JP2000224067A - Composite pll tuner unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of a composite PLL tuner, and at the same time, to constitute such a tuner unit that the influence at the time of inputting BUS data can be reduced. SOLUTION: A composite PLL tuner unit is composed of a modulator section 3, which mixes one-side high-frequency signals distributed from a signal distributing circuit 2 connected to an antenna input terminal 1 with video signals and audio signals inputted from the outside and outputs the mixed signals through a television output terminal 6, a tuner section 4 which fetches the signal of a receiving channel from the other-side high-frequency signals distributed from the distributing circuit 2, amplifies, and converts the amplified signals into intermediate-frequency signals, and one PLL circuit 8 which controls the oscillation frequencies of a local oscillation circuit 37 of each modulator section 3 and the local oscillation circuits 44 and 54 respectively of the blocks for UHF and VHF bands of the tuner section 4. The circuit sections are arranged on the same substrate, and at the same time, the antenna input terminal 1 and the television output terminal 6 are arranged in the same end section of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite type P used for a video tape recorder (hereinafter abbreviated as VTR) or the like.
The present invention relates to an LL tuner unit, and more particularly, to a composite type PLL tuner unit that realizes downsizing and cost reduction of a tuner unit.

[0002]

2. Description of the Related Art A conventional composite PLL used for a VTR or the like.
The tuner unit modulates a video signal and an audio signal output from a VTR or the like from a tuner unit for extracting a signal of a desired frequency from the antenna signal, and transmits the modulated signal to a TV receiver or the like connected at a subsequent stage in the same manner as the antenna signal. And a modulator section for outputting.

FIG. 4 is a block diagram showing a schematic configuration of such a conventional composite PLL tuner unit.

That is, the composite PLL tuner unit is roughly divided into an antenna input terminal 1, a signal distribution circuit 2, a modulator unit 3, a tuner unit 4, and a television output terminal 6.

The modulator section 3 includes a first high-frequency amplifier circuit 31, a mixing circuit 32, a buffer amplifier 33, a mixer circuit 34, a video modulation circuit 35, an audio modulation circuit 36, a first local oscillation circuit 37, a modulator PLL circuit 38, It is constituted by a crystal oscillator 39.

The tuner unit 4 comprises a UHF band block and a VHF band block. The UHF band block includes a first variable band-pass filter circuit 41, a second high-frequency amplifier circuit 42, and a second variable band-pass filter circuit. 43, a second local oscillator circuit 44, a mixer circuit 45, a commonly used tuner PLL circuit 46, a crystal oscillator 47, and an intermediate frequency amplifier circuit 48,
The band block includes a high-pass filter circuit 56, a first
A variable band-pass filter circuit 51, a second high-frequency amplifier circuit 52, a second variable band-pass filter circuit 53, a third local oscillation circuit 54, a mixer circuit 55, a commonly used tuner PLL circuit 46, a crystal oscillator 47, An intermediate frequency amplifying circuit 48 is provided.

In the above configuration, the signal input from the antenna input terminal 1 is divided into two by the signal distribution circuit 2, and one signal is input to the tuner unit 4 and the other signal is input to the modulator unit 3.

The signal input to the modulator section 3 is amplified by the first high-frequency amplifier circuit 31 by an amount corresponding to the decrease in gain by passing through the signal distribution circuit 2, and
2 is input.

On the other hand, a video signal externally input to the modulator section 3 is subjected to amplitude modulation (AM) by a video modulation circuit 35.
Modulated) and oscillated by the first local oscillation circuit 37.
Mixing with the video carrier of the local oscillation signal
Is input to The audio signal input from the outside to the modulator section 3 is frequency-modulated (FM modulated) by the audio modulation circuit 36 and mixed with the audio subcarrier of the first local oscillation signal oscillated by the first local oscillation circuit 37. The signal is input to the mixer circuit 34. At this time, the center frequency of the video carrier is determined by the first local oscillation signal, and the control is performed by the modulator PLL circuit 38. The center frequency of this video carrier is the frequency of the channel. Also,
A modulator PLL circuit control signal (modulator BUS data) S1 is input to the modulator PLL circuit 38 from the outside.

