KR100247832B1 - A high frequency electronic device - Google Patents

Abstract

The present invention is intended to improve the image quality by suppressing the level of the disturbance signal generated by the oscillation signal of the modulator and the oscillation signal of the tuner when the modulator and the tuner are operated simultaneously.

In the present invention, the frequency converter converts the modulation unit 4 having the oscillator 10, the high frequency unit 14 for selectively receiving and outputting a television signal, and the selected television signal output from the high frequency unit 14. And a tuner section 5 having a mixer 15 and a local oscillator 16 for inputting a local oscillation signal to the mixer 15, wherein the high frequency section 14 sends the selected television signal to the mixer 15. A low pass filter 19 connected between the single pass tuning circuit 25 and the mixer 15, the low pass filter 19 being connected between the single pass tuning circuit 25 and the mixer 15; Cut-off frequency) is set higher than the highest frequency among the television signals received by the high frequency unit 14.

Description

High frequency electronics

The present invention relates to a high frequency electronic device comprising a modulator and a tuner in one metal box.

In recent video tape recorders (hereinafter referred to as VTRs), high-frequency electronic devices in which a modulator and a tuner are formed in one metal box are used.

4 is a block diagram illustrating such a conventional high frequency electronic device. In FIG. 4, the high frequency electronic device 41 includes a modulator 44 and a tuner 45 assembled on a printed wiring board 43 housed in one metal box 42. The modulator 44 has a divider 46, a mixer 47, a modulator 48, a PLL circuit 49, and the like, while the tuner 45 includes a VHF high frequency unit 50 and a VHF mixer ( 51), a VHF local oscillator 52, a UHF high frequency part 53, a UHF mixer 54, a UHF local oscillator 55, an intermediate frequency amplifier 56, and the like.

The metal box 42 is provided with an input terminal 57 and an output terminal 58, and the modulator 44 and the tuner 45 are shielded plates 59 connected to the metal box 42. Are shielded from each other by

The television signal input to the input terminal 57 is input to the television receiver, not shown, from the output terminal 58 via the distributor 46 and the mixer 47, and the television signal distributed by the distributor 46. Is input to the VHF high frequency section 50 and the UHF high frequency section 53 of the tuner section 45.

In addition, the PLL circuit 49 of the modulator 44 is provided with a voltage controlled oscillator (hereinafter referred to as a VCO) for outputting a carrier signal, not shown, and the VC0 is reproduced by a video signal reproduced by a VTR, not shown. The carrier signal from the modulator 48 is modulated by the modulator 48 and input to the television receiver, not shown, via the mixer 47 and the output terminal 58 as a television signal. Thus, the frequency of the carrier signal from VC0 is controlled by the PLL circuit 49 to match the frequency of the predetermined video carrier signal that the television receiver can receive, but this frequency is generally the region where the VTR is used. Is set to the frequency of the channel not being used for broadcasting.

On the other hand, the VHF high frequency section 50 in the tuner section 45 selects the television signal of the desired channel from among the VHF band television signals, and similarly, the UHF high frequency section 53 sets the television of the desired channel among the UHF band television signals. As a signal is selected, although not shown in the drawing, each has an input tuning circuit comprising a single tuning circuit, a high frequency amplifier, and an inter-step tuning circuit consisting of a double tuning circuit. Then, the television signal of the selected channel is input to each of the VHF mixer 51 and the UHF mixer 54 in each inter-stage tuning circuit, and the local oscillation signal from the VHF local oscillator 52 and the UHF local oscillator 55 By mixing, the frequency is converted into an intermediate frequency signal, and is input to the circuit of a later stage not shown through the intermediate frequency amplifier 56.

