JPH07274083A - Double super tuner - Google Patents

Abstract

PURPOSE:To prevent disturbance due to the leakage of a local oscillating signal to an input terminal as against another television receiver, etc., in a double super tuner. CONSTITUTION:The double super tuner is constituted in such a way that an input terminal 12 is fitted on one of the longitudinal side surface of a metallic case 22, a second local oscillator 18 is arranged in the neighborhood of the other longitudinal side surface and an output circuit 20 is arranged between the second local oscillator 18 and a first intermediate frequency filter 17. Therefore, in the section room of the second local oscillator 18, the first intermediate frequency filter 17 is provided across the section room of the output circuit 20 so that the leakage of the osccilation frequency signal of the second oscillator 18 to the intermediate frequency filter 17 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double super tuner used for a television receiver, a CATV receiver, a satellite broadcast receiver and the like.

[0002]

2. Description of the Related Art A conventional double super tuner will be described below.

FIG. 4 is a perspective view showing the arrangement of each circuit of a conventional double super tuner. In FIG. 4, the input terminal 1, the input section low-pass filter 2 connected to this input terminal 1, the input section band-pass filter 3 connected to this input section low-pass filter 2, and the output of this input section band-pass filter 3 are The first input is connected to one input and the output of the first local oscillator 4 is connected to the other input.
Mixing circuit 5, a first intermediate frequency filter 6 to which the output of the first mixing circuit 5 is connected, and an output of the first intermediate frequency filter 6 is connected to one input and the other input Is connected to the output of the second local oscillator 7.
The mixing circuit 8, the output circuit 9 to which the output of the second mixing circuit 8 is connected, and the output terminal 10 to which the output of the output circuit 9 is connected The input terminal 1 is mounted on one vertical side surface of the housing 11, the output circuit 9 is disposed adjacent to the other vertical side surface, and the second local portion is adjacent to the output circuit 9. Oscillator 7
And the second mixing circuit 8 is arranged, and this compartment is also adjacent to the compartment of the first intermediate frequency filter 6.

[0004]

However, in the above configuration, the compartment containing the second local oscillator 8 is always adjacent to the first intermediate frequency filter 6, and the second local oscillator 8 and the intermediate frequency filter are provided. Since the filter 6 is connected on the printed wiring board at a part on the back side of the compartment, this part does not block the oscillation frequency signal of the second local oscillator 8, and the second local oscillator 8 and the above-mentioned Since the distance to the first intermediate frequency filter 6 becomes close, the second local oscillator 8
Of the oscillating frequency signal to the intermediate frequency filter 6 is likely to occur, and as a result, the local oscillating signal to the input terminal 1 is leaked, and the other television receiver or CAT.
There is a problem that it interferes with reception of the V receiver.

The present invention solves such a problem, and an object thereof is to prevent the output of the second local oscillator from leaking to the first intermediate frequency filter.

[0006]

In order to achieve this object, a double super tuner according to the present invention has an input terminal mounted on one vertical side surface of a metallic housing and the second super tuner located near the other vertical side surface. A local oscillator is arranged, and the output circuit is arranged between the second local oscillator and the first intermediate frequency filter.

[0007]

With this configuration, the compartment of the second local oscillator is not directly adjacent to the first intermediate frequency filter but sandwiches the compartment of the output circuit, so that the compartment of the second local oscillator is first At least two partition wall surfaces are provided between the intermediate frequency filters, and the second local oscillator and the first intermediate frequency filter are arranged apart from each other by the partition of the output circuit. It becomes difficult for the oscillation frequency signal of the second oscillator to leak to the intermediate frequency filter. Further, the second local oscillator is arranged farthest from the input terminal, and even if the second oscillation frequency signal leaks to the intermediate frequency filter, the leakage to the input terminal should be prevented. You can

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an arrangement of each circuit of a double super tuner according to an embodiment of the present invention, and FIG. 2 is a block diagram thereof.

