JPS5927491B2 - Converter for television signal reception - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television signal receiving converter that can receive all television broadcasts from VHF (5UHF and, if necessary, up to SHF band) by simply operating this unit.
In particular, during channel selection, the operation of the converter is stopped until a desired channel is selected, thereby temporarily placing the television receiver in a no-signal receiving state.

This television signal reception converter converts all channels of television broadcast to any channel in any television broadcast wave band (this is preferably an empty channel that is less than 10 channels that are not being broadcast in the receiving area). For example, if the VHF third channel is an empty channel, the UHF in this converter
The frequency bands of all channels received by the tuner and VHF tuner are converted into the frequency band of the third channel (video carrier wave 15
103.25MH2) Audio carrier wave 107.75M[l2
), and by connecting it to the antenna terminal of an existing television receiver, it is possible to receive all UHF and VHF channels, even in a television receiver dedicated to receiving the VHF band, for example.

20 By the way, if you use a new type of converter, even if the connected television receiver has a rotary operation type channel selection mechanism based on the successor of the old model, it will be possible to switch between push button type, touch type, or channel selection depending on the converter. Furthermore, although it is possible to receive each channel on 25 using a simple channel selection operation such as a remote control, in this case, the audio and video of other stations may be heard on the television until the desired channel is selected. There was a shortcoming that appeared momentarily on the machine.

The present invention has been made in view of these points.
The present invention provides a television signal receiving converter that can temporarily stop its output when selecting a channel.

The present invention will be described below with reference to embodiments shown in the drawings.

35 Figure 1 shows a channel selection device using the converter according to the present invention in a block diagram, where 1 indicates VHF.
Antenna, 2 is a UHF antenna, 3 is a converter that is particularly related to the invention of A. Hermitage, 4 is a normal television receiver, and the converter 3 includes a channel selection circuit 5, a muting circuit 6, a band switching circuit 7, It is composed of a frequency conversion circuit 8.

Taking as an example the case where it operates as a push-button channel selection device, the following description will begin by first pressing any one of the channel selection switch group 9.
When one switch is pressed, the tuning circuit 5 is operated and the pressed station is selected.

At the same time as this channel selection, the band switching circuit 7 operates to determine whether the selected station is a VHF low channel, UHF Haitian channel, or UHF channel, and the band switching voltage (BL, BH) of the receiving station is determined. , Bu) are applied to the frequency conversion circuit 8. At the same time, the channel selection circuit 5
A tuning voltage corresponding to the tuned channel is applied to the frequency conversion circuit 8, and at this time, the frequency conversion circuit 8 outputs the tuning voltage corresponding to the tuning channel of the television receiver 4 (for example, the third VHF channel). The output converted into a frequency is taken out, and this output is supplied from the antenna terminal of the television receiver 4 to the tuner. Note that during this tuning, one pulse is output from the tuning circuit 5, and this pulse operates the muting circuit 6, and the output of the band switching circuit 705 is stopped for a certain pulse period determined by this circuit 6. Ru. Therefore, since the band switching output is not derived for a certain period of time after tuning, the operation of the frequency conversion circuit 8 is stopped during this period, and the output of the circuit 8 is temporarily in a no-signal state. That is, in this frequency conversion circuit 8, the band switching voltages (BL, BH, Bu) are used to drive the RF amplification stage, local oscillation stage, mixing stage, etc. in the frequency conversion circuit 8, as in the case of conventional general television tuners. Since it is supplied as a power supply voltage, when no band switching voltage (BL, BH, Bu) is currently supplied from the band switching circuit 7, the operation of the frequency conversion circuit 8 is stopped, and during this period, its output is in a no-signal state. Become. Thereafter, after a certain period of time has elapsed, the band switching output is derived again and the operation of the frequency conversion circuit 8 is restarted. Note that the output pulse time of the muting circuit 6 is the time required for the tuning voltage of the selected channel to be correctly applied to the frequency conversion circuit 7, for example, 0.
．． It may be set to about 0.05 to 0.2 seconds. In this way, according to the converter of this embodiment, the band switching output is temporarily lost when selecting a channel as described above, and the operation of the frequency conversion circuit is stopped during this time, so that the television receiver momentarily displays a no-signal noise screen when selecting a channel. Therefore, the video and audio of other stations will not be displayed in a lewd manner.

FIG. 2 shows an example of a circuit configuration diagram that further embodies the muting circuit 6 and band switching circuit 7 in FIG. 1.