However, in the state where the conventional high-frequency electronic device is assembled to the VTR, the power supply voltage is always applied to the modulator 44 and the tuner 45 regardless of the recording or reproduction of the VTR. Therefore, although the modulator 44 and the tuner 45 are shielded from each other in the shield plate 49, the oscillation signal (carrier signal) from the VCO of the PLL circuit 49 in the modulator 44 Harmonics easily fly into the VHF high frequency section 50 or the UHF high frequency section 53 of the tuner section 45. Then, the flying harmonics are input to the respective VHF mixers 51 and UHF mixers 54 through the VHF high frequency unit 50 or the UHF high frequency unit 53, and to the VHF mixers 51 or the UHF mixers 54. By mixing with the harmonics of the local oscillation signal from the VHF local oscillator 52 or the UHF local oscillator 55, a problem arises in that an interference signal of a frequency very close to the frequency of the intermediate frequency signal is generated.

An example of the above problem is that a conventional high frequency electronic device is used for a VTR of European specification such as Germany in which the output channel is set to channel 32 (that is, the carrier signal from the VCO of the modulator 44 is set to the frequency of channel 32), Furthermore, the case where channel 26 is recorded will be described.

In this case, channel 26 of the European television system corresponds to the UHF band, and the UHF local oscillator 55 of the tuner section 45 of the high frequency electronic device 41 outputs a local oscillation signal of 550.15 MHz. On the other hand, since the output channel of the VTR is set to channel 32, the VCO of the PLL circuit 49 of the modulator 44 oscillates at 559.25 MHz. These two oscillation signals are input to the UHF mixer 54, and their harmonics are also input.

The frequency of the difference between the fourth harmonic (2237 MHz) of the oscillation signal of the VCO and the fourth harmonic (2200.6 MHz) of the oscillation signal of the UHF local oscillator 55 is 36.4 MHz. This frequency (36.4 MHz) falls between the video intermediate frequency (38.9 MHz) and the audio intermediate frequency (33.4 MHz) in a European television system, which is a disturbing signal for the normal reception channel 26. As a result, the picture quality of the recorded television signal was deteriorated.

Based on the above relationship, for example, when the output channel of the VTR is set to channel 63 when the reception channel is channel 26, the output channel of the VTR is channel 44 or channel 45 when the reception channel is channel 38. When set, or when the output channel of the VTR is set to channel 22 or channel 52 when the receiving channel is channel 46, etc., it is generated by many combinations.

Therefore, the high frequency electronic device of the present invention improves the image quality by suppressing the level of the disturbance signal generated by the oscillation signal of the modulation section and the oscillation signal of the tuner section when the modulation section and the tuner section operate simultaneously. .

1 is a block diagram of a high frequency electronic device of the present invention;

2 is a circuit diagram of a low pass filter used in the high frequency electronic device of the present invention;

3 is an explanatory diagram illustrating a method of forming a capacitor of a low pass filter used in the high frequency electronic device of the present invention;

Figure 4 is a block diagram of a conventional high frequency electronic device.

※ Explanation of symbols for main parts of drawing

1: high frequency electronic device 2: metal box body

3: printed wiring board 4: modulator

5: tuner part 6: distributor

7 mixer 8 modulator

9: PLL circuit 10: VCO

11: VHF high frequency part 12: VHF mixer

13: VHF local oscillator 14: UHF high frequency part

15: UHF Mixer 16: UHF Local Oscillator

17: intermediate frequency amplifier 18: first low pass filter

19: second low pass filter 20: VHF input tuning circuit

21: VHF high frequency amplifier 22: VHF inter-stage tuning circuit

23: UHF input tuning circuit 24: UHF high frequency amplifier

25 UHF inter-stage tuning circuit 26 First inductance element

27: first capacitor 28: second capacitor

29: second inductance element 30: third capacitor

31: fourth capacitor 32: input terminal

33: output terminal 34: shield plate

35: L type low pass filter 36: coil

37: capacitor 38, 39: conductor pattern (conductive pattern)

40: floating capacity

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the high frequency electronic device of this invention is a metal box body, the printed wiring board accommodated in the said metal box body, the modulation part comprised on the said printed wiring board, and an oscillator, and the said printed wiring A tuner portion which is formed on a substrate and has a high frequency portion for selectively receiving and outputting a television signal, a mixer for frequency converting the selected television signal output from the high frequency portion, and a local oscillator for supplying a local oscillation signal to the mixer; And the high frequency section has an end-to-end tuning circuit for inputting the selected television signal to the mixer, and connects a low pass filter between the end-to-end tuning circuit and the mixer and sets the cutoff frequency of the low pass filter to the high frequency. Higher than the highest frequency in the television signal It was.