1 and 2, the input terminal 12 and
The input section low-pass filter 13 connected to the input terminal 12, the output of the input section low-pass filter 13, and the band switch type filter 14 divided into three bands, and the output of the band switch type filter 14 are Is connected to one input and the other input has a first
First mixing circuit 1 to which the output of the local oscillator 15 is connected
6 is connected to the output of the first mixing circuit 16
The intermediate frequency filter 17 and the first intermediate frequency filter 1
The output of 7 is connected to one input and the other input is connected to the second mixing circuit 19 to which the output of the second local oscillator 18 is connected, and the output of this second mixing circuit 19. The output circuit 20, the output terminal 21 to which the output of the output circuit 20 is connected, and the prescaler circuit 23 to which the output of the first local oscillator 15 is connected. It is installed in the drawing room.

Further, these circuits correspond to the second local oscillator 1
8 and the second mixing circuit 19 are formed on the printed wiring board 24. The second local oscillator 18 is formed on one side of an alumina substrate 25 and is erected on the printed wiring board 24. Further, the second mixing circuit 19 is formed on the alumina substrate 26, and is erected on the printed wiring board 24 like the second local oscillator 18. A single balanced mixer with a half-wavelength microstrip line is formed on one side of the alumina substrate 26, and the conductor on the opposite side of the microstrip line is grounded.

Further, the input low-pass filter 13
Are provided to attenuate unwanted frequencies above the input frequency. The band-switch filter 14 is composed of three filters, a low-pass filter 14a, a band-pass filter 14b, and a high-pass filter 14c. This low pass filter 14a
Is the frequency division frequency of the prescaler circuit 23 in the pass band, and the band pass filter 14b and the high pass filter 14
c is provided so that the divided frequency of the prescaler circuit 23 is in the attenuation range. These filters 14a,
The pass bands of 14b and 14c are divided as shown in FIG. 3, the low pass filter 14a has a pass band at a frequency of 168 MHz or lower, and the band pass filter 14b has a pass band of 168.
The frequency range from MHz to 378MHz is the passband,
The high pass filter 14c has a pass band at a frequency of 378 MHz or higher. At this time, when the oscillation frequency of the first local oscillator 15 is 2.2 GHz from 1.4 GHz and the division ratio of the prescaler circuit 23 is 256 divisions, the division frequency naturally enters the pass band of the low pass filter 14a. ing.

The arrangement of the compartments will be described below in detail with reference to FIG. First, the input terminal 12 is mounted on one vertical side surface of the metallic housing 22. A compartment of the input filter 13 is provided adjacent to the vertical side surface of the input terminal 12. The compartment of the input filter 13 is adjacent to the compartment of the band switch type filter 14 and the prescaler circuit 23, and the compartment of the band switch type filter 14 is adjacent to the compartment of the first mixing circuit 16 and the prescaler circuit 23. However, the compartment of the first local oscillator 15 is adjacent to the compartment of the prescaler circuit 23. The first local oscillator 15 is also adjacent to the first mixing circuit 16. Next, between the first mixing circuit 16 and the first intermediate frequency filter 17, there is provided a compartment 27 having a space in which no circuit is configured. Next, the compartment of the first intermediate frequency filter 17 has the second mixing circuit 1
9 and the compartment of the output circuit 20. A second local oscillator 18 is arranged adjacent to the output circuit 20 and the second mixing circuit 19, and the output circuit 2
The output terminal 21 is attached to 0. That is, in this state, the second local oscillator 18 is provided in parallel with the compartment having a part of the vertical side surface opposite to the one side surface on which the input terminal 12 is mounted as one wall surface. .

Next, the band switch type filter 14
In this compartment, the circuit of the high-pass filter 14c is arranged adjacent to the compartment of the prescaler circuit 23, and the prescaler circuit 2 of the high-pass filter 14c is arranged.
The band pass filter 14b is arranged so as to be adjacent to the side opposite to the compartment of No. 3, and the band pass filter 14b
The low-pass filter 14a is arranged so as to be adjacent to. A grounded copper foil is provided between the filters. Further, the inductors that form these filters are made of copper foil on the printed wiring board 24.

As described above, according to the present embodiment, the compartment of the second local oscillator 18 is not directly adjacent to the compartment of the first intermediate frequency filter 17, but the compartment of the output circuit 20 is Since it is sandwiched between the second local oscillator 18 and the first intermediate frequency filter 17, at least two or more compartment wall surfaces are provided, and the second local oscillator 18 and the first intermediate frequency filter 17 output The circuit 20 is arranged at a position distant from the compartment. Therefore, the second
Intermediate frequency filter 17 of the oscillation frequency signal of the oscillator 18
Is less likely to leak. Further, the second local oscillator 18 is disposed farthest from the input terminal 12, and the intermediate frequency filter 1 for the second oscillation frequency signal is provisionally provided.
Even if a leak to the input terminal 7 occurs, the leak to the input terminal 12 can be prevented.