[0010] The modulated video signal and audio signal are mixed in a mixer circuit 34 and input to a mixing circuit 32 via a buffer amplifier 33.

In the mixing circuit 32, the first high-frequency amplification circuit 3
The antenna input signal input from the input unit 1 and the composite video signal input from the modulator unit 3 are mixed and output to the television output terminal 6.

On the other hand, the signal input to the tuner unit 4 is
The signal is distributed to a UHF band block and a VHF band block. In the UHF band block, a signal required by a first variable bandpass filter circuit 41 including a variable capacitance diode or the like capable of changing a center frequency of a pass frequency band and the like. Is taken out. In the VHF band block, a VHF band signal is first extracted by the high-pass filter circuit 56, and the first variable band-pass filter circuit 51 including a variable capacitance diode or the like capable of changing the center frequency of the pass frequency band. The required signal is extracted. At this time, the UHF band block and the VHF band block do not operate at the same time, and only one of them operates with a band switching switch (not shown).

Each of the first variable bandpass filter circuits 41,
The signals output from 51 are input to the second high-frequency amplifier circuits 42 and 52, respectively, and further input to the second variable band-pass filter circuits 42 and 52, respectively, to extract necessary signals again.

After that, the signal extracted by the second variable band-pass filter circuit 42 and the second local oscillation signal oscillated by the second local oscillation circuit 44 or the second variable band-pass filter circuit 52 extracts the signal. The mixed signal and the third local oscillation signal oscillated by the third local oscillation circuit 54 are mixed by a mixer circuit 45, converted into an intermediate frequency signal by a superheterodyne method, amplified by an intermediate frequency amplifier circuit 48, and Is output to At this time, the frequency of the reference signal of the second local oscillation signal oscillated by the second local oscillation circuit 45 and the frequency of the third local oscillation signal oscillated by the third local oscillation circuit 54 is the P
This tuner P is controlled by the LL circuit 46.
To the LL circuit 46, a tuner PLL circuit control signal (tuner BUS data) S2 is input from outside.
FIG. 5 shows signal paths in the modulator unit 3 and the tuner unit 4 described above. However, the block diagram shown in FIG. 5 is a schematic diagram, and does not necessarily correspond to the block shown in FIG.

[0015]

However, recent TVs
2. Description of the Related Art Receivers, VTRs, and the like, which are equipped with a variety of functions, are becoming widespread.
It is managed by a microcomputer provided inside the TR or the like, and each function is controlled by BUS data. As described above, the composite PLL tuner unit is also one of the units controlled by the BUS data S1 and S2.

In this BUS data, since the independent BUS data S1 and S2 are input to the modulator unit 3 and the tuner unit 4, respectively, the microcomputer that manages the BUS data is also connected to the respective BUS data.
Two pieces are required in accordance with the US data S1 and S2.

The fact that there are two types of input BUS data means that, for example, a BU required for the modulator unit 3 is required.
When the S data S1 is input, there is a problem that the signal of the BUS data S1 affects the tuner unit 4, and unnecessary signals are mixed or output. This is the same when the necessary BUS data S2 is input to the tuner unit 4. The signal of the BUS data S2 affects the modulator unit 3, and unnecessary signals are mixed or output.

In addition, as the functions added to the VTR and the like increase, the size of the device itself is required to be reduced, so that the ratio of the space that can be occupied by the composite tuner unit is limited. In addition, there is a demand for energy saving, and further, a cost reduction of the composite tuner unit is also demanded.

The present invention has been made in order to solve such a problem. It is an object of the present invention to combine a PLL circuit for an internal modulator and a PLL circuit for a tuner into one circuit to reduce the size and reduce the power consumption. While reducing costs, BUS
It is an object of the present invention to provide a composite PLL tuner unit having a unit structure that reduces the influence of data input.

