JP3018822U - High frequency conversion circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a high-frequency conversion circuit that is small and compact and can suppress an increase in manufacturing cost. In a high frequency conversion circuit having a high frequency carrier oscillator for converting an audio and video reproduced signal reproduced from a storage medium of a video recording device into a VHF band television signal, the high frequency carrier oscillator includes an LC lumped constant circuit and It is characterized in that it is a resonance circuit including a changeover switch for changing over a constant.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a high frequency conversion circuit capable of reducing expensive parts.

[0002]

[Prior art]

 FIG. 4 shows a conventional high-frequency conversion circuit (RF) for inputting and converting an audio signal and a video signal reproduced from a magnetic tape of a VHS type video tape recorder (VTR) device and outputting them to the television receiver. FIG. 3 is a circuit diagram showing the configuration of a converter). In the figure, 1 is an audio signal input terminal to which an audio signal reproduced from a magnetic tape is input by a VTR device (not shown), 2 is a video signal input terminal to which an reproduced video signal is input, and 3 is A control signal input terminal 4 to which a carrier wave off switch control signal sent from the control unit of the VTR device is input is a power supply terminal.

Reference numeral 5 is a filter circuit for an audio signal input from the audio signal input terminal 1, and 6 is a high frequency converter for converting an audio signal or a video signal reproduced from a magnetic tape of a VTR device into an NTSC system television signal. IC circuit of. The IC circuit 6 has an audio amplifier section 31 for amplifying an audio signal for the audio signal conversion, an audio signal FM modulating section 32 for FM modulating the audio signal and an audio carrier converting section 33, and converts the video signal. 2 has a high frequency carrier wave oscillator 7 for generating a carrier wave signal for frequency converting the video signal, a high frequency amplifier 8, a video signal converter 9, and a video clamp circuit 34 and a white clip circuit 35. Further, it has a carrier wave off switch 36 which operates by the control signal 3 and an antenna switch driver 37 which drives an antenna switch by its output. Reference numeral 10 denotes a channel switch, which switches the connection terminal of the SAW type resonator 11 connected to the high frequency carrier wave oscillator 7. The SAW resonator 11 is connected to the high-frequency carrier oscillator 7 by either the connection terminal 12a or the connection terminal 12b and the connection terminal 12c, and the carrier oscillation of the high-frequency carrier oscillator 7 depends on the position of the channel switch 10. Change the frequency.

Reference numeral 13 is an audio signal output terminal for outputting the converted audio signal, and 14 is a video signal output terminal for outputting the converted video signal. The converted audio signal and the video signal are combined. Then, the signal is supplied from the terminal 15 to the television receiver as a VHF band television signal of a predetermined channel of the television receiver through the filter circuit. Reference numeral 16 is a switching circuit for switching between an audio signal or a video signal reproduced by the VTR device and the antenna input from the antenna input terminal 17.

FIG. 5 shows a UHF band high-frequency conversion circuit, that is, a UHF band RF converter. FIG. 6 is a circuit diagram showing a configuration of a conventional high frequency conversion circuit to which a resonance circuit 21 capable of frequency converting a color signal of a video signal reproduced from a magnetic tape in a VTR device is connected. 5, those parts that are the same as those corresponding parts in FIG. 4 are designated by the same reference numerals, and a description thereof will be omitted. FIG. 6 is an electric circuit diagram showing the configuration of the resonance circuit 21. In order to change the output frequencies of the audio signal and the video signal, the resonance circuit 21 has a variable capacitor (variable capacitor) 22 for varying the resonance frequency of the resonance circuit 21. There is.

[0006]

[Problems to be solved by the device]

 Since the conventional high-frequency conversion circuit is configured as described above, the former high-frequency conversion circuit for the VHF band has a problem that the SAW type resonator 11 is expensive, which increases the manufacturing cost. The UHF band high-frequency conversion circuit is disadvantageous in terms of mounting pace because the frequency of the video signal is converted by a variable capacitor, and also has a problem of increased manufacturing cost.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-frequency conversion circuit that can be made compact by suppressing a mounting space and can suppress an increase in manufacturing cost.

[0008]

A high frequency conversion circuit according to the present invention has a high frequency carrier wave oscillator for converting audio and video reproduction signals reproduced from a storage medium of a video recording device into a VHF band television signal. In the high frequency conversion circuit, the high frequency carrier wave oscillator is a resonance circuit including an LC lumped constant circuit and a changeover switch for switching the constant.

The high-frequency conversion circuit according to the present invention is a high-frequency conversion circuit having a high-frequency carrier oscillator for converting audio and video reproduction signals reproduced from a recording medium of a video recording device into a UHF band television signal. The high-frequency carrier wave oscillator is characterized in that the capacitor of the resonance circuit for varying the carrier frequency is a trimmer capacitor.

