JPH0247640Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an input selection device suitable for input selection of a television receiver or the like.

BACKGROUND ART When a plurality of external devices such as a video tape recorder and a video disc player are connected to a television receiver, selection switches corresponding to the number of external devices are required to select the source to be viewed. However, it would be expensive to manufacture switches for each television receiver for the number of external devices that are expected to be connected. The numerical value may be increased or decreased so that an external device is selected according to the output of the counted value.

However, the conventional input selection device using this type of ring counter is difficult to use as the number of external devices used increases. In this case, the number of times the selection switch must be pressed before the antenna input is selected increases, resulting in a disadvantage that the viewer is more likely to feel inconvenienced.

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, and comprises a ring counter by connecting a decoder circuit and a preset value input circuit to a counter circuit, and a sequential selection switch connected to the clock input terminal of the counter circuit. It is an object of the present invention to provide an input selection device that can sequentially select a plurality of inputs and also independently select a specific input by using an independent selection switch connected to a clear input terminal of a counter circuit.

To achieve this object, the present invention provides a counter circuit having a clock input terminal, a clear input terminal, a load input terminal, a preset value input terminal and a count value output terminal, and a count value output of the counter circuit. a decoding circuit that decodes a preset value input terminal and outputs an input selection signal according to the decoding result, and also supplies one decoding result to a load input terminal; a preset value input circuit that operates to input a preset value to the counter circuit; a sequential selection switch that is connected to the clock input terminal and supplies a clock input each time it is operated to change the count value of the counter circuit;
The main feature is that the switch is connected to a clear input terminal and is configured with an independent selection switch that resets the count value of the counter circuit to zero each time it is operated.

According to the present invention, a ring counter is constructed by connecting a decoder circuit with a decoding output corresponding to the number of inputs to be selected and a preset value input circuit to a counter circuit. By operating the connected sequential selection switch, the counter circuit can cycle through and count up to a predetermined value corresponding to the preset value and the number of inputs, and can sequentially output the signals necessary for input selection as selection output. In addition, by operating the independent selection switch connected to the clear input terminal of the counter circuit, the count value of the counter circuit is reset to zero regardless of the sequential selection output, and a predetermined specific input is selected by the independent selection output. Therefore, a ring counter configured using a counter circuit with a clear input terminal provides excellent effects such as the ability to easily realize sequential selection of a plurality of inputs and independent selection of specific inputs.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are a schematic circuit diagram showing an embodiment of a television receiver to which the input selection device of the present invention is applied, and a circuit diagram showing an embodiment of the input selection device, respectively.

In FIG. 1, an input selection device 1 is incorporated in the front panel of a television receiver 2, and a signal input circuit 3 into which a plurality of television signals are input.
It is connected to. The signal input circuit 3 is connected to a television antenna 4 that receives television broadcast signals and n external devices 5 ₁ to 5 _o as other video sources, and among the n+1 types of signal inputs,
Depending on the selection signal from the input selection device 1, one of the signal inputs is selected. Therefore, the signal input circuit 3 includes an antenna input selection terminal 30 for selecting an antenna input as a specific input, and n external input selection terminals 3 for selecting external inputs as multiple inputs.
₁ to 3 _o are provided.

As shown in FIG. 2, the input selection device 1 has a counter circuit 6 consisting of a 4-bit up counter, and the counter circuit 6 has a clock input terminal 6a, a clear input terminal 6b, and a load input terminal 6c.
A sequential selection switch 7, an independent selection switch 8, a decoder circuit 9, and a preset value input circuit 10 are connected to the preset value input terminal 6d, and the count value output terminal 6e of the counter circuit 6 is connected to the decoder circuit. 9 is connected. The decoder circuit 9 has n+2 output terminals ₉₀ to 9o ₊₁ , which is one more than the n+1 types of signal inputs, and converts the binary count value output of the counter circuit 6 into a decimal number. Output terminal 9 with the same subscript as the value
A selection signal is output from ₀ to 9 _o+1 . In the case of this embodiment, the output terminal ₉₀ is connected to the antenna input selection terminal ₃₀ ,
Further, the output terminals 9 ₁ to 9 _o are connected to the external input selection terminals 3 ₁ to 3 _o corresponding to the subscripts, and the last remaining output terminal 9 _o+1 is connected to the load input terminal 6 c of the counter circuit 6. There is. This load input terminal 6c
is supplied with a signal (the decoding result of 1) from the output terminal 9 _o+1 , and serves as an input terminal for causing the counter circuit 6 to read a preset value preset in a preset value input circuit 10, which will be described below.

The preset value input circuit 10 includes a counter circuit 6
In this embodiment, the preset value input circuit 10 is preset with 0001 as the preset value. Therefore, when a signal is supplied to the aforementioned load input terminal 6c, the counter circuit 6 receives the preset value from the preset value input circuit 10.
0001 is read, and as a result, counter circuit 6
will start counting again from count value 0001. That is, in a normal counting operation, the counter circuit 6 starts with a preset value of 0001, and returns to the starting value of 0001 after n counting operations.
It performs so-called cyclic counting, thereby functioning as a ring counter.