[0020]

In order to solve the above-mentioned problems, a composite PLL tuner unit according to the present invention comprises a signal distribution circuit connected to an antenna input terminal, and one high-frequency signal distributed from the signal distribution circuit. Is amplified by the first high-frequency amplifier circuit, and the video signal and the audio signal input from the outside are respectively modulated to be converted into the video carrier and the audio sub-carrier of the first local oscillation signal oscillated by the first local oscillation circuit. Mixing, mixing the mixed signal with the output signal of the first high-frequency amplifier circuit, and outputting the mixed signal from a television output terminal; and transmitting the other high-frequency signal distributed by the signal distribution circuit to a UHF band block and VHF. And distributed input to the block for the band, and each block includes a first variable band-pass filter circuit, a second high-frequency amplifier circuit, and a second variable band-pass circuit. Filter circuit, a local oscillation circuit,
A tuner section comprising a mixer circuit for mixing an output of the second variable band-pass filter circuit and a local oscillation signal oscillated by the local oscillation circuit; an oscillation frequency of the first local oscillation circuit; a local oscillation of the UHF band block; A single PLL circuit for controlling the oscillation frequency of the circuit and the oscillation frequency of the local oscillation circuit of the VHF band block, and these signal distribution circuit, modulator section, tuner section and PLL circuit are arranged on the same substrate. In addition, the antenna input terminal and the television output terminal are arranged at the same end on the substrate. That is, the BUS for PLL control input to the modulator section and the tuner section.
By using one data line, a structure that does not affect each other can be obtained.

Further, in the composite PLL tuner unit of the present invention, in the above configuration, the modulator section is disposed on the input / output terminal side on the substrate, and the tuner section is disposed on the side opposite to the input / output terminal side. The PLL circuit is arranged at a boundary between the modulator section and the tuner section, and the first local oscillation circuit, the local oscillation circuit of the UHF band block, and the VHF band block are sandwiched by the PLL circuit. And a local oscillation circuit. That is, by arranging the first local oscillation circuit, the local oscillation circuit of the UHF band block, and the local oscillation circuit of the VHF band block adjacent to each other with the PLL circuit interposed therebetween, the BUS data from the PLL circuit to the first local oscillation circuit can be obtained. And the BUS data input line to each local oscillation circuit of the UHF band block and the VHF band block can be shortened, so that the influence on each circuit block can be further reduced.

In the composite PLL tuner unit according to the present invention, the signal distribution circuit, the modulator section, the tuner section, and the PLL circuit are each electromagnetically cut off by an electromagnetic shield plate. And the circuits constituting the tuner section are each electromagnetically shielded by an electromagnetic shield plate, and these electromagnetic shield plates are electrically connected to the outer side surface of a chassis for fixing the substrate. It is. That is, the influence of each circuit block can be further reduced by electromagnetically shielding each circuit block by the electromagnetic shield plate.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a composite type PLL tuner unit according to the present invention.

In the figure, 1 is an antenna input terminal, 2
Is a signal distribution circuit, 3 is a modulator section, 4 is a tuner section, 6 is a television output terminal, and the modulator section 3
A first high-frequency amplifier circuit 31, a mixing circuit 32, a buffer amplifier 33, a mixer circuit 34, a video modulation circuit 35, an audio modulation circuit 36, and a first local oscillation circuit 37;
The UHF band block of the tuner unit 4 includes a first variable bandpass filter circuit 41, a second high-frequency amplifier circuit 42,
The VHF band block includes a second variable band-pass filter circuit 43, a second local oscillation circuit 44, and a mixer circuit 45. The VHF band block includes a high-pass filter circuit 56, a first variable band-pass filter circuit 51, and a second high-frequency amplifier circuit 5.
The configuration of the second complex band-pass filter circuit 53, the third local oscillation circuit 54, and the mixer circuit 55 is exactly the same as the configuration of the conventional composite PLL tuner unit shown in FIG.

