JPS5850396B2 - signal selection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal selection circuit for causing one counter to perform two counts.

For example, when displaying the remaining amount of tape on a partially used tape in a tape recorder, etc., the remaining amount of tape at the current position must be counted and displayed immediately when the tape is loaded into the tape recorder and the tape begins to drive. After that, the amount of remaining tape must be displayed as it changes every moment as the tape runs.

It is not a good idea to perform the above two counts using different counters, but if one counter is used and two different signals are converted into the same state and applied to the counter, The circuit can be simplified.

The present invention has been made to achieve the above-mentioned objects.
Hereinafter, an explanation will be given based on an example with reference to the drawings.

The figure is a circuit diagram showing an embodiment of the signal selection circuit according to the present invention, in which 1 is a counter for counting the number of input pulses, and 2 is a circuit diagram for selecting the input pulse to be applied to the counter 1. a signal selection circuit; 3 an oscillator that generates a reference signal; 4 a pulse generation circuit that generates a pulse with a changing period; 5 a gate circuit that generates a gate signal based on the period of the pulse;
is a switching signal generation circuit that generates a switching signal for switching the signal selection circuit 2 to the first state or the second state, and the signal selection circuit 2 has a three-manpower NAND circuit and a two-manpower NAND circuit.
AND circuit 8, two-man OR circuit 9, and inverter 10
It consists of

Therefore, the first input terminal A of the three-person NAND circuit 7
is connected to the oscillator 3, the input terminal B is connected to the gate circuit 5, and the input terminal C is connected to the switching signal generation circuit 6 via the inverter 10.

Further, the blade terminal A of the two-man power NAND circuit 8 is connected to the switching signal generation circuit 6, the input terminal B is connected to the pulse generation circuit 4, and the output terminal of the three-man power NAND circuit 7 is connected to the two-man power OR.
The input terminal A of the circuit 9 is connected to the output terminal C of the two-man power NAND circuit 8, and the output terminal C of the two-man power NAND circuit 8 is connected to the input terminal B of the OR circuit 9.

Furthermore, the output terminal C of the two-person OR circuit 9 is connected to the input terminal of the counter 1.

If counting is to be performed for initial value setting, the switching signal generation circuit 6 generates an "L" signal, and the signal selection circuit 2 enters the first initial value setting state.

The switching signal generation circuit 6 has a built-in counter and is configured to count the output pulses of the pulse generation circuit 4 and generate the rLJ signal only during the first few pulses, and thereafter generate the "H" signal. ing.

When the rLJ signal is generated from the switching signal generation circuit, the rHJ signal is applied to the input terminal G of the three-man power NAND circuit T via the inverter 10.

Further, the gate circuit 5 generates a gate signal according to the period of the output pulse of the pulse generating circuit 4, and the oscillator 3 generates a repetitive pulse of a constant frequency.

The period of the output pulse of the pulse generating circuit 4 varies depending on the position of the detected object (tape in the case of a tape recorder),
Therefore, the "H" period of the gate signal also differs depending on the position of the object to be detected.

Therefore, the number of repetitive pulses of the oscillator 3 corresponding to the gate period of the gate signal also differs.

When the object to be detected is set and the first pulse is generated from the pulse generating circuit 4, the gate signal of the gate circuit 5 becomes "H" for a predetermined period until the second pulse is generated, and the three-man power The rHJ signal is applied to the input terminal B of the NAND circuit 1.

Therefore, input terminals B and C of the three-person NAND circuit I
Since the “H” signal is applied to the input terminal A
The three-person NAND circuit 7 is activated only when the “H” signal is input to
generates an "L" signal.

At that time, the input terminal A of the two-person NAND circuit 8 has rLJ.
Since the signal continues to be applied, no matter which output signal "H" or rLJ of the pulse generation circuit 4 is applied to the input terminal B, the output terminal C of the two-man power NAND circuit 8 receives rHJ.
The signal continues to occur.

Therefore, the rHJ signal is generated at the output terminal C of the OR circuit 9 only when the l'-HJ signal is applied to the input terminal A of the OR circuit 9, and each time the rHJ signal is applied, the counter 1 advances.