Further, in this embodiment, the second mixing circuit 19
Similarly to the output circuit 20, the compartment of the second local oscillator 18
And the intermediate frequency filter 17 are arranged between the intermediate frequency filter 17 and the intermediate frequency filter 17, and one surface of the alumina substrate 26 constituting the second mixing circuit 19 is grounded. Therefore, the compartment of the second local oscillator 18 also sandwiches the compartment of the second mixing circuit 19 between it and the compartment of the first intermediate frequency filter 17.
Since the second local oscillator 18 has at least two or more compartment wall surfaces between the first intermediate frequency filter 17, leakage of the oscillation frequency signal of the second oscillator 18 to the intermediate frequency filter 17 occurs. It gets harder. Moreover, since one side of the alumina substrate 26 is grounded, this compartment has another compartment wall surface.
Even if the distance between the intermediate frequency filters 17 of the oscillation frequency signal of the second oscillator 18 is shortened, the leakage of the oscillation frequency signal of the second oscillator 18 to the intermediate frequency filter 17 is less likely to occur. Therefore, the compartment of the second mixing circuit 19 can be downsized. Also, this second mixing circuit 1
Since 9 is erected on the printed wiring board 24 as a module substrate, a substrate made of a material different from that of the printed wiring board 24 can be used. Here, by using an alumina substrate having a high dielectric constant and an excellent water absorption rate (having a water absorption rate of 0), downsizing and high moisture resistance can be obtained.

Further, in the present embodiment, a band switch type filter 14 and a prescaler circuit 23 are provided between the compartment of the first local oscillator 15 and the compartment of the input low-pass filter 13. Therefore, at least two or more partition wall surfaces are provided between the partition of the first local oscillator 15 and the partition of the input low-pass filter 13, and the input of the oscillation frequency signal of the first local oscillator 15 is provided. The low-pass filter 13 is less likely to leak into the compartment. Even if the oscillation frequency signal of the first local oscillator 15 leaks to the adjacent band switch filter 14 and enters the input low-pass filter 13 between the prescaler circuit 23 and the band switch filter 14, the leaked signal The oscillating frequency signal of the local oscillator 15 of No. 1 is attenuated by the input low-pass filter 13 that attenuates frequencies above this input frequency, and does not leak from the input terminal 12 to the outside of the device. This is the second local oscillator 18
There is of course the same effect for the leakage of the oscillating frequency signal to the input terminal 12 side. Therefore, by arranging the compartments of each circuit as in this embodiment, it is possible to prevent the leakage of the oscillation frequency signal of each local oscillator, and as a result, it is possible to shorten the distance from each local oscillator to the input terminal. Therefore, it is possible to realize a double super tuner that is small in size and has no leakage of the oscillation frequency signal of the local oscillator.

Further, in the double super tuner of this embodiment, the band pass filter 14b is provided between the compartment of the prescaler circuit 23 and the low pass filter 14a.
A high pass filter 14c is arranged. Since the frequency division frequency of the prescaler circuit 23 is in the attenuation region of the band pass filter 14b and the high pass filter 14c, the signal of the frequency division frequency is attenuated. Further, with this arrangement, the interval between the low-pass filter 14a and the prescaler circuit 23 can be increased, and the low-pass filter circuit 14 at the frequency division frequency of the prescaler circuit 23 can be obtained.
It is possible to prevent the entry into a. Further, since the grounded copper foil is arranged between the respective filters, it is possible to further prevent the frequency dividing frequency of the prescaler circuit 23 from entering the respective filters, and the respective filters can be grounded at the shortest distance. It will be possible.

Although the prescaler circuit is used in this embodiment, it goes without saying that the same effect can be obtained even in the case of a PLL circuit.

