JPS6031129B2 - signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a signal processing device that outputs a signal with a desired time width;
In particular, it relates to a signal processing device that allows input signals to pass when they are not steep.

Conventional signal processing devices of this type reduce the time width of the output of the input amplifier circuit that activates the holding circuit, so that a hum component is superimposed on the output of the holding circuit, as will be explained in detail later using the drawings. However, as the rise of the input signal becomes slower, the output of the input amplifier circuit decreases by 4°, making the operation of the holding circuit uncertain and causing malfunction. Ta.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a signal processing device that does not malfunction even if an input signal has a slow rise.

According to the present invention, an amplifier circuit receives an input signal, a signal generating means receives the amplified output of the amplifier circuit and generates a desired signal, and prohibits generation of the amplified output of the amplifier circuit by the output of the signal generating means. There is obtained a signal processing apparatus characterized in that the signal processing apparatus further comprises means for positively feeding a change in the amplified output of the amplification circuit to the input of the amplification circuit.

A preferred example of the present invention described above includes an input amplifier circuit that amplifies an input signal received at its input and generates an amplified output when this input signal exceeds a certain input function value; A change in the output at the initial stage of amplification of the amplified output, for example, a feedback means configured to positively feed back a signal obtained by time-differentiating the output to the input amplifier circuit to produce a peak in the amplified output at that point, and a feedback means configured to generate a peak in the amplified output at that point, This is a holding circuit that receives the amplified output of the holding circuit and generates a holding output of approximately constant magnitude for an extended period of time. Another method is to feed back part of the holding output to the input amplification circuit to stop the input amplification action, or to cut off the circuit so that the subsequent signal of the input signal does not have an adverse effect on the holding circuit.
This is a signal processing device having two feedback means, whereby the waveform of the amplified output has an initial peak but has a short duration, and is made into a pulse shape, thereby reducing the held output within a short period of time. After reaching a constant value, the input signal is not affected by the amplified output of the input signal.

FIG. 1 is a diagram showing an example of a conventional signal processing device for an electronic contact switch.

That is, a commercial frequency AC voltage generated in the human body is applied to the input terminal 1 through the fingertip, and after passing through the reactor wave generator 5 consisting of resistors 2, 3 and a capacitor 4 to prevent malfunction due to external noise, the input amplifier circuit 6, the signal is amplified to an unnecessary level to trigger the holding circuit 7, and the holding circuit 7 is activated. However, if this continues, a hum component may appear between the output terminal 8 and the ground line (not shown) due to the output in the subsequent cycle, which may have a negative effect on devices using electronic switches (for example, a TV receiver). (The tuning frequency fluctuates due to the hum component and appears as a striped pattern on the screen.) As shown in the figure, can the output of the holding circuit 7 be fed back to the input amplifier circuit via line 9 to shut off the operation of the input amplifier circuit? Alternatively, it is common to cut off the signal transmission path and, after the holding circuit 7 is activated, to block further application of the output that is the amplified input signal. In this case, the return means comprising line 9 will be named first return means in contrast to the other return means described below. However, in this case, even if the circuit is cut off, the input signal must be applied for a certain period of time until the holding circuit 7 maintains the set state, so some delay element must be placed at an appropriate position in the circuit, for example. The holding circuit 7 is set by placing it at a feedback signal input section (not shown) of the input amplifier circuit 6. FIG. 2 is a diagram showing how hum occurs when the above-mentioned feedback is not applied, where a represents the input of the amplifier 6 (the dotted line is the input threshold value), and the solid line b represents the output of the amplifier 6. The dotted line represents the output when there is no feedback, the solid line c represents the time delay output, the dotted line represents the output when there is no feedback, the solid line d represents the output of the holding circuit 7, and the dotted line represents the output when there was no feedback. It represents the output.

The part indicated by the dotted line in d indicates the above-mentioned hum component, and the input signal indicated by the solid line in a is amplified as it is, and the current flows through the ground line and power supply line, resulting in an undesirable output. By applying feedback, the hum component is eliminated and an output of a constant value as shown by the solid line d is obtained. However, if the input signal has a slow rise, the time until the holding circuit 7 reaches the holding state will be delayed compared to when a rectangular wave is used as the input signal, especially if the rise is very slow. If the delay becomes large and exceeds the delay time of the delay element described above, there is a drawback that the holding circuit may malfunction.

If the delay time is lengthened to avoid this, the goal of this year, which is to stabilize the time delay output, will be hindered by that length, and if the delay time is left as is, the input signal with a gradual rise will be If the frequency is held constant, the operation in the case of a small input signal becomes uncertain, which is a major practical drawback.
In order to eliminate the above-mentioned drawbacks, in the present invention, even when the rise of the input signal is gradual, the input of the holding circuit, that is, the amplified output of the input amplifier circuit, rises steeply to ensure that the holding circuit operates in a short time. This is what I did.