At this point, when the channel switching operation is not performed and the previous receiving station is being continuously received, the transistor Q5 of the tuning circuit 5 is in the off state, so the transistor Q1 of the muting circuit 6 is also in the off state. .

Therefore, at this time, diodes Dl, D2, and D3 are all in the cut-off state. If the VHF low channel is being received at this moment, in the band switching circuit 7, only the transistor Q2 is in the on state based on the output VL (L level) of the band switching circuit 10, and the other transistors Q3 and Q4 are in the off state. state. Therefore, at this time, approximately the power supply voltage +B is output as the band switching output BL, and the other outputs BH and BL are 0 (V). When the channel is then switched to, for example, another VHF low channel, a positive channel switching pulse is applied to the base of the transistor Q5 of the tuning circuit 5, thereby turning on the transistor Q5.

When the transistor Q5 is turned on, the transistor Q of the muting circuit 6 is also turned on, and even if the transistor Q5 is turned off thereafter, the resistors Rl and R2 are turned on.
The on state is maintained for, for example, 0.05 to 0.2 seconds while the capacitor C1 is charged with a time constant determined by the capacitor C1, etc., and then the transistor Q1 is again cut off. Therefore, even if the L output (L level) of the band changeover switch circuit 10 is derived at this time, the diode D is in an on state during this time, and therefore the transistor Q
2 is temporarily cut off, and the band switching output BL is no longer derived. Of course, at this time the other transistor Q
3. Q4 is in cut-off state and band switching output BH,
Bu is also not derived and is at L level. However, after a certain period of time has elapsed, the transistor Q1 is cut off and the diode D1 is turned off, so the transistor Q2 is turned on again and the band switching output BL is derived.
In this way, when switching from the HF low channel to another low channel, the band switching output VL temporarily disappears, that is, it temporarily changes from the H level to the L level, and then returns to the H level.
However, when switching from VHF low channel to HF Haiti channel or UHF channel, or vice versa, the band switching outputs BL and B are operated in the same way.
H, Bu temporarily disappear, and during this time each output BL, BH
, Bu are both at L level.

FIG. 3 shows a circuit configuration diagram of another embodiment, in which the power supply voltage +B for circuit driving is supplied to the band switching circuit 7 through the transistor Q of the muting circuit 6. Here, when a negative polarity channel switching panel is supplied to the base of the transistor Q5 of the tuning circuit 5 during tuning, the transistor Q5, which is normally in an on state,
Both Ql are in the cut-off state only during this period, and the supply of power supply voltage +B to the band switching circuit 7 is temporarily stopped.
Band switching outputs BL, BH, and BU are no longer derived.

During the other periods, the transistor Q1 is turned on, and the power supply voltage +B is supplied to the band switching circuit 7 through the transistor Q1. transistor Q2,
Either one of Q3 and Q4 is turned on, and band switching outputs BL, BH, and Bu are derived.

As a result, the output of the frequency conversion circuit 8 in FIG. 1 temporarily becomes a no-signal output state when selecting a channel.

According to the television signal receiving converter of the present invention,
When selecting a station, the band switching output is stopped for a certain period of time and the frequency conversion circuit is in a no-signal output state, so the television receiver connected to the converter at this time displays a no-signal noise screen, and when selecting a station, the frequency conversion circuit outputs no signal. No video or audio is derived. Furthermore, in the present invention, since the band switching output is stopped when selecting a station, even if preset selection of 8 to 12 stations is possible, the converter can be easily and reliably activated by simply controlling the three band switching outputs BL, BH, and BU. It can be in a no-signal output state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a channel selection device using the converter of the present invention, and FIGS. 2 and 3 are circuit configuration diagrams embodying the main parts of the converter in FIG. 1. 3...Converter, 6...Mutating circuit, 7...Band switching circuit, 8...
...Frequency conversion circuit.

Claims (1)

[Claims] 1 In a converter that receives television signals in multiple broadcast wave bands such as VHF and UHF and converts them to the frequency of a specific station, there is a muting circuit that is driven based on a channel switching signal when selecting a channel, and the output of the muting circuit. a band switching circuit in which band switching output is stopped based on;
A frequency conversion circuit that converts a received signal into a specific frequency signal based on the band switching output and a tuned tuning voltage, and temporarily puts the output of the frequency conversion circuit in a no-signal output state when selecting a station. A converter for television signal reception featuring: