JPS5842514B2 - Eizou Shingo Hoseisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal correction device that corrects a video signal obtained by detecting a pattern using an array of photoelectric conversion elements such as a photodiode array.

Conventionally, TV cameras have been widely used to detect video signals of patterns, but recently, emphasis has been placed on the high speed and high accuracy of this detection. Diode array 1 arranged in large numbers in
Arrayed photoelectric conversion elements, including .

The method of using this is to focus an image of a pattern 5 formed on an object 4 on an arrayed photoelectric conversion element 1 through an objective lens 6 using illumination light 7 from the back side, as shown in FIG. 5 is moved in a direction perpendicular to the arrangement direction of the diode elements 2 of the arrayed photoelectric conversion element 1 as shown by an arrow 9 to detect a video signal.

That is, by electrically scanning the array photoelectric conversion element 1 with a start signal having a constant period, as shown in FIG. Video signal 8 is detected continuously.

However, since the scanning of the pattern 5 in the orthogonal direction as shown by the arrow 9 must be carried out by mechanically feeding the object 4, it is difficult to maintain the scanning speed strictly constant.

Therefore, the gap between the scanning lines that electrically scan the arrayed photoelectric conversion elements 1 cannot be kept constant on the pattern, and the arrayed photoelectric conversion elements 1 generate video signals with the shape of the pattern 5 distorted. It will be detected as 8.

Therefore, the amount of feed of the object 4 is detected by the displacement detector 10, and
The above problem can be solved by generating a start signal from the displacement detector 10 to electrically scan the arrayed photoelectric conversion elements 1 every fixed amount of feed.

However, the arrayed photoelectric conversion element 1 is generally an accumulation type, that is, it stores electricity for the time when electrical scanning is stopped, and a start signal (electrical scanning start signal) is sent at regular intervals. It has a characteristic that unless it is applied and electrically scanned and the stored amount of electricity is released, the level of the output signal will be different.

Therefore, if the feed rate of the object 4 is not constant, the time interval until a constant feed amount is obtained will be different, and the level of the video signal obtained from the arrayed photoelectric conversion element 1 will fluctuate.

The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional technology, and to increase the speed and accuracy of pattern recognition by detecting the correct image without affecting the output signal even if the table speed for feeding the object changes. An object of the present invention is to provide a video signal correction device that achieves the following.

The present invention focuses on the fact that a proportional relationship exists between the time interval of a start signal for electrically scanning an arrayed photoelectric conversion element and the level of a video signal output from the arrayed photoelectric conversion element, and Measures the time it takes for the object detected by the shaped photoelectric conversion element to displace a certain amount, and uses this measurement result as a gain to correct the level of the video signal to obtain a video signal at a constant level regardless of the object's feed speed. This is a video signal correction device characterized by the following.

The present invention will be explained below based on embodiments shown in the drawings.

First, in FIG. 1, an object 4 on which a pattern 5 whose brightness differs from that of its surroundings and which is detected by an arrayed photoelectric conversion element 1 is formed is moved by a drive device (not shown).

It moves in the direction of arrow 9 at different feed speeds.

This condition appears particularly when the object 4 starts moving.

Therefore, the displacement detector 10 for detecting the amount of movement of the object 4 generates electrical signals 11 having different time intervals as shown in FIG. 3g each time the object 4 moves a certain distance.

On the other hand, the image signal 8 of the pattern 5 is detected from the arrayed photoelectric conversion element 1 .

Next, an embodiment of a device for correcting the video signal 8 based on the electrical signal 11 will be described with reference to FIGS. 2 and 3.

12 is an inverter circuit, 13 is a multi-by-break circuit, 14 is a bootstrap circuit, and 15 is a sample-and-hold circuit.

Reference numeral 16 denotes a circuit in which a DC power source and a variable resistor are connected, and a preset voltage bV is output from the movable terminal of the variable resistor.

17 is a differential amplifier. A variable resistor 18 is provided to add a preset negative voltage to the signal output from the differential amplifier 17, and is connected between the ground and the DC power source 15.

19 is a field effect transistor (hereinafter referred to as FET).

), the gate is connected to the output of the differential amplifier 17, and the drain and source are connected to ground and the output video signal 8 of the arrayed photoelectric conversion element 1 via a resistor R1.