In addition, the high-frequency electronic device of the present invention, the high-frequency unit has a UHF high-frequency unit that selectively receives and outputs a television signal of the UHF band, the mixer UHF frequency-converts the selected UHF band television signal output from the UHF high-frequency unit A local oscillator having a mixer, and having a UHF local oscillator for supplying a local oscillation signal to the UHF mixer, and having a UHF inter-stage tuning circuit for inputting the selected UHF band television signal to the UHF mixer; The low pass filter was connected between at least the UHF end-to-end tuning circuit and the UHF mixer.

Moreover, the high frequency electronic device of this invention comprised the said low band pass filter with the L type low band pass filter which consists of an inductance element and the capacitance element connected between one end of the said inductance element, and ground.

In addition, the high-frequency electronic device of the present invention is a low-pass filter, the inductance element and the capacitor connected in parallel with each other, the inductance element and the capacitor connected to one end of the capacitor and the ground connected in parallel to each other connected to ground. It consists of the low pass filter of the induction M type | mold which consists of these.

Moreover, the high frequency electronic device of this invention formed the said capacitor | capacitance with the stray capacitance comprised between two conductor patterns (conductive patterns) provided on the said printed wiring board.

Hereinafter, the high frequency electronic device of the present invention will be described with reference to FIGS. 1 to 3. First, Figure 1 shows a block diagram of a high-frequency electronic device of the present invention, the high-frequency electronic device 1 is a modulator 4 and the tuner on the printed wiring board 3 accommodated in one metal box body (2) The part 5 is assembled and comprised. The modulator 4 includes a divider 6, a mixer 7, a modulator 8, a PLL circuit 9, and the like, and the PLL circuit 9 is a voltage controlled oscillator which is an oscillator for generating a carrier signal. 10 (hereinafter referred to as VC0).

On the other hand, the tuner unit 5 frequency-converts the television signals output from the VHF high frequency unit 11 and the VHF high frequency unit 11, which are the high frequency units that select and output the VHF band television signals received from the VHF band television signals. The UHF band television signal received from among the VHF mixer 12, which is a mixer for outputting the intermediate frequency signal, the VHF local oscillator 13, which is a local oscillator, which supplies the local oscillation signal to the VHF mixer 12, and the UHF band television signal are selected. Local oscillation to UHF mixer 15 and UHF mixer 15, which are mixers which frequency convert UHF band television signals output from UHF high frequency unit 14 and UHF high frequency unit 14 to output intermediate frequency signals And an intermediate frequency amplifier 17 for amplifying the intermediate frequency signal from the UHF local oscillator 16, the VHF mixer 12, or the UHF mixer 15, which is a local oscillator for supplying signals. .

The VHF high frequency section 11 and the UHF high frequency section 14 each have an input tuning circuit, a high frequency amplifier, an inter-step tuning circuit, and the like, and between the VHF high frequency section 11 and the VHF mixer 12 and the UHF. Between the high frequency part 14 and the UHF mixer 15, the 1st low pass filter 18 and the 2nd low pass filter 19 are provided, respectively.

Here, the VHF high frequency part 11 is comprised by connecting the VHF input tuning circuit 20, the VHF high frequency amplifier 21, and the VHF inter-step tuning circuit 22 one by one, and the UHF high frequency part 14 The UHF input tuning circuit 23, the UHF high frequency amplifier 24, and the UHF end-to-end tuning circuit 25 are connected in order. The first low pass filter 18 is connected to the VHF end-to-end tuning circuit 22 of the VHF high frequency part 11 and the VHF mixer 12, and the second low pass filter 19 is connected to the UHF high frequency part. The UHF inter-step tuning circuit 25 and the UHF mixer 15 are connected.

