JPH09199964A - Signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a signal processor without dispersion in a frequency characteristic of an amplifier or the like due to a capacitance change by providing a signal processing means processing an input signal and a substrate capacitance detection means controlling the frequency characteristic of the signal processing means in response to a detected capacitance. SOLUTION: A substrate capacitance detection circuit 4 provides an output of a high control voltage Vc when the detected capacitance is small and provides an output of a low control voltage Vc when the detected capacitance is high. When the frequency characteristic of the amplifier 5 is changed due to the effect of the substrate capacitance, a variable equalizer 6 receives the control voltage Vc to correct a change in the frequency characteristic thereby obtaining the frequency characteristic suitable for the processing of a post-stage signal processing circuit 7. Thus, the signal processor without dispersion in the amplifier frequency characteristic due to a capacitance change is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing device including an amplifier circuit for performing processing for amplifying an image signal or the like.

[0002]

2. Description of the Related Art FIG. 6 shows a signal processing device in a conventional magnetic reproducing device such as a VTR. In FIG. 6, a video signal reproduced from a magnetic tape by a reproducing head (both not shown) is amplified by a head amplifier 1 and further equalized by a frequency characteristic by an equalizer 2, and then a video signal processing circuit 3
Is processed. Each of these circuits is formed on the same substrate. This substrate has a capacitance, and this capacitance varies depending on the substrate, but conventionally, the variation in the substrate capacitance was ignored and a constant capacitance was used.

[0003]

However, due to the recent increase in the density and the number of layers of substrates, the variation in the substrate capacitance is increased, which causes a change in the frequency characteristics of the amplifier circuit, etc., in view of the design of the signal processing circuit. I can't ignore it.

Therefore, the present invention provides a signal processing device in which variations in the substrate capacitance are detected and the frequency characteristics of the circuit are changed in accordance with the capacitance, so that there is no variation in the frequency characteristics of an amplifier or the like due to capacitance changes. To aim.

[0005]

SUMMARY OF THE INVENTION In the present invention, a signal processing means configured on a substrate for processing an input signal and having variable frequency characteristics, and a capacitance of the substrate are detected, and the detected capacitance is set to the detected capacitance. Correspondingly, a substrate capacitance detecting means for controlling the frequency characteristic of the signal processing means is provided.

[0006]

According to the present invention, the signal processing means receives the control voltage from the substrate capacitance detecting means and corrects the frequency characteristic, whereby the frequency characteristic suitable for the signal processing in the subsequent stage can be obtained.

[0007]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, reference numeral 4 denotes a substrate capacitance detection circuit, which outputs a high control voltage Vc when the detected capacitance is small and outputs a low control voltage Vc when the detected capacitance is large. In the present embodiment, when the amplifier 5 is affected by the substrate capacitance and the frequency characteristic is changed, the variable equalizer 6 receives the control voltage Vc to correct the change in the frequency characteristic, and the signal processing at the subsequent stage is performed. The frequency characteristic suitable for the processing of the circuit 7 is obtained.

As a result, it is possible to provide a signal processing device in which variations in the amplifier frequency characteristics due to capacitance changes do not occur. In the present embodiment, the amplifier 5 and the variable equalizer 6 constitute a signal processing means.

FIG. 2 shows a second embodiment of the present invention.
In the figure, reference numerals 8a and 8b denote dummy patterns for capacitance testing written on the substrate, which are laid out so as to have capacitance between layers on the substrate. One dummy pattern 8
The switch 9 connected to a is controlled by the control pulse 11 from the microcomputer 10 and connected to the side a for a certain period of time, so that the output of the charging circuit 12 is set to the dummy pattern 8
The capacity of a and 8b is charged. Next, switch 9
It is switched to the side and connected to the high impedance buffer 13 to discharge the above capacity.

This discharge output changes the discharge time according to the change in capacity. The board capacitance is detected by counting the time until the discharge output reaches the threshold level in the microcomputer 10. As a result, when the capacity is small, the above time is short, so at that time the microcomputer 1
A high control voltage Vc from 0 is output to the variable equalizer 6. When the capacitance is large, the above time is long, and at that time, the low control voltage Vb is output to the variable equalizer 6. As shown in FIG. 4, the variable equalizer 6 is controlled by the control voltage Vc to change the frequency characteristic, and is configured to correct the frequency characteristic suitable for the video signal processing circuit 3 connected in the subsequent stage. There is.

As a result, the variable equalizer 6 corrects the variation in the reproduction RF output due to the change in the capacitance, so that the magnetic reproducing apparatus with less variation can be provided. FIG.
In FIG. 1, the substrate capacitance detection circuit 4 of FIG.

FIG. 3 shows a third embodiment of the present invention.
In the figure, the oscillator 1
The filter is equivalently configured by inputting the output of 4 with a constant impedance through the impedance converter 15. The filter output is amplified by the amplifier 16 and the level is detected by the wave detector 17. The detection output is such that the detection voltage changes according to the capacitance change. This detection output is used as a control voltage Vc for the variable equalizer 6
Is controlled to correct the frequency characteristic as shown by the equalizer characteristic in FIG. As a result, the frequency characteristic of the output of the head amplifier 1 is corrected, and the frequency characteristic suitable for the video signal processing circuit 3 connected thereafter can be obtained.

As a result, it is possible to provide the magnetic reproducing apparatus with less variation by correcting the variation of the reproduction RF output due to the change in capacity with the equalizer. Note that, in FIG. 3, the substrate capacitance detection circuit 4 is configured by each unit of 14 to 17. 2 and 3, the head amplifier 1 and the variable equalizer 6 constitute a signal processing means.

FIG. 5 shows a fourth embodiment of the present invention.
In the figure, when the head amplifier 1 is affected by the substrate capacitance and its frequency characteristic changes, the head amplifier 1 receives the control voltage Vc from the substrate capacitance detection circuit 4 for correction due to the secondary resonance of the head amplifier 1. This corrected output is sent to the video signal processing circuit 3 through the RF equalizer 2. Therefore, the frequency characteristic suitable for the video signal processing can be obtained. As a result, it is possible to provide the magnetic reproducing apparatus in which the frequency characteristic of the head amplifier does not vary due to the capacitance change. In FIG. 5, the head amplifier 1 constitutes a signal processing means.

[0015]

As described above, according to the present invention, the fact that the frequency characteristic of the signal processing means changes due to the influence of the substrate capacitance is corrected by receiving the control voltage from the substrate capacitance detecting means. As a result, it is possible to obtain a frequency characteristic suitable for signal processing in the subsequent stage, and it is possible to provide a signal processing device in which there is no variation in frequency characteristic of an amplifier or the like due to capacitance change. Then, it is possible to provide a signal processing device that copes with variations in substrate capacitance due to the recent increase in the density and the number of layers of substrates.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a characteristic diagram of the variable equalizer used in the first to third embodiments.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional signal processing device.

[Explanation of symbols]

 1 Head amplifier 4 Substrate capacitance detection circuit 5 Amplifier 6 Variable equalizer

Claims (3)

[Claims] 1. A signal processing means configured on a board for processing an input signal and having variable frequency characteristics, and a frequency characteristic of the signal processing means for detecting the capacitance of the board and depending on the detected capacitance. And a substrate capacitance detecting means for controlling the signal processing device. 2. The signal processing means comprises an amplifier circuit for amplifying the input signal, and a variable equalizer circuit to which the amplified output is input and which is controlled by the substrate capacitance detecting means. The signal processing device according to claim 1. 3. The signal processing means is configured to include an amplifier circuit which amplifies the input signal and whose frequency characteristic is controlled by the substrate capacitance detecting means. Signal processing device.