The number of times the output signal of the OR circuit 9 becomes "H" is the number of times the output signal of the oscillator 3 becomes "H" during the period when the output signal of the gate circuit 5 is rHJ.
is equal to the number of pulses generated from .

Therefore, the counter 1 can count a number depending on the position of the object to be detected. For example, in the case of a tape recorder, a number related to the remaining amount of tape is counted.

The above-mentioned counting is repeated until the number of pulses applied from the pulse generating circuit 4 to the switching signal generating circuit 6 reaches a predetermined number (for example, four), and an accurate value is counted.

When the initial value setting is completed, the output signal of the switching signal generation circuit 6 automatically becomes "H" due to the action of the built-in counter, and the signal selection circuit 2 enters the second pulse counting state.

Therefore, the rLJ signal is applied to the input terminal C of the three-man power NAND circuit 7 via the inverter 10, and the three-man power NAND circuit I outputs "H" to its output terminal regardless of the signals applied to the input terminals A and B. ” Derive the signal.

On the other hand, since the "H" signal continues to be applied from the switching signal generation circuit 6 to the input terminal A of the two-man power NAND circuit 8,
A pulse is generated from the pulse generation circuit 4 and sent to the input terminal B.
An rLJ signal is generated at the output terminal C of the input NAND circuit 8 every time the "H" signal is applied.

Therefore, the rHJ signal continues to be applied to the input terminal A of the OR circuit 9, and the rLJ signal is applied to the input terminal B every time an output pulse of the pulse generation circuit 4 is generated. An rHJ signal is generated every time an output pulse of the pulse generating circuit 4 is generated, and is applied to the counter 1 to perform increment.

Therefore, the counter 1 performs counting by adding or subtracting a signal generated every time a pulse is generated to an initial value counted previously in accordance with the movement of the object to be detected.

As described above, the input signal of the counter 1 can be converted into the same type of signal in both the initial value setting state and the pulse counting state by using the signal selection circuit 2 related to this generation. It has the advantage that it can be shared and counting can be done easily.

In the embodiment, the case of a tape recorder is taken as an example, but the invention is not limited thereto, and the present invention is effective in various cases where two different signals are counted.

[Brief explanation of the drawing]

The figure is a circuit diagram showing one embodiment of the present invention. Explanation of main figure numbers, 1... Counter, l...
・Signal selection circuit, 3...Oscillator, 4...
・Pulse generation circuit, 5...Gate circuit, 6...
...Switching signal generation circuit, 7...3 manual NA
ND circuit, 8...2-manpower NAND circuit, 9...
...2-person OR circuit, 10...inverter.

Claims (1)

[Claims] 13 A human-powered NAND circuit, a two-human powered NAND circuit, the output signal of the three-human powered NAND circuit, and the output signal of the two-human powered NAND circuit are two-human powered, and when the input is rLJ, the output rHJ is When the output becomes “H”, the output “L”
” and a logic circuit that generates
a first input terminal of the circuit and a first input terminal of the three-way NAND circuit;
An output terminal of a switching signal generation circuit that outputs a signal in a first state ("L" or "H") or a second state ("H" or "L") is connected to the input terminal. When the state output signal is output, the first input terminal of the two-man power NAND circuit becomes "L", the first input terminal of the three-man power NAND circuit becomes rHJ, and the second state output signal is output to the output terminal. When the two-man power NAND circuit is connected, the first input terminal of the two-man power NAND circuit is "H" and the first input terminal of the three-man power NAND circuit is rLJ.
The second input terminal of the circuit is connected to the output terminal of a pulse generation circuit that generates a pulse whose period changes according to the detected value, and the second input terminal of the three-man power NAND circuit is connected to the output terminal of the pulse generation circuit. The output terminal of a gate circuit that is connected to the output and creates a gate signal according to the period of the output pulse is connected, and the third input terminal of the three-man power NAND circuit is connected to the output terminal of an oscillator that outputs a pulse signal of a constant period. and a counter is connected to the output terminal of the logic circuit, and when the output signal of the switching signal generation circuit is in a first state, a pulse from the oscillator is generated during the existence period of the gate signal. A signal selection circuit, characterized in that a signal is applied to a counting circuit, and when the output signal of the switching signal generation circuit is in a second state, the output signal of the pulse generation circuit is applied to the counting circuit.