The first low pass filter 18 is composed of an inductive M-type filter, and includes a first inductance element 26 and a first capacitor 27 connected in parallel to each other, a first inductance element 26 and a first connection in parallel. The first capacitor 27 has a second capacitor 27 which is a capacitor connected between one end of the first capacitor 27 and the ground. Similarly, the second low pass filter 19 is also composed of an inductive M-type filter, and the second inductance element 29 and the third capacitor 30 connected in parallel with each other, and the second inductance element 29 connected in parallel with each other. ) And a fourth capacitor 31 which is a capacitor connected between one end of the third capacitor 30 and ground.

The first low pass filter 18 passes up to a television signal of the highest frequency (230 MHz in a European television system) of the VHF band television signals received by the VHF high frequency unit 11, and has a frequency higher than the highest frequency. The cutoff frequency is set, for example, between 1000 MHz and 1500 MHz so as to attenuate the signal, and the second low pass filter 19 is the highest frequency of the UHF band television signals received by the UHF high frequency section 14 (in European television systems). The cut-off frequency is set, for example, between 1500 MHz and 2000 MHz so as to attenuate signals of frequencies higher than the highest frequency passing through the television signal up to 862 MHz).

For this reason, even if the input of a signal having a cutoff frequency of about 1000 MHz to 15000 MHz or more is blocked or input to the VHF mixer 12, the level of the signal is suppressed low. Similarly, the UVHF mixer 15 has a temperature of about 1500 MHz to 2000 MHz or more. Even if the input of the signal of the frequency is blocked or input, the level of the signal is suppressed low.

In addition, an input terminal 32 and an output terminal 33 are provided in the metal box 2 of the high-frequency electronic device 1 of the present invention, and the modulator 4 and the tuner 5 are made of a metal box. They are shielded from each other by the shield plate 34 connected to (2).

The television signal input to the input terminal 32 is input from the output terminal 33 to the television receiver not shown through the distributor 6 and the mixer 7, and can be viewed with this television receiver. On the other hand, the television signal distributed by the distributor 6 is input to the VHF high frequency part 11 and the UHF high frequency part 14 of the tuner part 5. In addition, the oscillation signal output from the VCO 10 of the PLL circuit 9 in the modulator 4 is used as a carrier signal, and the carrier signal is shown in the omitted VTR in which the high frequency electronic device 1 is assembled. Modulated by the modulator 8 by the reproduced video signal, etc., and input to the television receiver, not shown, via the mixer 7 and the output terminal 33 as a television signal.

Therefore, the frequency of the carrier signal from the VCO 10 matches the frequency of the predetermined video carrier signal corresponding to the channel determined by the television system so that it can be received by the television receiver. Therefore, the VCO 10 is PLL controlled. The frequency of this carrier signal is generally set to the frequency of the channel not being used for broadcasting in the region where the VTR is used, and this frequency can be set to the frequency of any channel by the PLL circuit 9.

On the other hand, the VHF high frequency section 11 of the tuner section 5 selects a television signal of a desired channel from among the VHF band television signals, and similarly, the UHF high frequency section 14 selects a television signal of a desired channel from the UHF band television signals. By selecting, the selected VHF band television signal is output from the VHF inter-stage tuning circuit 22 and input to the VHF mixer 12 via the first low pass filter 18. Similarly, the television signal of the UHF band selected by the UHF high frequency unit 14 is output from the UHF interstage tuning circuit 25 and input to the UHF mixer 15 via the second low pass filter 19.

Here, as described above, the first low pass filter 18 has its cutoff frequency set to a frequency higher than the highest frequency in the VHF band television signal received by the VHF high frequency unit 11 (for example, 1500 MHz). The VHF mixer 12 has a low level even when the input of harmonics of 1500 MHz or more from the VCO 10 of the PLL circuit 9 of the modulator 4 is blocked or input. Since the cutoff frequency is set to a frequency higher than the highest frequency among the UHF band television signals received by the UHF high frequency unit 14 (for example, 2000 MHz), the UHF mixer 15 has a PLL circuit of the modulator 4. Even if the input of harmonics of 2000 MHz or more from the VCO 10 in (9) is blocked or input, the level is suppressed low.