FIG. 3 shows a signal processing device for an electronic contact switch according to the present invention, and the names and functions of the parts indicated by reference numbers 1 to 9 are substantially the same as in the conventional device shown in FIG. They are the same, and examples of the values for resistors and capacitors are also listed.

FIG. 4 is a diagram for explaining the operation of the device shown in FIG. 3 in comparison with the operation when there is no feedback. The explanation will be given below using both FIGS. 3 and 4. The feature of the configuration of the device of the present invention is that starting from the output point 10 of the input amplifier 6, a capacitor 1, a resistor 12, a branched and grounded resistor 13, and a capacitor 4' (shared with the component of the wave generator 5) are connected. (This portion of the circuit 14 will be referred to as the second feedback means in contrast to the first feedback means described above).

To explain the operation of the positive feedback circuit 14, when the input signal shown by the solid line that does not include the peak at e from the input terminal 1 exceeds the input threshold value (dotted line at e) of the input amplifier circuit 6, the output side, for example, 10 An amplified output (a waveform including a dotted line at 1) is generated, but since it suddenly increases from zero in the initial stage, the change is represented by the first peak of g differentiated by capacitor 11 and resistors 12 and 13. Such a differential signal (about 1 millisecond in this case) is added to the input signal via the capacitor 4. In this case, the direction is set to be positive feedback, resulting in a signal as shown by a solid line including a peak at e. Therefore, while this differential signal is superimposed, the amplified signal has an extremely large peak as shown by the solid line f, and therefore the output of the holding circuit 7 receives a complete rectangular wave as shown in i. It reaches a certain value in a short period of time similar to that when Note that h is a time delay output that will be explained later. Furthermore, since this peak-like output appears quite strongly even when the rate of change of the input signal level with respect to time is small, the holding circuit 7 can be stabilized very reliably and quickly even when the input signal is quite small. Furthermore, the differential signal that is fed back positively has only the AC component and the DC component is blocked, so it does not affect the DC operating point of the input circuit.
There is a large degree of freedom in designing the AC feedback loop. Now, considering the first feedback means previously explained in connection with the conventional example, for example, the input amplifier 6 learns the start-up time of the holding circuit 7 from the line 9, and uses a delay element (not shown) to determine the starting time as indicated by h'. If the holding circuit 7 is stopped at a time when the output of the holding circuit 7 becomes approximately constant, the holding circuit 7 will no longer be affected by hum caused by the input signal.

Moreover, since the time it takes for the output of the holding circuit 7 to become almost constant is short and stable, the selection of delay elements is easy and there is no risk of malfunction. Note that the delay element does not have to be provided in the input amplifier circuit, but may be provided separately in the middle of the line 9, and a special signal may be emitted through the line 9 when the output of the holding circuit 7 becomes stable. You may also do so. When using a plurality of input amplifier circuits and holding circuits, one of them should be configured to operate selectively, and the capacitor 4' of each input amplifier circuit should be connected to the second feedback means in the diagram at 15. All you have to do is connect them in common to the indicated parts.

However, in this case, it is necessary to set the amplitude of the differential pulse appropriately with respect to the input threshold of the input amplifier, and to take care not to operate other input amplifiers. In FIG. 3, the diode 17 connected to position 16 of the second feedback means is not necessarily required, but the input function of the input amplifier varies depending on the voltage between the base and emitter or between the anode and cathode of the semiconductor device. Temperature compensation can be performed on the amplitude of the differential pulse through 16 in such cases.

If you connect the base of a common emitter transistor to 16 instead of diode 17, you can achieve the same temperature compensation as above, and at the same time connect the collector of the transistor to other circuit parts, such as a TV. It is possible to extract an output pulse that causes the AFT default operation in the region.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional signal processing device, FIG. 2 is a diagram showing how a hum component is generated when the device in FIG. 1 does not apply feedback, and FIG. FIG. 4, which is a diagram showing an embodiment, is a diagram for explaining the operation of the apparatus shown in FIG. 3. Explanation of symbols: 5 is a wave generator, 6 is an input amplifier circuit, 7 is a holding circuit (signal generation means), 9 is a line (first feedback means), 1
4 respectively indicate second feedback means. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. An amplifier circuit that receives an input signal and generates an amplified output thereof; a holding circuit that is triggered by an output of a predetermined level or higher from this amplifier circuit to generate an output signal and maintains that state; and the output from this holding circuit. and means for inhibiting the generation of an amplified output of the amplifying circuit in response to a signal, the differentiating circuit detecting a change in the output of the amplifying circuit and positively feeding back the change to the input of the amplifying circuit. A signal processing device characterized by being provided with.