According to the present invention, in the above configuration, the modulator PLL circuit 38 and the tuner PLL circuit 46 provided separately in the conventional composite type PLL tuner unit are commonly used by one PLL circuit 8. In this configuration, external BUS data input is integrated into one input line 81. Thus, the PLL
By using one circuit 8, the space for arranging the PLL circuit on the substrate A, which will be described later, is reduced to half that of the conventional circuit.
Since only one crystal oscillator 9 is required for the LL circuit 8, a significant space saving and a reduction in cost due to a reduction in the number of components can be achieved. Further, the reduction of microcomputers and PLL circuits for managing BUS data leads to energy saving. In addition, FIG.
The signal path of such a composite type PLL tuner unit of the present invention is shown. However, the block diagram shown in FIG. 2 is a schematic diagram, and is not necessarily 1: 1 with the block shown in FIG.
Is not supported.

FIG. 3A shows a composite PL according to the present invention.
FIG. 3B is a schematic plan view showing a state in which the L tuner unit is mounted on a board, and FIG.

That is, the antenna input terminal 1 and the television output terminal 6 are provided at the left end of the board A, and the modulator section 3 is arranged on the side of the terminals 1 and 6 on the board A. Has a tuner section 4 on the opposite side. The ratio of the arrangement area is such that the modulator section 3 and the tuner section 4 are divided approximately 3: 7 from the terminals 1 and 6 side.
A PLL circuit (indicated by a dashed line in FIG. 3A) 8 is arranged at a boundary between the modulator section 3 and the tuner section 4 and a first local oscillation circuit is provided on the upper left side of the PLL circuit 8. The second local oscillation circuit 44 of the UHF band block and the third local oscillation circuit 54 of the VHF band block are arranged on the lower right side.

Further, the signal distribution circuit 2 is disposed at the upper left of the substrate A, and the first high frequency amplifier circuit 31 is disposed between the antenna input terminal 1 and the television output terminal 6 at the left end of the substrate A. The mixing circuit 32 is disposed below the mixing circuit 32. on the other hand,
On the substrate A, the first variable band-pass filter circuits 41 and 51 are arranged adjacent to the upper side of the second local oscillation circuit 44, and the first variable band-pass filter circuits 41 and 51 are arranged.
The second variable bandpass filter circuits 43 and 53 are arranged adjacent to the third local oscillation circuit 54 and the third local oscillation circuit 54.

That is, in the composite PLL tuner unit of the present invention, the first local oscillation circuit 37, the second local oscillation circuit 44, and the third local oscillation circuit 54 sandwich the PLL circuit 8 therebetween.
Are arranged opposite to each other to reduce the influence between the oscillation circuits that oscillate at different frequencies.
Further, by arranging the first local oscillation circuit 37, the second local oscillation circuit 44, and the third local oscillation circuit 54 adjacent to each other with the PLL circuit 8 interposed therebetween, a BUS from the PLL circuit 8 to the first local oscillation circuit 37 is provided. Data input line 81a
(See FIG. 1), and BU to each local oscillation circuit 44, 54
Since the S data input line 81b (see FIG. 1) can be shortened, it is possible to further reduce the influence on other circuit blocks. Further, in order to prevent the oscillation signal of the first local oscillation circuit 37 from leaking outside from the antenna input terminal 1 and the television output terminal 6, the first local oscillation circuit 37 is located at the same distance from the antenna input terminal 1 and the television output terminal 6. Place in position.

The local oscillation circuits 37, 4
The effects of 4,54 also affect other circuits. Therefore, in the composite type PLL tuner unit of the present invention, the signal distribution circuit 2 and the modulator unit 3 are used in order to make the local oscillation circuits 37, 44 and 54 less and less likely to affect other circuits. The tuner unit 4 and the tuner unit 4 are each electromagnetically shielded by an electromagnetic shield plate, and the circuits constituting the modulator unit 3 and the circuits constituting the tuner unit 4 are also electromagnetically shielded by the electromagnetic shield plate. Circuit blocks that need to be separated and arranged by the electromagnetic shield plate are mainly circuit blocks related to high frequency.