Then, the VHF band television signal input to the VHF mixer 12 is mixed with the local oscillation signal from the VHF local oscillator 13 in the VHF mixer 12 to be frequency converted into an intermediate frequency signal, and the intermediate frequency output is intermediate. The UHF band television signal inputted to the circuit of the latter stage shown in the figure after passing through the frequency amplifier 17 is similarly carried out by the local oscillation signal from the UHF local oscillator 16 in the UHF mixer 15. By mixing with, the frequency is converted into an intermediate frequency signal, and the intermediate frequency output is input to the circuit of the later stage, not shown, via the intermediate frequency amplifier 17. At the rear end of the intermediate frequency amplifier 17, a video demodulator and the like (not shown) are provided, and the video signal demodulated by the video demodulator is recorded.

As described above, in the high frequency electronic device of the present invention, the first low pass filter 18 is provided between the VHF inter-step tuning circuit 22 of the VHF high frequency part 11 and the VHF mixer 12, and Since the second low pass filter 19 is provided between the UHF inter-step tuning circuit 25 of the UHF high frequency section 14 and the UHF mixer 15, the PLL circuit 9 of the modulator 4 Harmonics of the oscillation signal from the VCO 10 are less likely to be input to the VHF mixer 12 and the UHF mixer 15, so that the level of the disturbance signal generated in the VHF mixer 12 and the UHF mixer 15 is suppressed very low. can do.

In this case, when the harmonics from the VHF local oscillator 13, which mixes with the harmonics of the oscillation signal of the VCO 10 and generates the interference signal, are compared with the harmonics from the UHF local oscillator 16, the UHF local oscillator 16 Since the order of harmonics is lower, the level of harmonics from the UHF local oscillator 16 is higher (generally, the level of harmonics is higher as the order is lower). Therefore, the interference signal is remarkably output from the UHF mixer 15 rather than the VHF mixer 12. Therefore, the generation of the interference signal can be effectively prevented by providing the second low pass filter 19 between at least the UHF inter-step tuning circuit 25 of the UHF high frequency section 14 and the UHF mixer 15.

The circuit configurations of the first low pass filter 18 and the second low pass filter 19 are not limited to the low pass of the inductive M type as shown in FIG. The L-type low pass filter 35 shown in Fig. 2 configured in the positive K-type filter or the half section of the positive K-type filter may be used. The low pass filter 35 can be simply composed of two components: an inductance element 36 and a capacitor 37 which is a capacitor element grounded to ground, so that the printed wiring board 3 housed in the metal box body 2 can be provided. It does not take extra space of). In addition, impedance matching between the VHF end-to-end tuning circuit 22 and the VHF mixer 12 and impedance matching between the UHF end-to-end tuning circuit 25 and the UHF mixer 15 can be easily obtained.

Further, when the first low pass filter 18 and the second low pass filter 19 are induction M type low pass filters as shown in Fig. 1, the VCO exists in the range up to the vicinity of the cutoff frequency. Since harmonics from (10) can be attenuated, many disturbing signals generated in the VHF mixer 12 or the UHF mixer 15 are suppressed.

The second capacitor 28 of the first low pass filter 18 shown in FIG. 1, the fourth capacitor 31 of the second low pass filter 19, or the capacitor 37 shown in FIG. Since the capacitors are grounded to ground, the floating capacitors 40 formed between the two conductor patterns 38 and 39 formed on the printed wiring board 3 as shown in FIG. ) Can be substituted. Then, for example, the coil 36 of the low pass filter 35 shown in FIG. 2 may be connected to one conductor pattern 38, and the other conductor pattern 39 may be connected to the metal box body 2. . In this way, when the stray capacitance 40 using the printed wiring board 3 is used, the capacitor 37 can be deleted.