20 is a transistor, the base is connected to the output video signal 8 of the arrayed photoelectric conversion element 1 via a resistor R1, the emitter is connected to the ground with a resistor R2 in series, and the collector is connected with a resistor R3 in series to provide DC Connected to the positive side of power supply E.

21 is a terminal for outputting a corrected video signal, and is connected to the collector of the transistor 20.

With the above configuration, the electrical signal 11 output from the displacement detector 10 is inverted by the inverter circuit 12 and formed into the signal 22 shown in FIG.

Further, this signal is converted by the bootstrap circuit 14 into a sawtooth waveform signal 24 as shown in FIG. 3d, and is applied to the sample and hold circuit 15.

The sample and hold circuit 15 receives the signal 23 shown in FIG. 3d.
The level of the signal 24 having the sawtooth waveform is integrated and held until it is output from the one-shot multi-by-break 13, and an integrated signal 25 shown in FIG. 3e is output.

This integrated signal 25 is deviated from the reference voltage b - set by the circuit 24 in the differential amplifier 17, and the third
It is converted into the deviation signal shown in Figure f.

Furthermore, this deviation signal 12 is further added with a bias signal of about -5V set by a variable resistor 18, and the result is shown in FIG. 3g.
This voltage signal 26 is formed into a voltage signal 26 shown in FIG.
Applied to ET19.

The FET 19 uses the voltage signal 27 as a kind of proportionality constant, that is, a gain, to proportionally amplify the video signal 8.

That is, as shown in FIG. 4, within the area in which the FET is used, the drain current ID and the drain-source voltage VDS are proportional, so the voltage signal applied to the drain can be detected as the drain current ID.

The proportional constant at this time is the cutoff voltage V.

S, and the gain of the drain current ID can be changed by setting it to a negative voltage -a.

Therefore, when the deviation of the voltage signal 26 output from the differential amplifier 17 from □V is small, the FET 19 amplifies the level of the video signal 8 obtained from the arrayed photoelectric conversion element 1, and when the deviation is large, the level of the video signal 8 obtained from the arrayed photoelectric conversion element 1 is amplified. 1
The level of the video signal 8 obtained from the video signal 8 is decreased.

The video signal converted to a constant level is applied to the base of the transistor 20, and a video signal 27 at a constant level is output from the terminal 21 as shown in FIG. 3i.

As a result, it was possible to eliminate unevenness in the level of the video signal detected from the arrayed photoelectric conversion element 1, which is caused by a change in the interval of the start pulse signal due to non-uniformity in the feeding speed of the object.

As explained above, according to the present invention, the level of the video signal obtained from the arrayed photoelectric conversion elements can be kept constant even if the feeding speed of the object changes, thereby significantly improving pattern detection accuracy. be able to.

[Brief explanation of the drawing]

1a, b, and c are diagrams showing the state when pattern detection is performed using a photodiode array; FIG. 2 is a circuit diagram showing an embodiment of the video signal correction device of the present invention; and FIG.
This figure shows a signal waveform output from the circuit shown in FIG. 2, and FIG. 4 is a functional explanatory diagram of the FET shown in FIG. 2. 1... Arrayed photoelectric conversion element, 2...
Photoelectric conversion element, 4...Object, 5...Pattern, 8...Video signal, 10...Displacement detector, 14... Bootslap circuit, 15
...Sample and hold circuit, 17...
...Differential amplifier, 19...FET, 20...
...transistor.

Claims (1)

[Claims] 1. An object that forms a pattern whose brightness is different from its surroundings,
an array-like photoelectric conversion element in which a plurality of photoelectric conversion elements are arranged in a straight line for capturing an image of the object and detecting a video signal; a driving means for moving the object in a direction perpendicular to the arrangement direction; and the driving means. comprises a detection means for detecting the amount of movement of an object moved by the object, and every time the amount of movement detected by the detection means reaches a certain distance, an array of photoelectric conversion elements is electrically scanned to detect a video signal. In the device, there is provided a circuit that converts the time required for the amount of movement detected by the detection means to reach a certain distance into a signal level, and an array of photoelectric conversion elements that is inversely proportional to the signal level obtained by the circuit. Equipped with a circuit to correct the detected video signal,
A video signal correction device characterized in that a video signal of a constant level is detected from the arrayed photoelectric conversion elements.