[0010]

[Action]

 The high frequency conversion circuit according to the present invention converts the audio and video reproduction signals reproduced from the recording medium of a video recording device such as a video tape recorder device into an NTSC television signal of a VHF band, for example, an empty channel of 2 channels. , Output the output to the TV receiver. The SAW resonator becomes unnecessary.

Further, the high frequency conversion circuit in the present invention converts audio and video signals reproduced from a recording medium of a video recording device such as a video tape recorder device into a television signal channel in the UHF band, and outputs the output. Output to the receiver. No need for variable capacitors.

[0012]

【Example】

 First, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the VHF band high frequency conversion circuit of the first embodiment. In FIG. 1, parts that are the same as or correspond to those in FIG. 4 are assigned the same reference numerals and explanations thereof are omitted. In the figure, reference numeral 31 is an LC resonance circuit connected to the high frequency carrier wave oscillator 7, and its circuit configuration is shown in FIG. As shown in this figure, the LC resonance circuit 31 is composed of a coil L 1 and a coil L 2 connected in series, and a coil L 1 and a capacitor C 1 connected in parallel to the coil L 2 connected in series. It has a switch SW that can short-circuit both ends of L2.

In this LC resonance circuit 31, both ends of the coil L 2 are short-circuited or the short-circuited state is released by turning on or off the switch SW, the resonance frequency of the LC resonance circuit 31 changes, and the high-frequency carrier wave is changed. The carrier frequency of the oscillator 7 changes, and the same effect as when the carrier frequency of the high-frequency carrier oscillator 7 is changed by the channel switch 10 using the conventional SAW type resonator 11 can be produced, and the size and the size can be reduced. be able to. Further, since the component cost of the LC resonance circuit 31 is lower than that of the resonator 11, it contributes to the suppression of the manufacturing cost of the high frequency conversion circuit.

Next, a second embodiment of the high frequency conversion circuit of the present invention will be described. FIG. 3 is a partial circuit diagram in the vicinity of the high frequency carrier oscillator 7 of the VHS band high frequency converting circuit of the present embodiment, and the other circuit parts have the same configuration as FIG. In FIG. 3, the same parts as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. In the figure, reference numeral 41 is a resonance circuit connected to the high frequency carrier wave oscillator 7, and 42 is a trimmer capacitor such as a ceramic trimmer, which is advantageous in terms of mounting space and cost as compared with the variable capacitor 22 of FIG. This contributes to the miniaturization and compactness of the high frequency conversion circuit and the reduction of its manufacturing cost.

[0015]

[Effect of device]

 As described above, according to the present invention, the resonator connected to the high frequency carrier wave oscillator of the high frequency conversion circuit for generating the antenna input signal in the VHF band of the television receiver is constituted by the resonance circuit of the LC lumped constant circuit. A space-saving and high-priced SAW-type resonator is not required, and there is an effect that a high-frequency conversion circuit can be made compact and an increase in manufacturing cost can be suppressed.

According to the invention, the capacitor for varying the carrier frequency, which is connected to the high frequency carrier oscillator of the high frequency conversion circuit for generating the antenna input signal in the UHF band of the television receiver, is constituted by the trimmer capacitor. This eliminates the need for an expensive variable capacitor that has a large space, and has the effect of reducing the size of the high-frequency conversion circuit and increasing manufacturing costs. (Note) VHS is a registered trademark in the detailed description of the invention.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a high frequency conversion circuit for generating an antenna input signal in a VHF band according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an LC resonance circuit connected to a high frequency carrier oscillator of a high frequency conversion circuit for generating an antenna input signal in a VHF band according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a resonance circuit connected to a high frequency carrier oscillator of a high frequency conversion circuit for generating an UHF band antenna input signal according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a conventional high-frequency conversion circuit for generating a VHF band antenna input signal.

FIG. 5 is a circuit diagram showing a configuration of a conventional high frequency conversion circuit for generating a UHF band antenna input signal.

FIG. 6 is a circuit diagram showing a resonance circuit connected to a high frequency carrier oscillator of a conventional high frequency conversion circuit for generating an antenna input signal in the UHF band.

[Explanation of symbols]

 7 High Frequency Carrier Oscillator 31 LC Resonant Circuit 41 Resonant Circuit 42 Trimmer Capacitor

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[Procedure amendment]

[Submission date] June 5, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

Claims (2)

[Scope of utility model registration request] 1. A high frequency conversion circuit having a high frequency carrier oscillator for converting an audio and video reproduced signal reproduced from a storage medium of a video recording device into a VHF band television signal, wherein the high frequency carrier oscillator is an LC lumped constant circuit. A high-frequency conversion circuit, which is a resonant circuit including a switch for switching the constant. 2. A high frequency conversion circuit having a high frequency carrier oscillator for converting an audio and video reproduction signal reproduced from a recording medium of a video recording device into a UHF band television signal, wherein the high frequency carrier oscillator has a variable carrier frequency. The high-frequency conversion circuit is characterized in that the capacitor of the resonance circuit is a trimmer capacitor.