That is, the boundary portion between the modulator section 3 and the tuner section 4 is electromagnetically shielded by an electromagnetic shield plate 21a electrically connected to the external side chassis 11 for fixing the substrate A, and a shield cover (not shown). Electrical connection is made to reduce the influence between the oscillation circuits. Further, the second local oscillation circuit 44 and the third local oscillation circuit 54 and the first variable band-pass filter circuits 41 and 51 and the second variable band-pass filter circuits 43 and 53 have the same potential as that of the external chassis 11. Electromagnetic shield plate 21b
The second local oscillation circuit 44 and the third local oscillation circuit 54 are also separated by the electromagnetic shield plate 21c, and the first variable band-pass filter circuits 41 and 51 and the second local oscillation circuit
The variable band pass filter circuits 43 and 53 are also separated by the electromagnetic shield plate 21d.

The signal distribution circuit 2, the first high-frequency amplification circuit 31, and the first local oscillation circuit 37 are also separated by the electromagnetic shield plate 21e, and the mixing circuit 32 and the first high-frequency amplification circuit 31, The first local oscillation circuit 37 is also separated by the electromagnetic shield plate 21f, and the first high-frequency amplifier circuit 31 and the first local oscillation circuit 37 are further separated by the electromagnetic shield plate 21g. These electromagnetic shield plates 21 b to 21 g are also electrically connected to the external side chassis 11 for fixing the board A.

[0034]

The composite PLL tuner unit according to the present invention comprises a signal distribution circuit connected to an antenna input terminal, a modulator section, a tuner section, and a first section of the modulator section.
The oscillation frequency of the local oscillation circuit, and the oscillation frequency and VHF of the local oscillation circuit of the UHF band block of the tuner section.
One PLL circuit for controlling the oscillation frequency of the local oscillation circuit of the band block is provided. That is, the modulator PLL circuit and the tuner P
By configuring the LL circuit and the PLL circuit to be commonly used by one PLL circuit and integrating the external BUS data input into one input line, the influence on the peripheral circuits can be reduced. The arrangement space of the PLL circuit on the substrate can be reduced by half. Also, P
Since only one crystal oscillator is required for the LL circuit, significant space saving and cost reduction by reducing the number of components can be achieved. Further, by reducing the number of microcomputers and PLL circuits for managing BUS data, it is possible to save energy by reducing power.

Further, the composite type PLL tuner unit of the present invention has a modulator section disposed on the input / output terminal side on the substrate, a tuner section disposed on the side opposite to the input / output terminal side, and a modulator section and a tuner section. At the boundary with
An LL circuit is arranged, and a first local oscillation circuit, a local oscillation circuit of a UHF band block, and a local oscillation circuit of a VHF band block are arranged with the PLL circuit interposed therebetween. That is, by arranging the first local oscillation circuit, the local oscillation circuit of the UHF band block, and the local oscillation circuit of the VHF band block adjacent to each other with the PLL circuit interposed therebetween, the BUS data from the PLL circuit to the first local oscillation circuit can be obtained. And the input line of BUS data to each local oscillation circuit of the UHF band block and the VHF band block can be shortened, so that the influence on each circuit block can be further reduced.

The composite PLL tuner unit of the present invention electromagnetically cuts off a signal distribution circuit, a modulator section, a tuner section, and a PLL circuit with an electromagnetic shield plate, respectively, and forms each circuit and the tuner section constituting the modulator section. Are electromagnetically shielded by an electromagnetic shield plate, and these electromagnetic shield plates are electrically connected to the outer side surface of a chassis for fixing the board. That is, the influence of each circuit block can be further reduced by electromagnetically blocking each circuit block with the electromagnetic shield plate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a composite PLL tuner unit of the present invention.