As described above, the high frequency electronic device of the present invention includes a modulator having an oscillator, a tuner having a high frequency part, a mixer and a local oscillator, and the high frequency part has a short-term tuning circuit and a low band between the short-term tuning circuit and the mixer. Since the pass filter is connected and the cutoff frequency of the low pass filter is made higher than the highest frequency among the television signals received by the high frequency unit, harmonics of the oscillation signal from the oscillator of the modulating unit are less likely to be input to the mixer. The level of can be suppressed very low.

In addition, since the low pass filter is connected between at least the UHF end-to-end tuning circuit and the UHF mixer, the high frequency electronic device of the present invention can effectively prevent the generation of disturbance signals.

In addition, since the low-pass filter of the present invention is composed of an L-type low pass filter composed of an inductance element and a capacitor element, the high-frequency electronic device can be simply composed of two components, thereby providing a space for a printed wiring board. There is no extra charge. In addition, the impedance matching between the stage tuning circuit and the mixer can be easily obtained.

In addition, the high-frequency electronic device of the present invention is composed of a low-pass filter of the induction M-type, so that it is possible to attenuate harmonics from the oscillator of the modulator in the range up to the cutoff frequency. Many disturbing signals generated are suppressed.

In addition, since the high frequency electronic device of the present invention is formed of a capacitance element of a low pass filter grounded with a stray capacitance formed between two conductor patterns provided on a printed wiring board, no capacitor is used and the parts are reduced. can do.

Claims (10)

A metal box body, a printed wiring board housed in the metal box body, a modulator configured on the printed wiring board and having an oscillator, a high frequency section configured to selectively receive and output a television signal on the printed wiring board; And a tuner section having a mixer for frequency converting the selected television signal output from the high frequency section, and a local oscillator for supplying a local oscillation signal to the mixer, wherein the high frequency section inputs the selected television signal to the mixer. A high pass filter having a tuning circuit and connecting a low pass filter between the inter-step tuning circuit and the mixer, wherein the cutoff frequency of the low pass filter is higher than the highest frequency among the television signals received by the high frequency section. Electronics. The method of claim 1, The high frequency unit has a UHF high frequency unit for selectively receiving and outputting the UHF band television signal, the mixer has a UHF mixer for frequency converting the selected UHF band television signal output from the UHF high frequency unit, the local oscillator is the UHF A UHF local oscillator for supplying a local oscillation signal to a mixer, and having a UHF stage-to-end tuning circuit for inputting the selected UHF band television signal to the UHF mixer in the UHF high-frequency section, and providing the low pass filter to at least the UHF stage. A high frequency electronic device connected between a tuning circuit and said UHF mixer. The method of claim 2, And the low pass filter comprises an L type low pass filter comprising a capacitor connected between an inductance element and one end of the inductance element and a ground. The method of claim 3, wherein And the capacitance element is formed of a stray capacitance formed between two conductor patterns provided on the printed wiring board. The method of claim 2, The low pass filter is an inductive M type low pass filter comprising an inductance element and a capacitor connected in parallel with each other, and an inductance element connected in parallel with each other and a capacitor connected between one end of the capacitor and ground. High frequency electronics, characterized in that configured. The method of claim 5, And the capacitance element is formed of a stray capacitance formed between two conductor patterns provided on the printed wiring board. The method of claim 1, And the low pass filter comprises an L type low pass filter comprising an inductance element and a capacitor connected between one end of the inductance element and ground. The method of claim 7, wherein And the capacitance element is formed of a stray capacitance formed between two conductor patterns provided on the printed wiring board. The method of claim 1, The low pass filter is an inductive M type low pass filter comprising an inductance element and a capacitor connected in parallel with each other, and an inductance element connected in parallel with each other, and a capacitor connected between one end of the capacitor and ground. High frequency electronics, characterized in that configured. The method of claim 9, And the capacitance element is formed of a stray capacitance formed between two conductor patterns provided on the printed wiring board.