to be filtered is varied according to a predetermined control signal from the microprocessor 11, and the second filter II is a capacitor C8 having a predetermined capacitance value. ) And an inductor L8 and a switching diode D5 connected in parallel to the capacitor C8, and the switching diode D5 is turned on / off in accordance with a predetermined control signal from the microprocessor 11. The center frequency of the signal being filtered while driving is variable.

VCD3 is a variable capacitor for bypassing signal components irrelevant to the frequency signal of the broadcast channel to be tuned to ground as its capacitance changes according to the tuning voltage V _T applied from the microprocessor 11. C9 is a coupling capacitor for cutting off a signal below a predetermined frequency, and 2f is an RF amplifying stage for amplifying a broadcast signal output through the coupling capacitor C9.

Next, the operation of the device having the above configuration will be described.

The broadcast signal received by the antenna 1 is applied to the first filter I through the RF filter 2a. The user operates the remote control device 8, for example, to select one broadcast channel in the UHF band. When tuning, the microprocessor 11 outputs a high level control signal through the S4 and S5 terminals, respectively.

As a result, while the switching diodes D4 and D5 installed in the first and second filters I and II are turned ON, the center frequency of the signal passing through each filter I and II, ) Is changed, and as a result, the UHF broadcast signal of 400 MHz to 800 MHz band is outputted through the two filters I and II.

On the other hand, the microprocessor 11 outputs a predetermined control signal to change the capacitance of the variable capacitance diode (VCD) for UHF band broadcasting channel tuning, thereby bypassing the frequency component unrelated to the broadcasting signal of the tuned channel to ground. Let's go.

As a result, the broadcast signal passing through the coupling capacitor C9 is amplified to a predetermined level by the RF amplifier stage 2f and supplied to the mixer 3, whereby a signal matching the frequency band of the channel tuned by the user is obtained. Selected and supplied.

That is, according to the above embodiment, by sharing the input band (BAND) filter circuits of the VHF stage and the UHF stage, it is possible to realize a frequency band filter stage commonizing apparatus of a television receiver which realizes cost reduction and simplification of the production process.

On the other hand, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the technical gist of the present invention.

As described above, according to the present invention, the input band (BAND) filter circuits of the VHF stage and the UHF stage, which are incorporated in the television receiver tuner, can be shared, thereby reducing cost and simplifying the production process.

Claims (1)

A control unit for controlling the operation of the antenna and the overall apparatus for receiving the airwave broadcasting, and the broadcast signal of the channel selected by the user from the broadcast signal received by the antenna on the basis of a predetermined control command from the control unit and the predetermined In a television receiver equipped with an RF amplifier for amplifying at a level, The RF amplifier is configured to change the center frequency to be filtered by the internal switching diode is turned on / off in accordance with a predetermined control signal from the controller, and its capacitance is changed according to the tuning voltage applied from the controller. And a variable capacitance element for bypassing a signal component irrelevant to a frequency signal of a broadcast channel tuned by a user to ground.