FIG. 2 is a block diagram schematically showing a signal path of the composite PLL tuner unit of the present invention.

FIG. 3A is a schematic plan view showing a state in which the composite PLL tuner unit of the present invention is mounted on a substrate, and FIG. 3B is a perspective view showing the structure of a chassis and an electromagnetic shield for fixing the substrate. .

FIG. 4 is a block diagram showing a schematic configuration of a conventional composite PLL tuner unit.

FIG. 5 is a block diagram schematically showing a signal path of a conventional composite PLL tuner unit.

[Explanation of symbols]

 Reference Signs List 1 antenna input terminal 2 signal distribution circuit 3 modulator section 4 tuner section 6 TV output terminal 8 PLL circuit 9 crystal oscillator 81, 81a, 81b input line 31 first high-frequency amplifier circuit 32 mixing circuit 33 buffer amplifier 34 mixer circuit 35 video modulation Circuit 36 Audio modulation circuit 37 First local oscillation circuit 41, 51 First variable bandpass filter circuit 42, 52 Second high-frequency amplifier circuit 43, 53 Second variable bandpass filter circuit 44 Second local oscillation circuit 45, 55 Mixer circuit 48 Intermediate frequency amplification circuit 54 Third local oscillation circuit 56 High pass filter circuit 11 External side chassis 21a to 21g Electromagnetic shield plate A Substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C025 AA03 AA05 AA08 AA09 AA25 BA18 BA25 DA05 5K020 AA02 BB09 DD13 EE01 GG01 HH13 NN05

Claims (3)

[Claims] 1. A signal distribution circuit connected to an antenna input terminal, and a first high-frequency amplifier circuit amplifies one of the high-frequency signals distributed by the signal distribution circuit, and a video signal and an audio signal input from the outside. The signals are respectively modulated and mixed with a video carrier and an audio sub-carrier of a first local oscillation signal oscillated by a first local oscillation circuit, and the mixed signal is mixed with an output signal of the first high-frequency amplification circuit to produce a television signal. A modulator section output from an output terminal, and the other high-frequency signal distributed from the signal distribution circuit,
The input is distributed to the UHF band block and the VHF band block, and each block is a first variable band-pass filter circuit, a second high-frequency amplifier circuit, a second variable band-pass filter circuit, a local oscillation circuit, and a second variable band-pass filter. A tuner section comprising a mixer circuit for mixing an output of a circuit and a local oscillation signal oscillated by a local oscillation circuit; an oscillation frequency of the first local oscillation circuit; an oscillation frequency of a local oscillation circuit of the UHF band block; VHF
A PLL circuit for controlling the oscillation frequency of the local oscillation circuit of the band block. The signal distribution circuit, the modulator section, the tuner section and the PLL circuit are arranged on the same substrate, and the antenna input terminal and A composite PLL tuner unit, wherein the television output terminals are arranged at the same end on a substrate. 2. The modulator section is disposed on an input / output terminal side of the substrate, the tuner section is disposed on a side opposite to the input / output terminal side, and the tuner section is provided at a boundary between the modulator section and the tuner section. A PLL circuit is arranged, and the first local oscillation circuit and the U
The hybrid PLL tuner unit according to claim 1, wherein a local oscillation circuit of the HF band block and a local oscillation circuit of the VHF band block are arranged. 3. The signal distribution circuit, the modulator section, the tuner section, and the PLL circuit are each electromagnetically cut off by an electromagnetic shield plate, and each circuit constituting the modulator section and each circuit constituting the tuner section are provided. 3. The hybrid PLL according to claim 1, wherein each of the electromagnetic shield plates is electromagnetically shielded by the electromagnetic shield plate, and the electromagnetic shield plates are electrically connected to an outer side surface of a chassis for fixing the substrate. Tuner unit.