JPH0514732A - Binarizing device - Google Patents

Abstract

PURPOSE:To reduce the oversight of a detection signal due to the variation of a level by making the reference signal of a binarizing device the envelope of an output signal. CONSTITUTION:The video output S0 of a CCD camera 1 is made into an envelope curve S1 by passing it through a low pass filter (LPF) 2, and is outputted from the LPF 2. This signal S1 is made into the signal S2 by correcting its loss by the LPF 2 by an amplifier (AMP) 3, and is inputted to the reference input terminal R of a comparator (CMP) 4. In the CMP 4, it is outputted as the output signal S3 corresponding to difference between the signal S2 inputted to the terminal R and the signal S0 inputted to the terminal S. The signal S3 detects the signal of different absolute level on the envelope curve of the former video signal S0 without overlooking it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binarizing device, and more particularly to a binarizing device for an output signal of a one-dimensional CCD camera.

[0002]

2. Description of the Related Art FIG. 3 shows a block diagram of a signal processing unit of a conventional one-dimensional CCD camera. In FIG. 3, the output V ₀ of the CCD camera 1 is input to the signal input terminal S of the comparator 4. Further, a constant voltage V _ref is input to the reference input terminal R of the comparator 4.

The comparator 4 binarizes the output of the CCD camera 1 by comparing the R input and the S input (for example, "Video sensor introduction guide" S63.
P. 41-, P.I. 232 ...). Here, the reference voltage V _ref of the comparator 4 is _generated by dividing the constant voltage V _c by the variable resistor 5.

In actual use, the resistance value of the variable resistor 5 is changed according to the situation of the video signal to find a satisfactory position on average.

[0005]

The conventional one-dimensional CC
FIG. 4 shows an operation state of the binarizing device of the D camera. The output signal V ₀ of the one-dimensional CCD camera 1 often has an envelope curve as shown in FIG. 4A due to uneven illumination of the subject. In this gentle envelope curve, the signals to be originally detected, that is, the dips D ₁ and D _{2 in} the example of this figure are superimposed.

When such a signal is sliced at a constant voltage V _{ref and} binarized as in the conventional example, the signal to be originally detected may be overlooked.

FIG. 4 shows such a case. That is, FIG. 4B shows the result of binarization when V _ref = T ₁ in FIG. 4A, but the dip D ₁ is missed.

In the case of FIG. 4C, the binarization is performed with V _ref = T ₂ , but the dip D ₂ is missed as shown in FIG. 4D. In the case of this example, since the envelope curve has a steep inclination, both dips D ₁ and D ₂ cannot be detected correctly. That is, in the related art, when the subject illumination is non-uniform, the reference voltage is uniquely determined, and thus there is a problem that a signal to be originally detected may be missed.

It is an object of the present invention to provide a binarization device that solves the above problems.

[0010]

In order to achieve the above object, in a binarizing device according to the present invention, a one-dimensional CCD is used.
A video output signal of the camera is used as an input, and a reduction filter for extracting the envelope thereof, and a video output signal of the one-dimensional CCD camera is used as a first input, and an output passed through the reduction filter is used as a second input. Respectively to the first input as compared to the second input signal.
And a two-input comparator that outputs a logically active signal when the input signal level is high.

The output of the reduction filter is used as an input,
It has an amplifier which corrects and outputs the insertion loss of the reduction filter.

[0012]

In the present invention, the reference input is the envelope of the output signal, so that the detection signal is not overlooked due to level fluctuation.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a signal waveform diagram for explaining the operation.

In FIG. 1, a video output signal S ₀ of a one-dimensional CCD camera 1 is branched in two directions, one to a reduction filter 2 (hereinafter referred to as LPF) and the other to a comparator (hereinafter referred to as CMP). 4) signal input terminal S.

The output S ₁ of the LPF ₂ is an amplifier (hereinafter referred to as A
3). The output S ₂ of AMP3 is
It is input to the reference input terminal R of CMP4.

The components shown in FIG. 1 will be described. The CCD camera 1 is a CCD type one-dimensional camera.
The LPF2 is a reduction filter whose number of time points is such that the output fluctuation caused by the difference in the illumination on the left and right of the screen passes through as it is, and the frequency components higher than that are cut off. It has a function of extracting the envelope of the signal S ₀ .

The AMP3 corrects the insertion loss of the LPF2. The CMP 4 has two input terminals, a reference input terminal R and a signal input terminal S, and outputs a positive output when the level of the S terminal is higher than that of the R terminal and a negative output when the level of the S terminal is higher. Is.

Next, the operation will be described with reference to FIGS. 1 and 2. It is assumed that the video output S ₀ of the CCD camera 1 has the waveform of S ₀ shown in FIG. 2A when viewed in cell units on the CCD chip. That is, it is assumed that dips D ₁ and D ₂ exist for the gentle envelope curve.

Here, the gentle envelope curve is caused by the nonuniformity of the illumination on the object, and the dips D ₁ and D ₂ are the signals to be detected. Thus, the signal S ₀ as the sum of the envelope curve and the dip signal is
By passing 2 the envelope curve S ₁ becomes the LP
It is output from F2.

[0020] The signals S ₁ is corrected signal S ₂ becomes the AMP3 the insertion loss LPF2, is input to the reference input terminal R of the CMP4. This signal S ₂ is shown in FIG.
It is shown in (b).

In FIG. 2, it can be seen that in S ₂ , the dips D ₁ and D ₂ are scraped off in S _{0 and} only the envelope curve is extracted.

In CMP4, S ₀ shown in FIG. 2A and S ₂ shown in FIG. 2B are compared. Only dips D ₁ and D ₂ corresponding to the difference between the signal S ₂ input to the R terminal and the signal S ₀ input to the S terminal are output as the output signal S ₃ . This signal S ₃ is shown in FIG.

This signal S ₃ is the original video signal output S _0.
Signals D with different absolute levels on the envelope curve of
_It can be seen that ₁ and D ₂ are detected without missing.

[0024]

As described above, according to the present invention, since the reference input of the binarization device is the envelope of the output signal, there is a great effect that the detection signal is hardly overlooked due to the level fluctuation.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional example.

FIG. 4 is an operation explanatory diagram in a conventional example.

[Explanation of symbols]

1 CCD camera 2 Reduction filter 3 amplifier 4 comparator

Claims (2)

[Claims] 1. A reduction filter for inputting a video output signal of a one-dimensional CCD camera and extracting an envelope thereof, and a reduction filter for receiving a video output signal of the one-dimensional CCD camera as a first input. And a two-input comparator for inputting the passed outputs to the second inputs and outputting a logically active signal when the first input signal level is higher than that of the second input signal. Binarization device. 2. The binarization apparatus according to claim 1, further comprising an amplifier which receives an output of the reduction filter and corrects and outputs an insertion loss amount of the reduction filter.