By the way, as mentioned above, the sequential selection switch 7
is connected to the clock input terminal 6a of the counter circuit 6, so that each time the selection switch 7 is sequentially closed, a clock pulse is supplied to the clock input terminal 6a. Therefore, the counter circuit 6
counts up by adding 1 to its count each time it is supplied with a clock pulse.

On the other hand, the independent selection switch 8
The clear input terminal 6b of the counter circuit 6 is connected between the clear input terminal 6b and ground, and therefore, by closing the independent selection switch 8, the clear input terminal 6b is grounded and the count value of the counter circuit 6 is cleared. As a result, the count value of the counter circuit 6 is reset to zero and set to 0000.

In this embodiment, both the sequential selection switch 7 and the independent selection switch 8 are of push button type.

Now, if you want to select a desired video source from among the n external devices 5 ₁ to 5 _o , sequentially press the selection switch 7 until the external device 5 ₁ to 5 _o corresponding to the desired video source is selected. Press several times. When the sequential selection switch 7 is pressed once, the count value of the counter circuit 6 is incremented by 1, and at the same time, external input selection signals are sequentially obtained from the output terminals 9 ₁ to 9 _o+1 of the decoder circuit 9. As mentioned above, all of these external input selection signals are obtained by the counter circuit 6 counting n times, so by pressing the selection switch 7 sequentially n times even if the number is n, the external input selection signal can be selected from the external device corresponding to the desired video source. 5 ₁ to 5 _o ,
You can always choose. Strictly speaking, the number of times the sequential selection switch 7 must be pressed before the desired external device is not selected as an input to the television receiver 2 is the
It is determined by the difference in the subscripts between ₁ to 5 _o and the desired external device 5 ₁ to 5 _o .

In this way, when selecting an external input other than the antenna input, the selection switch 7 can be pressed an appropriate number of times in sequence, but when selecting the antenna input, the independent selection switch 8 can be pressed. When the independent selection switch 8 is pressed, the counter circuit 6 erases the previous count value and changes it to a count value of 0000.
As a result, the output of the decoder circuit 9 becomes 0, and the antenna input selection signal is supplied to the signal input circuit 3 from the output terminal ₉₀ .

That is, when it is desired to display a television broadcast signal on the screen of the television receiver 2, by pressing the independent selection switch 8, the signal is displayed immediately regardless of the currently selected external device ₅₁ to _5o . The antenna input can be the input of the television receiver 2.

As explained above, according to the input selection device 1 having the above configuration, the decoder circuit 9 having decoding outputs corresponding to the number of inputs to be selected and the preset value input circuit 10 are connected to the counter circuit 6. Since the ring counter is configured as a ring counter, by operating the sequential selection switch 7 connected to the clock input terminal 6a of the counter circuit 6, the counter circuit 6 cycles through a predetermined value corresponding to the preset value and the number of inputs. The signals necessary for input selection can be sequentially output as selection outputs. In addition, the clear input terminal 6b of the counter circuit 6
By operating the independent selection switch 8 connected to , the count value of the counter circuit 6 can be reset to zero regardless of the sequential selection output, and a predetermined specific input can be selected by the independent selection output. That is, the ring counter configured using the counter circuit 6 with the clear input terminal 6b is used as a main component, and the sequential selection of a plurality of inputs and the independent selection of specific inputs can be easily realized.

[Brief explanation of the drawing]

1 and 2 are a schematic circuit diagram showing an embodiment of a television receiver to which the input selection device of the present invention is applied, and a circuit diagram showing an embodiment of the input selection device, respectively. 1... Input selection device, 2... Television receiver,
3...Signal input _circuit , ₃₀ ...Antenna input selection terminal, _31-3o ...External input selection terminal, 4...TV antenna, _51-5o ...External device, 6...Counter circuit, 6a...Clock input terminal, 6b ...Clear input terminal, 6c...Load input terminal, 6d...Preset value input terminal, 6e...Count value output terminal, 7...Sequential selection switch, 8...Independent selection switch, 9...Decoder circuit, ₉₀ to 9 _o+1 ... Output terminal, 10...Preset value input circuit.

Claims (1)

[Scope of utility model registration request] A counter circuit having a clock input terminal, a clear input terminal, a load input terminal, a preset value input terminal, and a count value output terminal, and a count value output of the counter circuit is supplied, the count value output is decoded, and the count value output is decoded according to the decoding result. a decoder circuit that outputs a selected input selection signal and supplies one decoding result to the load input terminal; and a decoder circuit connected to the preset value input terminal and operating together with supplying one decoding result to the load input terminal; a preset value input circuit that inputs a preset value to the counter circuit; a sequential selection switch that is connected to the clock input terminal and supplies a clock input every time it is operated to change the count value of the counter circuit; and the clear input. An input selection device comprising an independent selection switch connected to a terminal and resetting the count value of the counter circuit to zero each time it is operated.