[0020]

As described above, according to the present invention, the input terminal is mounted on one vertical side surface of the metallic casing, and the second local oscillator is arranged near the other vertical side surface. Two
Since the output circuit is arranged between the local oscillator and the first intermediate frequency filter, the compartment of the second local oscillator is not directly adjacent to the first intermediate frequency filter. Instead, the compartment of the output circuit is sandwiched. As a result, at least two or more compartment wall surfaces are provided between the second local oscillator and the first intermediate frequency filter, and the second local oscillator and the first intermediate frequency filter are separated from each other in the compartment of the output circuit. Will be placed away from the second
The oscillation frequency signal of the oscillator is less likely to leak to the first intermediate frequency filter. Further, the second local oscillator is arranged farthest from the input terminal, and even if the second oscillation frequency signal leaks to the first intermediate frequency filter, it does not leak to the input terminal. Can be prevented.

As a result, the leakage of the local oscillation signal to the input terminal does not occur, and other television receivers or CATV
It does not interfere with the reception of the receiver.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an arrangement of respective circuits of a double super tuner according to an embodiment of the present invention.

[Figure 2] Block diagram of the same double super tuner

3 (a), (b) and (c) are frequency characteristic diagrams of band switch filters of the same double super tuner.

FIG. 4 is an exploded perspective view showing an arrangement of each circuit of a conventional double super tuner.

[Explanation of symbols]

 12 Input Terminal 14 Band Switch Filter 15 First Local Oscillator 16 First Mixing Circuit 17 First Intermediate Frequency Filter 18 Second Local Oscillator 19 Second Mixing Circuit 20 Output Circuit 21 Output Terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Motoki Sugiyama, 1006 Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. An input terminal, an input filter connected to this input terminal, an output of this input filter is connected to one input, and the other input receives the output of the first local oscillator. A connected first mixing circuit, a first intermediate frequency filter to which an output of the first mixing circuit is connected, an output of the first intermediate frequency filter is connected to one input, and the other A second mixing circuit to which the output of the second local oscillator is connected, an output circuit to which the output of the second mixing circuit is connected, and an output terminal to which the output of the output circuit is connected. In the same metal housing,
An input terminal is mounted on one vertical side surface of the housing, the second local oscillator is arranged near the other vertical side surface, and between the second local oscillator and the first intermediate frequency filter. A double super tuner equipped with the output circuit. 2. A small printed wiring board, a mixer formed on one side of the printed wiring board, and a back side of the mixer in a compartment provided with a second mixing circuit in the housing. 2. The double super tuner according to claim 1, further comprising a conductor provided so as to be grounded, and the printed wiring board is arranged parallel to one side surface of the compartment of the second mixed circuit. 3. An input terminal, an input low-pass filter connected to this input terminal, a band switch type filter connected to the output of this input low pass filter, and the output of this band switch type filter being one input. A first mixing circuit connected to the output of the first local oscillator and a first intermediate frequency filter connected to the output of the first mixing circuit, The output of the first intermediate frequency filter is connected to one input, and the other input is connected to the second mixing circuit to which the output of the second local oscillator is connected and the output of this second mixing circuit. The output circuit and the output terminal to which the output of the output circuit is connected are provided in the same metal housing, and the input terminal is mounted on one vertical side surface of the housing and adjacent to the vertical side surface. In the compartment provided A double super tuner in which the input low-pass filter is provided, and the compartment of the band switch filter is arranged between the compartment of the input low-pass filter and the compartment of the first local oscillator. 4. A prescaler circuit compartment for dividing the oscillation frequency of the first oscillator is provided adjacent to the compartment provided with the first oscillator in the housing, and the prescaler circuit compartment is provided in the compartment. A compartment of the band switch type filter is provided adjacent to the compartment of the band switch type filter, and one of the compartments of the prescaler circuit is adjacent to the compartment of the prescaler circuit, and the division frequency of the prescaler circuit is its attenuation range. A high-pass filter, a band-pass filter adjacent to the other of the high-pass filters where the divided frequency is in the attenuation band, and a low-pass filter where the divided frequency of the prescaler circuit is in the pass band are adjacent to the band-pass filter. The double super tuner according to claim 3, wherein the double super tuners are arranged in parallel. 5. A band switch type filter is formed by an inductance formed by a conductor provided on a printed wiring board and a capacitor mounted on the printed wiring board, and the frequency divider of the prescaler circuit. 5. The double super tuner according to claim 4, wherein a grounded conductor is arranged between a low pass filter whose frequency is its pass band and a band pass filter and a high pass filter whose frequency division frequency is its attenuation band.